fix bats tests

Spawns an isolated sub-shell with a minimal kubeconfig containing only the specified context.

This allows the user to launch a shell where they can only interact with a single cluster without having to worry about a command or an LLM agent interacting with other contexts.

Inside the isolated shell, most context switching/editing operations on kubectx are blocked. Nested shells not allowed.

Fixes #12.

Co-authored-by: Claude Opus 4.6 <noreply@anthropic.com>

.github/workflows/ci.yml

@@ -0,0 +1,59 @@
+# Copyright 2021 Google LLC
+#
+# Licensed under the Apache License, Version 2.0 (the "License");
+# you may not use this file except in compliance with the License.
+# You may obtain a copy of the License at
+#
+#      http://www.apache.org/licenses/LICENSE-2.0
+#
+# Unless required by applicable law or agreed to in writing, software
+# distributed under the License is distributed on an "AS IS" BASIS,
+# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+# See the License for the specific language governing permissions and
+# limitations under the License.
+
+name: Go implementation (CI)
+on:
+  push:
+  pull_request:
+jobs:
+  ci:
+    runs-on: ubuntu-latest
+    steps:
+    - name: Checkout
+      uses: actions/checkout@master
+    - name: Setup Go
+      uses: actions/setup-go@v2
+      with:
+        go-version: '1.22'
+    - id: go-cache-paths
+      run: |
+        echo "::set-output name=go-build::$(go env GOCACHE)"
+        echo "::set-output name=go-mod::$(go env GOMODCACHE)"
+    - name: Go Build Cache
+      uses: actions/cache@v4
+      with:
+        path: ${{ steps.go-cache-paths.outputs.go-build }}
+        key: ${{ runner.os }}-go-build-${{ hashFiles('**/go.sum') }}
+    - name: Go Mod Cache
+      uses: actions/cache@v4
+      with:
+        path: ${{ steps.go-cache-paths.outputs.go-mod }}
+        key: ${{ runner.os }}-go-mod-${{ hashFiles('**/go.sum') }}
+    - name: Ensure gofmt
+      run: test -z "$(gofmt -s -d .)"
+    - name: Ensure go.mod is already tidied
+      run: go mod tidy && git diff --exit-code
+    - name: Run unit tests
+      run: go test ./...
+    - name: Build with Goreleaser
+      uses: goreleaser/goreleaser-action@v2
+      with:
+        version: latest
+        args: release --snapshot --skip publish,snapcraft --clean
+    - name: Setup BATS framework
+      run: sudo npm install -g bats
+    - name: kubectx (Go) integration tests
+      run: COMMAND=./dist/kubectx_linux_amd64_v1/kubectx bats test/kubectx.bats
+    - name: kubens (Go) integration tests
+      run: COMMAND=./dist/kubens_linux_amd64_v1/kubens bats test/kubens.bats

.github/workflows/release.yml

@@ -0,0 +1,58 @@
+# Copyright 2021 Google LLC
+#
+# Licensed under the Apache License, Version 2.0 (the "License");
+# you may not use this file except in compliance with the License.
+# You may obtain a copy of the License at
+#
+#      http://www.apache.org/licenses/LICENSE-2.0
+#
+# Unless required by applicable law or agreed to in writing, software
+# distributed under the License is distributed on an "AS IS" BASIS,
+# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+# See the License for the specific language governing permissions and
+# limitations under the License.
+
+name: Release
+on:
+  push:
+    tags:
+    - 'v*.*.*'
+jobs:
+  goreleaser:
+    permissions:
+      contents: write
+    runs-on: ubuntu-latest
+    steps:
+    - name: Checkout
+      uses: actions/checkout@master
+    - run: git fetch --tags
+    - name: Setup Go
+      uses: actions/setup-go@v2
+      with:
+        go-version: '1.22'
+    - name: Install Snapcraft
+      uses: samuelmeuli/action-snapcraft@v1
+    - name: Setup Snapcraft
+      run: |
+        # https://github.com/goreleaser/goreleaser/issues/1715
+        mkdir -p $HOME/.cache/snapcraft/download
+        mkdir -p $HOME/.cache/snapcraft/stage-packages
+    - name: GoReleaser
+      uses: goreleaser/goreleaser-action@v2
+      with:
+        version: latest
+        args: release --clean
+      env:
+        GITHUB_TOKEN: ${{ secrets.GITHUB_TOKEN }}
+    - name: Update new version for plugin 'ctx' in krew-index
+      uses: rajatjindal/krew-release-bot@v0.0.38
+      with:
+        krew_template_file: .krew/ctx.yaml
+    - name: Update new version for plugin 'ns' in krew-index
+      uses: rajatjindal/krew-release-bot@v0.0.38
+      with:
+        krew_template_file: .krew/ns.yaml
+    - name: Publish Snaps to the Snap Store (stable channel)
+      run: for snap in $(ls dist/*.snap); do snapcraft upload --release=stable $snap; done
+      env:
+        SNAPCRAFT_STORE_CREDENTIALS: ${{ secrets.SNAPCRAFT_TOKEN }}

.goreleaser.yml

@@ -0,0 +1,121 @@
+# yaml-language-server: $schema=https://goreleaser.com/static/schema.json
+
+# Copyright 2021 Google LLC
+#
+# Licensed under the Apache License, Version 2.0 (the "License");
+# you may not use this file except in compliance with the License.
+# You may obtain a copy of the License at
+#
+#      http://www.apache.org/licenses/LICENSE-2.0
+#
+# Unless required by applicable law or agreed to in writing, software
+# distributed under the License is distributed on an "AS IS" BASIS,
+# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+# See the License for the specific language governing permissions and
+# limitations under the License.
+
+# This is an example goreleaser.yaml file with some sane defaults.
+# Make sure to check the documentation at http://goreleaser.com
+
+version: 2
+before:
+  hooks:
+    - go mod download
+builds:
+- id: kubectx
+  main: ./cmd/kubectx
+  binary: kubectx
+  env:
+  - CGO_ENABLED=0
+  goos:
+    - linux
+    - darwin
+    - windows
+  goarch:
+    - amd64
+    - arm
+    - arm64
+    - ppc64le
+    - s390x
+  goarm: [6, 7]
+- id: kubens
+  main: ./cmd/kubens
+  binary: kubens
+  env:
+  - CGO_ENABLED=0
+  goos:
+    - linux
+    - darwin
+    - windows
+  goarch:
+    - amd64
+    - arm
+    - arm64
+    - ppc64le
+    - s390x
+  goarm: [6, 7]
+archives:
+- id: kubectx-archive
+  name_template: |-
+    kubectx_{{ .Tag }}_{{ .Os }}_
+    {{- with .Arch -}}
+      {{- if (eq . "386") -}}i386
+      {{- else if (eq . "amd64") -}}x86_64
+      {{- else -}}{{- . -}}
+      {{- end -}} 
+    {{ end }}
+    {{- with .Arm -}}
+      {{- if (eq . "6") -}}hf
+      {{- else -}}v{{- . -}}
+      {{- end -}}
+    {{- end -}}
+  builds:
+    - kubectx
+  format_overrides:
+    - goos: windows
+      format: zip
+  files: ["LICENSE"]
+- id: kubens-archive
+  name_template: |-
+    kubens_{{ .Tag }}_{{ .Os }}_
+    {{- with .Arch -}}
+      {{- if (eq . "386") -}}i386
+      {{- else if (eq . "amd64") -}}x86_64
+      {{- else -}}{{- . -}}
+      {{- end -}}
+    {{ end }}
+    {{- with .Arm -}}
+      {{- if (eq . "6") -}}hf
+      {{- else -}}v{{- . -}}
+      {{- end -}}
+    {{- end -}}
+  builds:
+    - kubens
+  format_overrides:
+    - goos: windows
+      format: zip
+  files: ["LICENSE"]
+checksum:
+  name_template: "checksums.txt"
+  algorithm: sha256
+release:
+  extra_files:
+    - glob: ./kubens
+    - glob: ./kubectx
+snapcrafts:
+  - id: kubectx
+    name: kubectx
+    summary: 'kubectx + kubens: Power tools for kubectl'
+    description: |
+      kubectx is a tool to switch between contexts (clusters) on kubectl faster.
+      kubens is a tool to switch between Kubernetes namespaces (and configure them for kubectl) easily.
+    grade: stable
+    confinement: classic
+    base: core20
+    apps:
+      kubectx:
+        command: kubectx
+        completer: completion/kubectx.bash
+      kubens:
+        command: kubens
+        completer: completion/kubens.bash

.krew/ctx.yaml

@@ -0,0 +1,31 @@
+apiVersion: krew.googlecontainertools.github.com/v1alpha2
+kind: Plugin
+metadata:
+  name: ctx
+spec:
+  homepage: https://github.com/ahmetb/kubectx
+  shortDescription: Switch between contexts in your kubeconfig
+  version: {{ .TagName }}
+  description: |
+    Also known as "kubectx", a utility to switch between context entries in
+    your kubeconfig file efficiently.
+  caveats: |
+    If fzf is installed on your machine, you can interactively choose
+    between the entries using the arrow keys, or by fuzzy searching
+    as you type.
+    See https://github.com/ahmetb/kubectx for customization and details.
+  platforms:
+  - selector:
+      matchExpressions:
+      - key: os
+        operator: In
+        values:
+        - darwin
+        - linux
+    {{addURIAndSha "https://github.com/ahmetb/kubectx/archive/{{ .TagName }}.tar.gz" .TagName }}
+    bin: kubectx
+    files:
+    - from: kubectx-*/kubectx
+      to: .
+    - from: kubectx-*/LICENSE
+      to: .

.krew/ns.yaml

@@ -0,0 +1,30 @@
+apiVersion: krew.googlecontainertools.github.com/v1alpha2
+kind: Plugin
+metadata:
+  name: ns
+spec:
+  homepage: https://github.com/ahmetb/kubectx
+  shortDescription: Switch between Kubernetes namespaces
+  version: {{ .TagName }}
+  description: |
+    Also known as "kubens", a utility to set your current namespace and switch
+    between them.
+  caveats: |
+    If fzf is installed on your machine, you can interactively choose
+    between the entries using the arrow keys, or by fuzzy searching
+    as you type.
+  platforms:
+  - selector:
+      matchExpressions:
+      - key: os
+        operator: In
+        values:
+        - darwin
+        - linux
+    {{addURIAndSha "https://github.com/ahmetb/kubectx/archive/{{ .TagName }}.tar.gz" .TagName }}
+    bin: kubens
+    files:
+    - from: kubectx-*/kubens
+      to: .
+    - from: kubectx-*/LICENSE
+      to: .

README.md

@@ -1,98 +1,185 @@
+# `kubectx` + `kubens`: Power tools for kubectl
+
+![Latest GitHub release](https://img.shields.io/github/release/ahmetb/kubectx.svg)
+![GitHub stars](https://img.shields.io/github/stars/ahmetb/kubectx.svg?label=github%20stars)
+![Homebrew downloads](https://img.shields.io/homebrew/installs/dy/kubectx?label=macOS%20installs)
+[![Go implementation (CI)](https://github.com/ahmetb/kubectx/workflows/Go%20implementation%20(CI)/badge.svg)](https://github.com/ahmetb/kubectx/actions?query=workflow%3A"Go+implementation+(CI)")
+![Proudly written in Bash](https://img.shields.io/badge/written%20in-bash-ff69b4.svg)
+
 This repository provides both `kubectx` and `kubens` tools.
+[Install →](#installation)
 
+## What are `kubectx` and `kubens`?
 
-**`kubectx`** helps you switch between clusters back and forth:
+**kubectx** is a tool to switch between contexts (clusters) on kubectl
+faster.<br/>
+**kubens** is a tool to switch between Kubernetes namespaces (and
+configure them for kubectl) easily.
+
+Here's a **`kubectx`** demo:
 ![kubectx demo GIF](img/kubectx-demo.gif)
 
-**`kubens`** helps you switch between Kubernetes namespaces smoothly:
+...and here's a **`kubens`** demo:
 ![kubens demo GIF](img/kubens-demo.gif)
 
-# kubectx(1)
-
-kubectx is an utility to manage and switch between kubectl(1) contexts.
-
-```
-USAGE:
-  kubectx                   : list the contexts
-  kubectx <NAME>            : switch to context <NAME>
-  kubectx -                 : switch to the previous context
-  kubectx <NEW_NAME>=<NAME> : rename context <NAME> to <NEW_NAME>
-  kubectx <NEW_NAME>=.      : rename current-context to <NEW_NAME>
-  kubectx -d <NAME>         : delete context <NAME> ('.' for current-context)
-                              (this command won't delete the user/cluster entry
-                              that is used by the context)
-```
-
-### Usage
+### Examples
 
 ```sh
+# switch to another cluster that's in kubeconfig
 $ kubectx minikube
 Switched to context "minikube".
 
+# switch back to previous cluster
 $ kubectx -
 Switched to context "oregon".
 
-$ kubectx -
-Switched to context "minikube".
+# start an "isolated shell" that only has a single context
+$ kubectx -s minikube
 
+# rename context
 $ kubectx dublin=gke_ahmetb_europe-west1-b_dublin
-Context "dublin" set.
-Aliased "gke_ahmetb_europe-west1-b_dublin" as "dublin".
-```
+Context "gke_ahmetb_europe-west1-b_dublin" renamed to "dublin".
 
-`kubectx` supports <kbd>Tab</kbd> completion on bash/zsh/fish shells to help with
-long context names. You don't have to remember full context names anymore.
-
------
-
-# kubens(1)
-
-kubens is an utility to switch between Kubernetes namespaces.
-
-```
-USAGE:
-  kubens                    : list the namespaces
-  kubens <NAME>             : change the active namespace
-  kubens -                  : switch to the previous namespace
-```
-
-
-### Usage
-
-```sh
+# change the active namespace on kubectl
 $ kubens kube-system
 Context "test" set.
 Active namespace is "kube-system".
 
+# go back to the previous namespace
 $ kubens -
 Context "test" set.
 Active namespace is "default".
+
+# change the active namespace even if it doesn't exist
+$ kubens not-found-namespace --force
+Context "test" set.
+Active namespace is "not-found-namespace".
+---
+$ kubens not-found-namespace -f
+Context "test" set.
+Active namespace is "not-found-namespace".
 ```
 
-`kubens` also supports <kbd>Tab</kbd> completion on bash/zsh/fish shells.
+If you have [`fzf`](https://github.com/junegunn/fzf) installed, you can also
+**interactively** select a context or cluster, or fuzzy-search by typing a few
+characters. To learn more, read [interactive mode &rarr;](#interactive-mode)
+
+Both `kubectx` and `kubens` support <kbd>Tab</kbd> completion on bash/zsh/fish
+shells to help with long context names. You don't have to remember full context
+names anymore.
 
 -----
 
 ## Installation
 
-### macOS
+Stable versions of `kubectx` and `kubens` are small bash scripts that you
+can find in this repository.
 
-:confetti_ball: Use the [Homebrew](https://brew.sh/) package manager:
+Starting with v0.9.0, `kubectx` and `kubens` **are now rewritten in Go**.  They
+should work the same way (and we'll keep the bash-based implementations around)
+but the new features will be added to the new Go programs.  Please help us test
+this new Go implementation by downloading the binaries from the [**Releases page
+&rarr;**](https://github.com/ahmetb/kubectx/releases)
 
-    brew install kubectx
+**Installation options:**
 
-This command will set up bash/zsh/fish completion scripts automatically.
+- [as kubectl plugins (macOS & Linux)](#kubectl-plugins-macos-and-linux)
+- [with Homebrew (macOS & Linux)](#homebrew-macos-and-linux)
+- [with MacPorts (macOS)](#macports-macos)
+- [with apt (Debian)](#apt-debian)
+- [with pacman (Arch Linux)](#pacman-arch-linux)
+- [with Chocolatey (Windows)](#windows-installation-using-chocolatey)
+- [Windows Installation (using Scoop)](#windows-installation-using-scoop)
+- [with winget (Windows)](#windows-installation-using-winget)
+- [manually (macOS & Linux)](#manual-installation-macos-and-linux)
+
+If you like to add context/namespace information to your shell prompt (`$PS1`),
+you can try out [kube-ps1].
+
+[kube-ps1]: https://github.com/jonmosco/kube-ps1
+
+### Kubectl Plugins (macOS and Linux)
+
+You can install and use the [Krew](https://github.com/kubernetes-sigs/krew/) kubectl
+plugin manager to get `kubectx` and `kubens`.
+
+**Note:** This will not install the shell completion scripts. If you want them,
+*choose another installation method
+or install the scripts [manually](#manual-installation-macos-and-linux).
+
+```sh
+kubectl krew install ctx
+kubectl krew install ns
+```
+
+After installing, the tools will be available as `kubectl ctx` and `kubectl ns`.
+
+### Homebrew (macOS and Linux)
+
+If you use [Homebrew](https://brew.sh/) you can install like this:
+
+```sh
+brew install kubectx
+```
+
+This command will set up bash/zsh/fish completion scripts automatically. Make sure you [configure your shell](https://docs.brew.sh/Shell-Completion) to load completions for installed Homebrew formulas.
 
 
-- Running `brew install` with `--with-short-names` will install tools with names
-`kctx` and `kns` to prevent prefix collision with `kubectl` name.
+### MacPorts (macOS)
 
-- If you like to add context/namespace info to your shell prompt (`$PS1`),
-  I recommend trying out [kube-ps1](https://github.com/jonmosco/kube-ps1).
+If you use [MacPorts](https://www.macports.org) you can install like this:
 
-### Linux
+```sh
+sudo port install kubectx
+```
 
-Since `kubectx`/`kubens` are written in Bash, you should be able to instal
+### apt (Debian)
+
+``` bash
+sudo apt install kubectx
+```
+Newer versions might be available on repos like
+[Debian Buster (testing)](https://packages.debian.org/buster/kubectx),
+[Sid (unstable)](https://packages.debian.org/sid/kubectx)
+(_if you are unfamiliar with the Debian release process and how to enable
+testing/unstable repos, check out the
+[Debian Wiki](https://wiki.debian.org/DebianReleases)_):
+
+
+### pacman (Arch Linux)
+
+Available as official Arch Linux package. Install it via:
+
+```bash
+sudo pacman -S kubectx
+```
+
+### Windows Installation (using Chocolatey)
+
+Available as packages on [Chocolatey](https://chocolatey.org/why-chocolatey)
+```pwsh
+choco install kubens kubectx
+```
+
+### Windows Installation (using Scoop)
+
+Available as packages on [Scoop](https://scoop.sh/)
+```pwsh
+scoop bucket add main
+scoop install main/kubens main/kubectx
+```
+
+### Windows Installation (using winget)
+
+Available as packages on [winget](https://learn.microsoft.com/en-us/windows/package-manager/)
+```pwsh
+winget install --id ahmetb.kubectx
+winget install --id ahmetb.kubens
+```
+
+### Manual Installation (macOS and Linux)
+
+Since `kubectx` and `kubens` are written in Bash, you should be able to install
 them to any POSIX environment that has Bash installed.
 
 - Download the `kubectx`, and `kubens` scripts.
@@ -101,7 +188,6 @@ them to any POSIX environment that has Bash installed.
   - or save them to a directory, then create symlinks to `kubectx`/`kubens` from
     somewhere in your `PATH`, like `/usr/local/bin`
 - Make `kubectx` and `kubens` executable (`chmod +x ...`)
-- Figure out how to install bash/zsh/fish [completion scripts](completion/).
 
 Example installation steps:
 
@@ -111,56 +197,118 @@ sudo ln -s /opt/kubectx/kubectx /usr/local/bin/kubectx
 sudo ln -s /opt/kubectx/kubens /usr/local/bin/kubens
 ```
 
-#### Arch Linux
+If you also want to have shell completions, pick an installation method for the
+[completion scripts](completion/) that fits your system best: [`zsh` with
+`antibody`](#completion-scripts-for-zsh-with-antibody), [plain
+`zsh`](#completion-scripts-for-plain-zsh),
+[`bash`](#completion-scripts-for-bash) or
+[`fish`](#completion-scripts-for-fish).
 
-An unofficial [AUR package](https://aur.archlinux.org/packages/kubectx) `kubectx`
-is available. Install instructions can be found on the [Arch 
-wiki](https://wiki.archlinux.org/index.php/Arch_User_Repository#Installing_packages).
+#### Completion scripts for `zsh` with [antibody](https://getantibody.github.io)
 
-#### Debian/Ubuntu
+Add this line to your [Plugins File](https://getantibody.github.io/usage/) (e.g.
+`~/.zsh_plugins.txt`):
 
-Available as a Debian package for [Debian Buster (testing)](https://packages.debian.org/buster/kubectx), [Sid (unstable)](https://packages.debian.org/sid/kubectx) (_note: if you are unfamiliar with Debian release process and how to enable testing/unstable repos, check the [Debian Wiki](https://wiki.debian.org/DebianReleases)_):
+```
+ahmetb/kubectx path:completion kind:fpath
+```
 
-``` bash
-sudo apt install kubectx
+Depending on your setup, you might or might not need to call `compinit` or
+`autoload -U compinit && compinit` in your `~/.zshrc` after you load the Plugins
+file. If you use [oh-my-zsh](https://github.com/ohmyzsh/ohmyzsh), load the
+completions before you load `oh-my-zsh` because `oh-my-zsh` will call
+`compinit`. 
+
+#### Completion scripts for plain `zsh`
+
+The completion scripts have to be in a path that belongs to `$fpath`. Either
+link or copy them to an existing folder.
+
+Example with [`oh-my-zsh`](https://github.com/ohmyzsh/ohmyzsh):
+
+```bash
+mkdir -p ~/.oh-my-zsh/custom/completions
+chmod -R 755 ~/.oh-my-zsh/custom/completions
+ln -s /opt/kubectx/completion/_kubectx.zsh ~/.oh-my-zsh/custom/completions/_kubectx.zsh
+ln -s /opt/kubectx/completion/_kubens.zsh ~/.oh-my-zsh/custom/completions/_kubens.zsh
+echo "fpath=($ZSH/custom/completions $fpath)" >> ~/.zshrc
+```
+
+If completion doesn't work, add `autoload -U compinit && compinit` to your
+`.zshrc` (similar to
+[`zsh-completions`](https://github.com/zsh-users/zsh-completions/blob/master/README.md#oh-my-zsh)).
+
+If you are not using [`oh-my-zsh`](https://github.com/ohmyzsh/ohmyzsh), you
+could link to `/usr/share/zsh/functions/Completion` (might require sudo),
+depending on the `$fpath` of your zsh installation.
+
+In case of errors, calling `compaudit` might help.
+
+#### Completion scripts for `bash`
+
+```bash
+git clone https://github.com/ahmetb/kubectx.git ~/.kubectx
+COMPDIR=$(pkg-config --variable=completionsdir bash-completion)
+ln -sf ~/.kubectx/completion/kubens.bash $COMPDIR/kubens
+ln -sf ~/.kubectx/completion/kubectx.bash $COMPDIR/kubectx
+cat << EOF >> ~/.bashrc
+
+
+#kubectx and kubens
+export PATH=~/.kubectx:\$PATH
+EOF
+```
+
+#### Completion scripts for `fish`
+
+```fish
+mkdir -p ~/.config/fish/completions
+ln -s /opt/kubectx/completion/kubectx.fish ~/.config/fish/completions/
+ln -s /opt/kubectx/completion/kubens.fish ~/.config/fish/completions/
 ```
 
 -----
 
-### Customizing current context colors
+### Interactive mode
 
-If you like to customize the colors indicating the current namespace or context, set the environment variables `KUBECTX_CURRENT_FGCOLOR` and `KUBECTX_CURRENT_BGCOLOR` (refer color codes [here](https://linux.101hacks.com/ps1-examples/prompt-color-using-tput/)):
+If you want `kubectx` and `kubens` commands to present you an interactive menu
+with fuzzy searching, you just need to [install
+`fzf`](https://github.com/junegunn/fzf) in your `$PATH`.
 
-```
+![kubectx interactive search with fzf](img/kubectx-interactive.gif)
+
+If you have `fzf` installed, but want to opt out of using this feature, set the
+environment variable `KUBECTX_IGNORE_FZF=1`.
+
+If you want to keep `fzf` interactive mode but need the default behavior of the
+command, you can do it by piping the output to another command (e.g. `kubectx |
+cat `).
+
+-----
+
+### Customizing colors
+
+If you like to customize the colors indicating the current namespace or context,
+set the environment variables `KUBECTX_CURRENT_FGCOLOR` and
+`KUBECTX_CURRENT_BGCOLOR` (refer color codes
+[here](https://linux.101hacks.com/ps1-examples/prompt-color-using-tput/)):
+
+```sh
 export KUBECTX_CURRENT_FGCOLOR=$(tput setaf 6) # blue text
-export KUBECTX_CURRENT_BGCOLOR=$(tput setaf 7) # white background
+export KUBECTX_CURRENT_BGCOLOR=$(tput setab 7) # white background
 ```
 
-Colors in the output can be disabled by setting the 
-[`NO_COLOR`](http://no-color.org/) environment variable.
+Colors in the output can be disabled by setting the
+[`NO_COLOR`](https://no-color.org/) environment variable.
 
 -----
 
-####  Users
-
-| What are others saying about kubectx? |
-| ---- |
-| _“Thank you for kubectx & kubens - I use them all the time & have them in my k8s toolset to maintain happiness :) ”_ – [@pbouwer](https://twitter.com/pbouwer/status/925896377929949184) |
-| _“I can't imagine working without kubectx and especially kubens anymore. It's pure gold.”_ – [@timoreimann](https://twitter.com/timoreimann/status/925801946757419008) |
-| _“I'm liking kubectx from @ahmetb, makes it super-easy to switch #Kubernetes contexts [...]”_ &mdash; [@lizrice](https://twitter.com/lizrice/status/928556415517589505) |
-| _“Also using it on a daily basis. This and my zsh config that shows me the current k8s context 😉”_ – [@puja108](https://twitter.com/puja108/status/928742521139810305) |
-| _“Lately I've found myself using the kubens command more than kubectx. Both very useful though :-)”_ – [@stuartleeks](https://twitter.com/stuartleeks/status/928562850464907264) |
-| _“yeah kubens rocks!”_ – [@embano1](https://twitter.com/embano1/status/928698440732815360) |
-| _“Special thanks to Ahmet Alp Balkan for creating kubectx, kubens, and kubectl aliases, as these tools made my life better.”_ – [@strebeld](https://medium.com/@strebeld/5-ways-to-enhance-kubectl-ux-97c8893227a)
-
-> If you liked `kubectx`, you may like my [`kubectl-aliases`](https://github.com/ahmetb/kubectl-aliases) project, too.
-
------
-
-Disclaimer: This is not an official Google product.
-
+If you liked `kubectx`, you may like my
+[`kubectl-aliases`](https://github.com/ahmetb/kubectl-aliases) project, too. I
+recommend pairing kubectx and kubens with [fzf](#interactive-mode) and
+[kube-ps1].
 
 #### Stargazers over time
 
-[![Stargazers over time](https://starcharts.herokuapp.com/ahmetb/kubectx.svg)](https://starcharts.herokuapp.com/ahmetb/kubectx)
-
+[![Stargazers over time](https://starchart.cc/ahmetb/kubectx.svg)](https://starchart.cc/ahmetb/kubectx)
+![Google Analytics](https://ga-beacon.appspot.com/UA-2609286-17/kubectx/README?pixel) <!-- TODO broken since Aug 2021 as igrigorik left Google -->

cmd/kubectx/current.go

@@ -0,0 +1,45 @@
+// Copyright 2021 Google LLC
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//      http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+package main
+
+import (
+	"fmt"
+	"io"
+
+	"github.com/pkg/errors"
+
+	"github.com/ahmetb/kubectx/internal/kubeconfig"
+)
+
+// CurrentOp prints the current context
+type CurrentOp struct{}
+
+func (_op CurrentOp) Run(stdout, _ io.Writer) error {
+	if err := checkIsolatedMode(); err != nil {
+		return err
+	}
+	kc := new(kubeconfig.Kubeconfig).WithLoader(kubeconfig.DefaultLoader)
+	defer kc.Close()
+	if err := kc.Parse(); err != nil {
+		return errors.Wrap(err, "kubeconfig error")
+	}
+
+	v := kc.GetCurrentContext()
+	if v == "" {
+		return errors.New("current-context is not set")
+	}
+	_, err := fmt.Fprintln(stdout, v)
+	return errors.Wrap(err, "write error")
+}

cmd/kubectx/delete.go

@@ -0,0 +1,79 @@
+// Copyright 2021 Google LLC
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//      http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+package main
+
+import (
+	"io"
+
+	"github.com/pkg/errors"
+
+	"github.com/ahmetb/kubectx/internal/kubeconfig"
+	"github.com/ahmetb/kubectx/internal/printer"
+)
+
+// DeleteOp indicates intention to delete contexts.
+type DeleteOp struct {
+	Contexts []string // NAME or '.' to indicate current-context.
+}
+
+// deleteContexts deletes context entries one by one.
+func (op DeleteOp) Run(_, stderr io.Writer) error {
+	if err := checkIsolatedMode(); err != nil {
+		return err
+	}
+	for _, ctx := range op.Contexts {
+		// TODO inefficiency here. we open/write/close the same file many times.
+		deletedName, wasActiveContext, err := deleteContext(ctx)
+		if err != nil {
+			return errors.Wrapf(err, "error deleting context \"%s\"", deletedName)
+		}
+		if wasActiveContext {
+			printer.Warning(stderr, "You deleted the current context. Use \"%s\" to select a new context.",
+				selfName())
+		}
+
+		printer.Success(stderr, `Deleted context %s.`, printer.SuccessColor.Sprint(deletedName))
+	}
+	return nil
+}
+
+// deleteContext deletes a context entry by NAME or current-context
+// indicated by ".".
+func deleteContext(name string) (deleteName string, wasActiveContext bool, err error) {
+	kc := new(kubeconfig.Kubeconfig).WithLoader(kubeconfig.DefaultLoader)
+	defer kc.Close()
+	if err := kc.Parse(); err != nil {
+		return deleteName, false, errors.Wrap(err, "kubeconfig error")
+	}
+
+	cur := kc.GetCurrentContext()
+	// resolve "." to a real name
+	if name == "." {
+		if cur == "" {
+			return deleteName, false, errors.New("can't use '.' as the no active context is set")
+		}
+		wasActiveContext = true
+		name = cur
+	}
+
+	if !kc.ContextExists(name) {
+		return name, false, errors.New("context does not exist")
+	}
+
+	if err := kc.DeleteContextEntry(name); err != nil {
+		return name, false, errors.Wrap(err, "failed to modify yaml doc")
+	}
+	return name, wasActiveContext, errors.Wrap(kc.Save(), "failed to save modified kubeconfig file")
+}

cmd/kubectx/env.go

@@ -0,0 +1,15 @@
+// Copyright 2021 Google LLC
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//      http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+package main

cmd/kubectx/flags.go

@@ -0,0 +1,86 @@
+// Copyright 2021 Google LLC
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//      http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+package main
+
+import (
+	"fmt"
+	"io"
+	"os"
+	"strings"
+
+	"github.com/ahmetb/kubectx/internal/cmdutil"
+)
+
+// UnsupportedOp indicates an unsupported flag.
+type UnsupportedOp struct{ Err error }
+
+func (op UnsupportedOp) Run(_, _ io.Writer) error {
+	return op.Err
+}
+
+// parseArgs looks at flags (excl. executable name, i.e. argv[0])
+// and decides which operation should be taken.
+func parseArgs(argv []string) Op {
+	if len(argv) == 0 {
+		if cmdutil.IsInteractiveMode(os.Stdout) {
+			return InteractiveSwitchOp{SelfCmd: os.Args[0]}
+		}
+		return ListOp{}
+	}
+
+	if argv[0] == "--shell" || argv[0] == "-s" {
+		if len(argv) != 2 {
+			return UnsupportedOp{Err: fmt.Errorf("'%s' requires exactly one context name argument", argv[0])}
+		}
+		return ShellOp{Target: argv[1]}
+	}
+
+	if argv[0] == "-d" {
+		if len(argv) == 1 {
+			if cmdutil.IsInteractiveMode(os.Stdout) {
+				return InteractiveDeleteOp{SelfCmd: os.Args[0]}
+			} else {
+				return UnsupportedOp{Err: fmt.Errorf("'-d' needs arguments")}
+			}
+		}
+		return DeleteOp{Contexts: argv[1:]}
+	}
+
+	if len(argv) == 1 {
+		v := argv[0]
+		if v == "--help" || v == "-h" {
+			return HelpOp{}
+		}
+		if v == "--version" || v == "-V" {
+			return VersionOp{}
+		}
+		if v == "--current" || v == "-c" {
+			return CurrentOp{}
+		}
+		if v == "--unset" || v == "-u" {
+			return UnsetOp{}
+		}
+
+		if new, old, ok := parseRenameSyntax(v); ok {
+			return RenameOp{New: new, Old: old}
+		}
+
+		if strings.HasPrefix(v, "-") && v != "-" {
+			return UnsupportedOp{Err: fmt.Errorf("unsupported option '%s'", v)}
+		}
+		return SwitchOp{Target: argv[0]}
+	}
+	return UnsupportedOp{Err: fmt.Errorf("too many arguments")}
+}

cmd/kubectx/flags_test.go

@@ -0,0 +1,110 @@
+// Copyright 2021 Google LLC
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//      http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+package main
+
+import (
+	"fmt"
+	"testing"
+
+	"github.com/google/go-cmp/cmp"
+)
+
+func Test_parseArgs_new(t *testing.T) {
+	tests := []struct {
+		name string
+		args []string
+		want Op
+	}{
+		{name: "nil Args",
+			args: nil,
+			want: ListOp{}},
+		{name: "empty Args",
+			args: []string{},
+			want: ListOp{}},
+		{name: "help shorthand",
+			args: []string{"-h"},
+			want: HelpOp{}},
+		{name: "help long form",
+			args: []string{"--help"},
+			want: HelpOp{}},
+		{name: "current shorthand",
+			args: []string{"-c"},
+			want: CurrentOp{}},
+		{name: "current long form",
+			args: []string{"--current"},
+			want: CurrentOp{}},
+		{name: "unset shorthand",
+			args: []string{"-u"},
+			want: UnsetOp{}},
+		{name: "unset long form",
+			args: []string{"--unset"},
+			want: UnsetOp{}},
+		{name: "switch by name",
+			args: []string{"foo"},
+			want: SwitchOp{Target: "foo"}},
+		{name: "switch by swap",
+			args: []string{"-"},
+			want: SwitchOp{Target: "-"}},
+		{name: "delete - without contexts",
+			args: []string{"-d"},
+			want: UnsupportedOp{fmt.Errorf("'-d' needs arguments")}},
+		{name: "delete - current context",
+			args: []string{"-d", "."},
+			want: DeleteOp{[]string{"."}}},
+		{name: "delete - multiple contexts",
+			args: []string{"-d", ".", "a", "b"},
+			want: DeleteOp{[]string{".", "a", "b"}}},
+		{name: "rename context",
+			args: []string{"a=b"},
+			want: RenameOp{"a", "b"}},
+		{name: "rename context with old=current",
+			args: []string{"a=."},
+			want: RenameOp{"a", "."}},
+		{name: "shell shorthand",
+			args: []string{"-s", "prod"},
+			want: ShellOp{Target: "prod"}},
+		{name: "shell long form",
+			args: []string{"--shell", "prod"},
+			want: ShellOp{Target: "prod"}},
+		{name: "shell without context name",
+			args: []string{"-s"},
+			want: UnsupportedOp{Err: fmt.Errorf("'-s' requires exactly one context name argument")}},
+		{name: "shell with too many args",
+			args: []string{"--shell", "a", "b"},
+			want: UnsupportedOp{Err: fmt.Errorf("'--shell' requires exactly one context name argument")}},
+		{name: "unrecognized flag",
+			args: []string{"-x"},
+			want: UnsupportedOp{Err: fmt.Errorf("unsupported option '-x'")}},
+		{name: "too many args",
+			args: []string{"a", "b", "c"},
+			want: UnsupportedOp{Err: fmt.Errorf("too many arguments")}},
+	}
+	for _, tt := range tests {
+		t.Run(tt.name, func(t *testing.T) {
+			got := parseArgs(tt.args)
+
+			var opts cmp.Options
+			if _, ok := tt.want.(UnsupportedOp); ok {
+				opts = append(opts, cmp.Comparer(func(x, y UnsupportedOp) bool {
+					return (x.Err == nil && y.Err == nil) || (x.Err.Error() == y.Err.Error())
+				}))
+			}
+
+			if diff := cmp.Diff(got, tt.want, opts...); diff != "" {
+				t.Errorf("parseArgs(%#v) diff: %s", tt.args, diff)
+			}
+		})
+	}
+}

cmd/kubectx/fzf.go

@@ -0,0 +1,134 @@
+// Copyright 2021 Google LLC
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//      http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+package main
+
+import (
+	"bytes"
+	"fmt"
+	"io"
+	"os"
+	"os/exec"
+	"strings"
+
+	"github.com/pkg/errors"
+
+	"github.com/ahmetb/kubectx/internal/cmdutil"
+	"github.com/ahmetb/kubectx/internal/env"
+	"github.com/ahmetb/kubectx/internal/kubeconfig"
+	"github.com/ahmetb/kubectx/internal/printer"
+)
+
+type InteractiveSwitchOp struct {
+	SelfCmd string
+}
+
+type InteractiveDeleteOp struct {
+	SelfCmd string
+}
+
+func (op InteractiveSwitchOp) Run(_, stderr io.Writer) error {
+	if err := checkIsolatedMode(); err != nil {
+		return err
+	}
+	// parse kubeconfig just to see if it can be loaded
+	kc := new(kubeconfig.Kubeconfig).WithLoader(kubeconfig.DefaultLoader)
+	if err := kc.Parse(); err != nil {
+		if cmdutil.IsNotFoundErr(err) {
+			printer.Warning(stderr, "kubeconfig file not found")
+			return nil
+		}
+		return errors.Wrap(err, "kubeconfig error")
+	}
+	kc.Close()
+
+	cmd := exec.Command("fzf", "--ansi", "--no-preview")
+	var out bytes.Buffer
+	cmd.Stdin = os.Stdin
+	cmd.Stderr = stderr
+	cmd.Stdout = &out
+
+	cmd.Env = append(os.Environ(),
+		fmt.Sprintf("FZF_DEFAULT_COMMAND=%s", op.SelfCmd),
+		fmt.Sprintf("%s=1", env.EnvForceColor))
+	if err := cmd.Run(); err != nil {
+		if _, ok := err.(*exec.ExitError); !ok {
+			return err
+		}
+	}
+	choice := strings.TrimSpace(out.String())
+	if choice == "" {
+		return errors.New("you did not choose any of the options")
+	}
+	name, err := switchContext(choice)
+	if err != nil {
+		return errors.Wrap(err, "failed to switch context")
+	}
+	printer.Success(stderr, "Switched to context \"%s\".", printer.SuccessColor.Sprint(name))
+	return nil
+}
+
+func (op InteractiveDeleteOp) Run(_, stderr io.Writer) error {
+	if err := checkIsolatedMode(); err != nil {
+		return err
+	}
+	// parse kubeconfig just to see if it can be loaded
+	kc := new(kubeconfig.Kubeconfig).WithLoader(kubeconfig.DefaultLoader)
+	if err := kc.Parse(); err != nil {
+		if cmdutil.IsNotFoundErr(err) {
+			printer.Warning(stderr, "kubeconfig file not found")
+			return nil
+		}
+		return errors.Wrap(err, "kubeconfig error")
+	}
+	kc.Close()
+
+	if len(kc.ContextNames()) == 0 {
+		return errors.New("no contexts found in config")
+	}
+
+	cmd := exec.Command("fzf", "--ansi", "--no-preview")
+	var out bytes.Buffer
+	cmd.Stdin = os.Stdin
+	cmd.Stderr = stderr
+	cmd.Stdout = &out
+
+	cmd.Env = append(os.Environ(),
+		fmt.Sprintf("FZF_DEFAULT_COMMAND=%s", op.SelfCmd),
+		fmt.Sprintf("%s=1", env.EnvForceColor))
+	if err := cmd.Run(); err != nil {
+		if _, ok := err.(*exec.ExitError); !ok {
+			return err
+		}
+	}
+
+	choice := strings.TrimSpace(out.String())
+	if choice == "" {
+		return errors.New("you did not choose any of the options")
+	}
+
+	name, wasActiveContext, err := deleteContext(choice)
+	if err != nil {
+		return errors.Wrap(err, "failed to delete context")
+	}
+
+	if wasActiveContext {
+		printer.Warning(stderr, "You deleted the current context. Use \"%s\" to select a new context.",
+			selfName())
+	}
+
+	printer.Success(stderr, `Deleted context %s.`, printer.SuccessColor.Sprint(name))
+
+	return nil
+}

cmd/kubectx/help.go

@@ -0,0 +1,64 @@
+// Copyright 2021 Google LLC
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//      http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+package main
+
+import (
+	"fmt"
+	"io"
+	"os"
+	"path/filepath"
+	"strings"
+
+	"github.com/pkg/errors"
+)
+
+// HelpOp describes printing help.
+type HelpOp struct{}
+
+func (_ HelpOp) Run(stdout, _ io.Writer) error {
+	return printUsage(stdout)
+}
+
+func printUsage(out io.Writer) error {
+	help := `USAGE:
+  %PROG%                       : list the contexts
+  %PROG% <NAME>                : switch to context <NAME>
+  %PROG% -                     : switch to the previous context
+  %PROG% -c, --current         : show the current context name
+  %PROG% <NEW_NAME>=<NAME>     : rename context <NAME> to <NEW_NAME>
+  %PROG% <NEW_NAME>=.          : rename current-context to <NEW_NAME>
+  %PROG% -u, --unset           : unset the current context
+  %PROG% -d <NAME> [<NAME...>] : delete context <NAME> ('.' for current-context)
+  %SPAC%                         (this command won't delete the user/cluster entry
+  %SPAC%                          referenced by the context entry)
+  %PROG% -s, --shell <NAME>    : start a shell scoped to context <NAME>
+  %PROG% -h,--help             : show this message
+  %PROG% -V,--version          : show version`
+	help = strings.ReplaceAll(help, "%PROG%", selfName())
+	help = strings.ReplaceAll(help, "%SPAC%", strings.Repeat(" ", len(selfName())))
+
+	_, err := fmt.Fprintf(out, "%s\n", help)
+	return errors.Wrap(err, "write error")
+}
+
+// selfName guesses how the user invoked the program.
+func selfName() string {
+	me := filepath.Base(os.Args[0])
+	pluginPrefix := "kubectl-"
+	if strings.HasPrefix(me, pluginPrefix) {
+		return "kubectl " + strings.TrimPrefix(me, pluginPrefix)
+	}
+	return "kubectx"
+}

cmd/kubectx/help_test.go

@@ -0,0 +1,37 @@
+// Copyright 2021 Google LLC
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//      http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+package main
+
+import (
+	"bytes"
+	"strings"
+	"testing"
+)
+
+func TestPrintHelp(t *testing.T) {
+	var buf bytes.Buffer
+	if err := (&HelpOp{}).Run(&buf, &buf); err != nil {
+		t.Fatal(err)
+	}
+
+	out := buf.String()
+	if !strings.Contains(out, "USAGE:") {
+		t.Errorf("help string doesn't contain USAGE: ; output=\"%s\"", out)
+	}
+
+	if !strings.HasSuffix(out, "\n") {
+		t.Errorf("does not end with New line; output=\"%s\"", out)
+	}
+}

cmd/kubectx/isolated_shell_guard.go

@@ -0,0 +1,24 @@
+package main
+
+import (
+	"fmt"
+	"os"
+
+	"github.com/ahmetb/kubectx/internal/env"
+	"github.com/ahmetb/kubectx/internal/kubeconfig"
+)
+
+func checkIsolatedMode() error {
+	if os.Getenv(env.EnvIsolatedShell) != "1" {
+		return nil
+	}
+
+	kc := new(kubeconfig.Kubeconfig).WithLoader(kubeconfig.DefaultLoader)
+	defer kc.Close()
+	if err := kc.Parse(); err != nil {
+		return fmt.Errorf("you are in a locked single-context shell, use 'exit' to leave")
+	}
+
+	cur := kc.GetCurrentContext()
+	return fmt.Errorf("you are in a locked single-context shell (\"%s\"), use 'exit' to leave", cur)
+}

cmd/kubectx/list.go

@@ -0,0 +1,58 @@
+// Copyright 2021 Google LLC
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//      http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+package main
+
+import (
+	"fmt"
+	"io"
+
+	"facette.io/natsort"
+	"github.com/pkg/errors"
+
+	"github.com/ahmetb/kubectx/internal/cmdutil"
+	"github.com/ahmetb/kubectx/internal/kubeconfig"
+	"github.com/ahmetb/kubectx/internal/printer"
+)
+
+// ListOp describes listing contexts.
+type ListOp struct{}
+
+func (_ ListOp) Run(stdout, stderr io.Writer) error {
+	if err := checkIsolatedMode(); err != nil {
+		return err
+	}
+	kc := new(kubeconfig.Kubeconfig).WithLoader(kubeconfig.DefaultLoader)
+	defer kc.Close()
+	if err := kc.Parse(); err != nil {
+		if cmdutil.IsNotFoundErr(err) {
+			printer.Warning(stderr, "kubeconfig file not found")
+			return nil
+		}
+		return errors.Wrap(err, "kubeconfig error")
+	}
+
+	ctxs := kc.ContextNames()
+	natsort.Sort(ctxs)
+
+	cur := kc.GetCurrentContext()
+	for _, c := range ctxs {
+		s := c
+		if c == cur {
+			s = printer.ActiveItemColor.Sprint(c)
+		}
+		fmt.Fprintf(stdout, "%s\n", s)
+	}
+	return nil
+}

cmd/kubectx/main.go

@@ -0,0 +1,45 @@
+// Copyright 2021 Google LLC
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//      http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+package main
+
+import (
+	"fmt"
+	"io"
+	"os"
+
+	"github.com/ahmetb/kubectx/internal/cmdutil"
+	"github.com/ahmetb/kubectx/internal/env"
+	"github.com/ahmetb/kubectx/internal/printer"
+	"github.com/fatih/color"
+)
+
+type Op interface {
+	Run(stdout, stderr io.Writer) error
+}
+
+func main() {
+	cmdutil.PrintDeprecatedEnvWarnings(color.Error, os.Environ())
+
+	op := parseArgs(os.Args[1:])
+	if err := op.Run(color.Output, color.Error); err != nil {
+		printer.Error(color.Error, err.Error())
+
+		if _, ok := os.LookupEnv(env.EnvDebug); ok {
+			// print stack trace in verbose mode
+			fmt.Fprintf(color.Error, "[DEBUG] error: %+v\n", err)
+		}
+		defer os.Exit(1)
+	}
+}

cmd/kubectx/rename.go

@@ -0,0 +1,91 @@
+// Copyright 2021 Google LLC
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//      http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+package main
+
+import (
+	"io"
+	"strings"
+
+	"github.com/pkg/errors"
+
+	"github.com/ahmetb/kubectx/internal/kubeconfig"
+	"github.com/ahmetb/kubectx/internal/printer"
+)
+
+// RenameOp indicates intention to rename contexts.
+type RenameOp struct {
+	New string // NAME of New context
+	Old string // NAME of Old context (or '.' for current-context)
+}
+
+// parseRenameSyntax parses A=B form into [A,B] and returns
+// whether it is parsed correctly.
+func parseRenameSyntax(v string) (string, string, bool) {
+	s := strings.Split(v, "=")
+	if len(s) != 2 {
+		return "", "", false
+	}
+	new, old := s[0], s[1]
+	if new == "" || old == "" {
+		return "", "", false
+	}
+	return new, old, true
+}
+
+// rename changes the old (NAME or '.' for current-context)
+// to the "new" value. If the old refers to the current-context,
+// current-context preference is also updated.
+func (op RenameOp) Run(_, stderr io.Writer) error {
+	if err := checkIsolatedMode(); err != nil {
+		return err
+	}
+	kc := new(kubeconfig.Kubeconfig).WithLoader(kubeconfig.DefaultLoader)
+	defer kc.Close()
+	if err := kc.Parse(); err != nil {
+		return errors.Wrap(err, "kubeconfig error")
+	}
+
+	cur := kc.GetCurrentContext()
+	if op.Old == "." {
+		op.Old = cur
+	}
+
+	if !kc.ContextExists(op.Old) {
+		return errors.Errorf("context \"%s\" not found, can't rename it", op.Old)
+	}
+
+	if kc.ContextExists(op.New) {
+		printer.Warning(stderr, "context \"%s\" exists, overwriting it.", op.New)
+		if err := kc.DeleteContextEntry(op.New); err != nil {
+			return errors.Wrap(err, "failed to delete new context to overwrite it")
+		}
+	}
+
+	if err := kc.ModifyContextName(op.Old, op.New); err != nil {
+		return errors.Wrap(err, "failed to change context name")
+	}
+	if op.Old == cur {
+		if err := kc.ModifyCurrentContext(op.New); err != nil {
+			return errors.Wrap(err, "failed to set current-context to new name")
+		}
+	}
+	if err := kc.Save(); err != nil {
+		return errors.Wrap(err, "failed to save modified kubeconfig")
+	}
+	printer.Success(stderr, "Context %s renamed to %s.",
+		printer.SuccessColor.Sprint(op.Old),
+		printer.SuccessColor.Sprint(op.New))
+	return nil
+}

cmd/kubectx/rename_test.go

@@ -0,0 +1,83 @@
+// Copyright 2021 Google LLC
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//      http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+package main
+
+import (
+	"testing"
+
+	"github.com/google/go-cmp/cmp"
+)
+
+func Test_parseRenameSyntax(t *testing.T) {
+
+	type out struct {
+		New string
+		Old string
+		OK  bool
+	}
+	tests := []struct {
+		name string
+		in   string
+		want out
+	}{
+		{
+			name: "no equals sign",
+			in:   "foo",
+			want: out{OK: false},
+		},
+		{
+			name: "no left side",
+			in:   "=a",
+			want: out{OK: false},
+		},
+		{
+			name: "no right side",
+			in:   "a=",
+			want: out{OK: false},
+		},
+		{
+			name: "correct format",
+			in:   "a=b",
+			want: out{
+				New: "a",
+				Old: "b",
+				OK:  true,
+			},
+		},
+		{
+			name: "correct format with current context",
+			in:   "NEW_NAME=.",
+			want: out{
+				New: "NEW_NAME",
+				Old: ".",
+				OK:  true,
+			},
+		},
+	}
+	for _, tt := range tests {
+		t.Run(tt.name, func(t *testing.T) {
+			new, old, ok := parseRenameSyntax(tt.in)
+			got := out{
+				New: new,
+				Old: old,
+				OK:  ok,
+			}
+			diff := cmp.Diff(tt.want, got)
+			if diff != "" {
+				t.Errorf("parseRenameSyntax() diff=%s", diff)
+			}
+		})
+	}
+}

cmd/kubectx/shell.go

@@ -0,0 +1,135 @@
+package main
+
+import (
+	"fmt"
+	"io"
+	"os"
+	"os/exec"
+	"runtime"
+
+	"github.com/fatih/color"
+	"github.com/pkg/errors"
+
+	"github.com/ahmetb/kubectx/internal/env"
+	"github.com/ahmetb/kubectx/internal/kubeconfig"
+	"github.com/ahmetb/kubectx/internal/printer"
+)
+
+// ShellOp indicates intention to start a scoped sub-shell for a context.
+type ShellOp struct {
+	Target string
+}
+
+func (op ShellOp) Run(_, stderr io.Writer) error {
+	if err := checkIsolatedMode(); err != nil {
+		return err
+	}
+
+	kubectlPath, err := resolveKubectl()
+	if err != nil {
+		return err
+	}
+
+	// Verify context exists and get current context for exit message
+	kc := new(kubeconfig.Kubeconfig).WithLoader(kubeconfig.DefaultLoader)
+	defer kc.Close()
+	if err := kc.Parse(); err != nil {
+		return errors.Wrap(err, "kubeconfig error")
+	}
+	if !kc.ContextExists(op.Target) {
+		return fmt.Errorf("no context exists with the name: \"%s\"", op.Target)
+	}
+	previousCtx := kc.GetCurrentContext()
+
+	// Extract minimal kubeconfig using kubectl
+	data, err := extractMinimalKubeconfig(kubectlPath, op.Target)
+	if err != nil {
+		return errors.Wrap(err, "failed to extract kubeconfig for context")
+	}
+
+	// Write to temp file
+	tmpFile, err := os.CreateTemp("", "kubectx-shell-*.yaml")
+	if err != nil {
+		return errors.Wrap(err, "failed to create temp kubeconfig file")
+	}
+	tmpPath := tmpFile.Name()
+	defer os.Remove(tmpPath)
+
+	if _, err := tmpFile.Write(data); err != nil {
+		tmpFile.Close()
+		return errors.Wrap(err, "failed to write temp kubeconfig")
+	}
+	tmpFile.Close()
+
+	// Print entry message
+	badgeColor := color.New(color.BgRed, color.FgWhite, color.Bold)
+	printer.EnableOrDisableColor(badgeColor)
+	fmt.Fprintf(stderr, "%s kubectl context is %s in this shell — type 'exit' to leave.\n",
+		badgeColor.Sprint("[ISOLATED SHELL]"), printer.WarningColor.Sprint(op.Target))
+
+	// Detect and start shell
+	shellBin := detectShell()
+	cmd := exec.Command(shellBin)
+	cmd.Stdin = os.Stdin
+	cmd.Stdout = os.Stdout
+	cmd.Stderr = os.Stderr
+	cmd.Env = append(os.Environ(),
+		"KUBECONFIG="+tmpPath,
+		env.EnvIsolatedShell+"=1",
+	)
+
+	_ = cmd.Run()
+
+	// Print exit message
+	fmt.Fprintf(stderr, "%s kubectl context is now %s.\n",
+		badgeColor.Sprint("[ISOLATED SHELL EXITED]"), printer.WarningColor.Sprint(previousCtx))
+
+	return nil
+}
+
+func resolveKubectl() (string, error) {
+	if v := os.Getenv("KUBECTL"); v != "" {
+		return v, nil
+	}
+	path, err := exec.LookPath("kubectl")
+	if err != nil {
+		return "", fmt.Errorf("kubectl is required for --shell but was not found in PATH")
+	}
+	return path, nil
+}
+
+func extractMinimalKubeconfig(kubectlPath, contextName string) ([]byte, error) {
+	cmd := exec.Command(kubectlPath, "config", "view", "--minify", "--flatten",
+		"--context", contextName)
+	cmd.Env = os.Environ()
+	data, err := cmd.Output()
+	if err != nil {
+		return nil, fmt.Errorf("kubectl config view failed: %w", err)
+	}
+	return data, nil
+}
+
+func detectShell() string {
+	if runtime.GOOS == "windows" {
+		// cmd.exe always sets the PROMPT env var, so if it is present
+		// we can reliably assume we are running inside cmd.exe.
+		if os.Getenv("PROMPT") != "" {
+			return "cmd.exe"
+		}
+		// Otherwise assume PowerShell. PSModulePath is always set on
+		// Windows regardless of the shell, so it cannot be used as a
+		// discriminator; however the absence of PROMPT is a strong
+		// enough signal that we are in a PowerShell session.
+		if pwsh, err := exec.LookPath("pwsh"); err == nil {
+			return pwsh
+		}
+		if powershell, err := exec.LookPath("powershell"); err == nil {
+			return powershell
+		}
+		return "cmd.exe"
+	}
+	if v := os.Getenv("SHELL"); v != "" {
+		return v
+	}
+	return "/bin/sh"
+}

cmd/kubectx/shell_test.go

@@ -0,0 +1,131 @@
+package main
+
+import (
+	"bytes"
+	"os"
+	"runtime"
+	"testing"
+
+	"github.com/ahmetb/kubectx/internal/env"
+)
+
+func Test_detectShell_unix(t *testing.T) {
+	if runtime.GOOS == "windows" {
+		t.Skip("skipping unix shell detection test on windows")
+	}
+
+	tests := []struct {
+		name     string
+		shellEnv string
+		want     string
+	}{
+		{
+			name:     "SHELL env set",
+			shellEnv: "/bin/zsh",
+			want:     "/bin/zsh",
+		},
+		{
+			name:     "SHELL env empty, falls back to /bin/sh",
+			shellEnv: "",
+			want:     "/bin/sh",
+		},
+	}
+
+	for _, tt := range tests {
+		t.Run(tt.name, func(t *testing.T) {
+			orig := os.Getenv("SHELL")
+			defer os.Setenv("SHELL", orig)
+
+			os.Setenv("SHELL", tt.shellEnv)
+			if tt.shellEnv == "" {
+				os.Unsetenv("SHELL")
+			}
+
+			got := detectShell()
+			if got != tt.want {
+				t.Errorf("detectShell() = %q, want %q", got, tt.want)
+			}
+		})
+	}
+}
+
+func Test_ShellOp_blockedWhenNested(t *testing.T) {
+	// Simulate being inside an isolated shell
+	orig := os.Getenv(env.EnvIsolatedShell)
+	defer os.Setenv(env.EnvIsolatedShell, orig)
+	os.Setenv(env.EnvIsolatedShell, "1")
+
+	op := ShellOp{Target: "some-context"}
+	var stdout, stderr bytes.Buffer
+	err := op.Run(&stdout, &stderr)
+
+	if err == nil {
+		t.Fatal("expected error when running ShellOp inside isolated shell, got nil")
+	}
+
+	want := "locked single-context shell to"
+	if !bytes.Contains([]byte(err.Error()), []byte(want)) {
+		// The error may not contain the context name if kubeconfig is not available,
+		// but it should still be blocked
+		want2 := "locked single-context shell"
+		if !bytes.Contains([]byte(err.Error()), []byte(want2)) {
+			t.Errorf("error message %q does not contain %q", err.Error(), want2)
+		}
+	}
+}
+
+func Test_resolveKubectl_envVar(t *testing.T) {
+	orig := os.Getenv("KUBECTL")
+	defer os.Setenv("KUBECTL", orig)
+
+	os.Setenv("KUBECTL", "/custom/path/kubectl")
+	got, err := resolveKubectl()
+	if err != nil {
+		t.Fatalf("unexpected error: %v", err)
+	}
+	if got != "/custom/path/kubectl" {
+		t.Errorf("resolveKubectl() = %q, want %q", got, "/custom/path/kubectl")
+	}
+}
+
+func Test_resolveKubectl_inPath(t *testing.T) {
+	orig := os.Getenv("KUBECTL")
+	defer os.Setenv("KUBECTL", orig)
+	os.Unsetenv("KUBECTL")
+
+	// kubectl should be findable in PATH on most dev machines
+	got, err := resolveKubectl()
+	if err != nil {
+		t.Skip("kubectl not in PATH, skipping")
+	}
+	if got == "" {
+		t.Error("resolveKubectl() returned empty string")
+	}
+}
+
+func Test_checkIsolatedMode_notSet(t *testing.T) {
+	orig := os.Getenv(env.EnvIsolatedShell)
+	defer os.Setenv(env.EnvIsolatedShell, orig)
+	os.Unsetenv(env.EnvIsolatedShell)
+
+	err := checkIsolatedMode()
+	if err != nil {
+		t.Errorf("expected nil error when not in isolated mode, got: %v", err)
+	}
+}
+
+func Test_checkIsolatedMode_set(t *testing.T) {
+	orig := os.Getenv(env.EnvIsolatedShell)
+	defer os.Setenv(env.EnvIsolatedShell, orig)
+	os.Setenv(env.EnvIsolatedShell, "1")
+
+	err := checkIsolatedMode()
+	if err == nil {
+		t.Fatal("expected error when in isolated mode, got nil")
+	}
+
+	want := "locked single-context shell"
+	if !bytes.Contains([]byte(err.Error()), []byte(want)) {
+		t.Errorf("error message %q does not contain %q", err.Error(), want)
+	}
+}

cmd/kubectx/state.go

@@ -0,0 +1,53 @@
+// Copyright 2021 Google LLC
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//      http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+package main
+
+import (
+	"io/ioutil"
+	"os"
+	"path/filepath"
+
+	"github.com/pkg/errors"
+
+	"github.com/ahmetb/kubectx/internal/cmdutil"
+)
+
+func kubectxPrevCtxFile() (string, error) {
+	home := cmdutil.HomeDir()
+	if home == "" {
+		return "", errors.New("HOME or USERPROFILE environment variable not set")
+	}
+	return filepath.Join(home, ".kube", "kubectx"), nil
+}
+
+// readLastContext returns the saved previous context
+// if the state file exists, otherwise returns "".
+func readLastContext(path string) (string, error) {
+	b, err := ioutil.ReadFile(path)
+	if os.IsNotExist(err) {
+		return "", nil
+	}
+	return string(b), err
+}
+
+// writeLastContext saves the specified value to the state file.
+// It creates missing parent directories.
+func writeLastContext(path, value string) error {
+	dir := filepath.Dir(path)
+	if err := os.MkdirAll(dir, 0755); err != nil {
+		return errors.Wrap(err, "failed to create parent directories")
+	}
+	return ioutil.WriteFile(path, []byte(value), 0644)
+}

cmd/kubectx/state_test.go

@@ -0,0 +1,104 @@
+// Copyright 2021 Google LLC
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//      http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+package main
+
+import (
+	"io/ioutil"
+	"os"
+	"path/filepath"
+	"testing"
+
+	"github.com/ahmetb/kubectx/internal/testutil"
+)
+
+func Test_readLastContext_nonExistingFile(t *testing.T) {
+	s, err := readLastContext(filepath.FromSlash("/non/existing/file"))
+	if err != nil {
+		t.Fatal(err)
+	}
+	if s != "" {
+		t.Fatalf("expected empty string; got=\"%s\"", s)
+	}
+}
+
+func Test_readLastContext(t *testing.T) {
+	path, cleanup := testutil.TempFile(t, "foo")
+	defer cleanup()
+
+	s, err := readLastContext(path)
+	if err != nil {
+		t.Fatal(err)
+	}
+	if expected := "foo"; s != expected {
+		t.Fatalf("expected=\"%s\"; got=\"%s\"", expected, s)
+	}
+}
+
+func Test_writeLastContext_err(t *testing.T) {
+	path := filepath.Join(os.DevNull, "foo", "bar")
+	err := writeLastContext(path, "foo")
+	if err == nil {
+		t.Fatal("got empty error")
+	}
+}
+
+func Test_writeLastContext(t *testing.T) {
+	dir, err := ioutil.TempDir(os.TempDir(), "state-file-test")
+	if err != nil {
+		t.Fatal(err)
+	}
+	path := filepath.Join(dir, "foo", "bar")
+
+	if err := writeLastContext(path, "ctx1"); err != nil {
+		t.Fatal(err)
+	}
+
+	v, err := readLastContext(path)
+	if err != nil {
+		t.Fatal(err)
+	}
+	if expected := "ctx1"; v != expected {
+		t.Fatalf("read wrong value=\"%s\"; expected=\"%s\"", v, expected)
+	}
+}
+
+func Test_kubectxFilePath(t *testing.T) {
+	origHome := os.Getenv("HOME")
+	os.Setenv("HOME", filepath.FromSlash("/foo/bar"))
+	defer os.Setenv("HOME", origHome)
+
+	expected := filepath.Join(filepath.FromSlash("/foo/bar"), ".kube", "kubectx")
+	v, err := kubectxPrevCtxFile()
+	if err != nil {
+		t.Fatal(err)
+	}
+	if v != expected {
+		t.Fatalf("expected=\"%s\" got=\"%s\"", expected, v)
+	}
+}
+
+func Test_kubectxFilePath_error(t *testing.T) {
+	origHome := os.Getenv("HOME")
+	origUserprofile := os.Getenv("USERPROFILE")
+	os.Unsetenv("HOME")
+	os.Unsetenv("USERPROFILE")
+	defer os.Setenv("HOME", origHome)
+	defer os.Setenv("USERPROFILE", origUserprofile)
+
+	_, err := kubectxPrevCtxFile()
+	if err == nil {
+		t.Fatal(err)
+	}
+}

cmd/kubectx/switch.go

@@ -0,0 +1,95 @@
+// Copyright 2021 Google LLC
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//      http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+package main
+
+import (
+	"io"
+
+	"github.com/pkg/errors"
+
+	"github.com/ahmetb/kubectx/internal/kubeconfig"
+	"github.com/ahmetb/kubectx/internal/printer"
+)
+
+// SwitchOp indicates intention to switch contexts.
+type SwitchOp struct {
+	Target string // '-' for back and forth, or NAME
+}
+
+func (op SwitchOp) Run(_, stderr io.Writer) error {
+	if err := checkIsolatedMode(); err != nil {
+		return err
+	}
+	var newCtx string
+	var err error
+	if op.Target == "-" {
+		newCtx, err = swapContext()
+	} else {
+		newCtx, err = switchContext(op.Target)
+	}
+	if err != nil {
+		return errors.Wrap(err, "failed to switch context")
+	}
+	err = printer.Success(stderr, "Switched to context \"%s\".", printer.SuccessColor.Sprint(newCtx))
+	return errors.Wrap(err, "print error")
+}
+
+// switchContext switches to specified context name.
+func switchContext(name string) (string, error) {
+	prevCtxFile, err := kubectxPrevCtxFile()
+	if err != nil {
+		return "", errors.Wrap(err, "failed to determine state file")
+	}
+
+	kc := new(kubeconfig.Kubeconfig).WithLoader(kubeconfig.DefaultLoader)
+	defer kc.Close()
+	if err := kc.Parse(); err != nil {
+		return "", errors.Wrap(err, "kubeconfig error")
+	}
+
+	prev := kc.GetCurrentContext()
+	if !kc.ContextExists(name) {
+		return "", errors.Errorf("no context exists with the name: \"%s\"", name)
+	}
+	if err := kc.ModifyCurrentContext(name); err != nil {
+		return "", err
+	}
+	if err := kc.Save(); err != nil {
+		return "", errors.Wrap(err, "failed to save kubeconfig")
+	}
+
+	if prev != name {
+		if err := writeLastContext(prevCtxFile, prev); err != nil {
+			return "", errors.Wrap(err, "failed to save previous context name")
+		}
+	}
+	return name, nil
+}
+
+// swapContext switches to previously switch context.
+func swapContext() (string, error) {
+	prevCtxFile, err := kubectxPrevCtxFile()
+	if err != nil {
+		return "", errors.Wrap(err, "failed to determine state file")
+	}
+	prev, err := readLastContext(prevCtxFile)
+	if err != nil {
+		return "", errors.Wrap(err, "failed to read previous context file")
+	}
+	if prev == "" {
+		return "", errors.New("no previous context found")
+	}
+	return switchContext(prev)
+}

cmd/kubectx/unset.go

@@ -0,0 +1,48 @@
+// Copyright 2021 Google LLC
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//      http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+package main
+
+import (
+	"io"
+
+	"github.com/pkg/errors"
+
+	"github.com/ahmetb/kubectx/internal/kubeconfig"
+	"github.com/ahmetb/kubectx/internal/printer"
+)
+
+// UnsetOp indicates intention to remove current-context preference.
+type UnsetOp struct{}
+
+func (_ UnsetOp) Run(_, stderr io.Writer) error {
+	if err := checkIsolatedMode(); err != nil {
+		return err
+	}
+	kc := new(kubeconfig.Kubeconfig).WithLoader(kubeconfig.DefaultLoader)
+	defer kc.Close()
+	if err := kc.Parse(); err != nil {
+		return errors.Wrap(err, "kubeconfig error")
+	}
+
+	if err := kc.UnsetCurrentContext(); err != nil {
+		return errors.Wrap(err, "error while modifying current-context")
+	}
+	if err := kc.Save(); err != nil {
+		return errors.Wrap(err, "failed to save kubeconfig file after modification")
+	}
+
+	err := printer.Success(stderr, "Active context unset for kubectl.")
+	return errors.Wrap(err, "write error")
+}

cmd/kubectx/version.go

@@ -0,0 +1,20 @@
+package main
+
+import (
+	"fmt"
+	"io"
+
+	"github.com/pkg/errors"
+)
+
+var (
+	version = "v0.0.0+unknown" // populated by goreleaser
+)
+
+// VersionOp describes printing version string.
+type VersionOp struct{}
+
+func (_ VersionOp) Run(stdout, _ io.Writer) error {
+	_, err := fmt.Fprintf(stdout, "%s\n", version)
+	return errors.Wrap(err, "write error")
+}

cmd/kubens/current.go

@@ -0,0 +1,45 @@
+// Copyright 2021 Google LLC
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//      http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+package main
+
+import (
+	"fmt"
+	"io"
+
+	"github.com/pkg/errors"
+
+	"github.com/ahmetb/kubectx/internal/kubeconfig"
+)
+
+type CurrentOp struct{}
+
+func (c CurrentOp) Run(stdout, _ io.Writer) error {
+	kc := new(kubeconfig.Kubeconfig).WithLoader(kubeconfig.DefaultLoader)
+	defer kc.Close()
+	if err := kc.Parse(); err != nil {
+		return errors.Wrap(err, "kubeconfig error")
+	}
+
+	ctx := kc.GetCurrentContext()
+	if ctx == "" {
+		return errors.New("current-context is not set")
+	}
+	ns, err := kc.NamespaceOfContext(ctx)
+	if err != nil {
+		return errors.Wrapf(err, "failed to read namespace of \"%s\"", ctx)
+	}
+	_, err = fmt.Fprintln(stdout, ns)
+	return errors.Wrap(err, "write error")
+}

cmd/kubens/flags.go

@@ -0,0 +1,84 @@
+// Copyright 2021 Google LLC
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//      http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+package main
+
+import (
+	"fmt"
+	"io"
+	"os"
+	"slices"
+	"strings"
+
+	"github.com/ahmetb/kubectx/internal/cmdutil"
+)
+
+// UnsupportedOp indicates an unsupported flag.
+type UnsupportedOp struct{ Err error }
+
+func (op UnsupportedOp) Run(_, _ io.Writer) error {
+	return op.Err
+}
+
+// parseArgs looks at flags (excl. executable name, i.e. argv[0])
+// and decides which operation should be taken.
+func parseArgs(argv []string) Op {
+	n := len(argv)
+
+	if n == 0 {
+		if cmdutil.IsInteractiveMode(os.Stdout) {
+			return InteractiveSwitchOp{SelfCmd: os.Args[0]}
+		}
+		return ListOp{}
+	}
+
+	if n == 1 {
+		v := argv[0]
+		switch v {
+		case "--help", "-h":
+			return HelpOp{}
+		case "--version", "-V":
+			return VersionOp{}
+		case "--current", "-c":
+			return CurrentOp{}
+		default:
+			return getSwitchOp(v, false)
+		}
+	} else if n == 2 {
+		// {namespace} -f|--force
+		name := argv[0]
+		force := slices.Contains([]string{"-f", "--force"}, argv[1])
+
+		if !force {
+			if !slices.Contains([]string{"-f", "--force"}, argv[0]) {
+				return UnsupportedOp{Err: fmt.Errorf("unsupported arguments %q", argv)}
+			}
+
+			// -f|--force {namespace}
+			force = true
+			name = argv[1]
+		}
+
+		return getSwitchOp(name, force)
+	}
+
+	return UnsupportedOp{Err: fmt.Errorf("too many arguments")}
+}
+
+func getSwitchOp(v string, force bool) Op {
+	if strings.HasPrefix(v, "-") && v != "-" {
+		return UnsupportedOp{Err: fmt.Errorf("unsupported option %q", v)}
+	}
+	return SwitchOp{Target: v, Force: force}
+}

cmd/kubens/flags_test.go

@@ -0,0 +1,95 @@
+// Copyright 2021 Google LLC
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//      http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+package main
+
+import (
+	"fmt"
+	"testing"
+
+	"github.com/google/go-cmp/cmp"
+)
+
+func Test_parseArgs_new(t *testing.T) {
+	tests := []struct {
+		name string
+		args []string
+		want Op
+	}{
+		{name: "nil Args",
+			args: nil,
+			want: ListOp{}},
+		{name: "empty Args",
+			args: []string{},
+			want: ListOp{}},
+		{name: "help shorthand",
+			args: []string{"-h"},
+			want: HelpOp{}},
+		{name: "help long form",
+			args: []string{"--help"},
+			want: HelpOp{}},
+		{name: "current shorthand",
+			args: []string{"-c"},
+			want: CurrentOp{}},
+		{name: "current long form",
+			args: []string{"--current"},
+			want: CurrentOp{}},
+		{name: "switch by name",
+			args: []string{"foo"},
+			want: SwitchOp{Target: "foo"}},
+		{name: "switch by name force short flag",
+			args: []string{"foo", "-f"},
+			want: SwitchOp{Target: "foo", Force: true}},
+		{name: "switch by name force long flag",
+			args: []string{"foo", "--force"},
+			want: SwitchOp{Target: "foo", Force: true}},
+		{name: "switch by name force short flag before name",
+			args: []string{"-f", "foo"},
+			want: SwitchOp{Target: "foo", Force: true}},
+		{name: "switch by name force long flag before name",
+			args: []string{"--force", "foo"},
+			want: SwitchOp{Target: "foo", Force: true}},
+		{name: "switch by name unknown arguments",
+			args: []string{"foo", "-x"},
+			want: UnsupportedOp{Err: fmt.Errorf("unsupported arguments %q", []string{"foo", "-x"})}},
+		{name: "switch by name unknown arguments",
+			args: []string{"-x", "foo"},
+			want: UnsupportedOp{Err: fmt.Errorf("unsupported arguments %q", []string{"-x", "foo"})}},
+		{name: "switch by swap",
+			args: []string{"-"},
+			want: SwitchOp{Target: "-"}},
+		{name: "unrecognized flag",
+			args: []string{"-x"},
+			want: UnsupportedOp{Err: fmt.Errorf("unsupported option %q", "-x")}},
+		{name: "too many args",
+			args: []string{"a", "b", "c"},
+			want: UnsupportedOp{Err: fmt.Errorf("too many arguments")}},
+	}
+	for _, tt := range tests {
+		t.Run(tt.name, func(t *testing.T) {
+			got := parseArgs(tt.args)
+
+			var opts cmp.Options
+			if _, ok := tt.want.(UnsupportedOp); ok {
+				opts = append(opts, cmp.Comparer(func(x, y UnsupportedOp) bool {
+					return (x.Err == nil && y.Err == nil) || (x.Err.Error() == y.Err.Error())
+				}))
+			}
+
+			if diff := cmp.Diff(got, tt.want, opts...); diff != "" {
+				t.Errorf("parseArgs(%#v) diff: %s", tt.args, diff)
+			}
+		})
+	}
+}

cmd/kubens/fzf.go

@@ -0,0 +1,74 @@
+// Copyright 2021 Google LLC
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//      http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+package main
+
+import (
+	"bytes"
+	"fmt"
+	"io"
+	"os"
+	"os/exec"
+	"strings"
+
+	"github.com/pkg/errors"
+
+	"github.com/ahmetb/kubectx/internal/cmdutil"
+	"github.com/ahmetb/kubectx/internal/env"
+	"github.com/ahmetb/kubectx/internal/kubeconfig"
+	"github.com/ahmetb/kubectx/internal/printer"
+)
+
+type InteractiveSwitchOp struct {
+	SelfCmd string
+}
+
+// TODO(ahmetb) This method is heavily repetitive vs kubectx/fzf.go.
+func (op InteractiveSwitchOp) Run(_, stderr io.Writer) error {
+	// parse kubeconfig just to see if it can be loaded
+	kc := new(kubeconfig.Kubeconfig).WithLoader(kubeconfig.DefaultLoader)
+	if err := kc.Parse(); err != nil {
+		if cmdutil.IsNotFoundErr(err) {
+			printer.Warning(stderr, "kubeconfig file not found")
+			return nil
+		}
+		return errors.Wrap(err, "kubeconfig error")
+	}
+	defer kc.Close()
+
+	cmd := exec.Command("fzf", "--ansi", "--no-preview")
+	var out bytes.Buffer
+	cmd.Stdin = os.Stdin
+	cmd.Stderr = stderr
+	cmd.Stdout = &out
+
+	cmd.Env = append(os.Environ(),
+		fmt.Sprintf("FZF_DEFAULT_COMMAND=%s", op.SelfCmd),
+		fmt.Sprintf("%s=1", env.EnvForceColor))
+	if err := cmd.Run(); err != nil {
+		if _, ok := err.(*exec.ExitError); !ok {
+			return err
+		}
+	}
+	choice := strings.TrimSpace(out.String())
+	if choice == "" {
+		return errors.New("you did not choose any of the options")
+	}
+	name, err := switchNamespace(kc, choice, false)
+	if err != nil {
+		return errors.Wrap(err, "failed to switch namespace")
+	}
+	printer.Success(stderr, "Active namespace is \"%s\".", printer.SuccessColor.Sprint(name))
+	return nil
+}

cmd/kubens/help.go

@@ -0,0 +1,60 @@
+// Copyright 2021 Google LLC
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//      http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+package main
+
+import (
+	"fmt"
+	"io"
+	"os"
+	"path/filepath"
+	"strings"
+
+	"github.com/pkg/errors"
+)
+
+// HelpOp describes printing help.
+type HelpOp struct{}
+
+func (_ HelpOp) Run(stdout, _ io.Writer) error {
+	return printUsage(stdout)
+}
+
+func printUsage(out io.Writer) error {
+	help := `USAGE:
+  %PROG%                    : list the namespaces in the current context
+  %PROG% <NAME>             : change the active namespace of current context
+  %PROG% <NAME> --force/-f  : force change the active namespace of current context (even if it doesn't exist)
+  %PROG% -                  : switch to the previous namespace in this context
+  %PROG% -c, --current      : show the current namespace
+  %PROG% -h,--help          : show this message
+  %PROG% -V,--version       : show version`
+
+	// TODO this replace logic is duplicated between this and kubectx
+	help = strings.ReplaceAll(help, "%PROG%", selfName())
+
+	_, err := fmt.Fprintf(out, "%s\n", help)
+	return errors.Wrap(err, "write error")
+}
+
+// selfName guesses how the user invoked the program.
+func selfName() string {
+	// TODO this method is duplicated between this and kubectx
+	me := filepath.Base(os.Args[0])
+	pluginPrefix := "kubectl-"
+	if strings.HasPrefix(me, pluginPrefix) {
+		return "kubectl " + strings.TrimPrefix(me, pluginPrefix)
+	}
+	return "kubens"
+}

cmd/kubens/list.go

@@ -0,0 +1,109 @@
+// Copyright 2021 Google LLC
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//      http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+package main
+
+import (
+	"context"
+	"fmt"
+	"io"
+	"os"
+
+	"github.com/pkg/errors"
+	metav1 "k8s.io/apimachinery/pkg/apis/meta/v1"
+	"k8s.io/client-go/kubernetes"
+	_ "k8s.io/client-go/plugin/pkg/client/auth"
+	"k8s.io/client-go/tools/clientcmd"
+
+	"github.com/ahmetb/kubectx/internal/kubeconfig"
+	"github.com/ahmetb/kubectx/internal/printer"
+)
+
+type ListOp struct{}
+
+func (op ListOp) Run(stdout, stderr io.Writer) error {
+	kc := new(kubeconfig.Kubeconfig).WithLoader(kubeconfig.DefaultLoader)
+	defer kc.Close()
+	if err := kc.Parse(); err != nil {
+		return errors.Wrap(err, "kubeconfig error")
+	}
+
+	ctx := kc.GetCurrentContext()
+	if ctx == "" {
+		return errors.New("current-context is not set")
+	}
+	curNs, err := kc.NamespaceOfContext(ctx)
+	if err != nil {
+		return errors.Wrap(err, "cannot read current namespace")
+	}
+
+	ns, err := queryNamespaces(kc)
+	if err != nil {
+		return errors.Wrap(err, "could not list namespaces (is the cluster accessible?)")
+	}
+
+	for _, c := range ns {
+		s := c
+		if c == curNs {
+			s = printer.ActiveItemColor.Sprint(c)
+		}
+		fmt.Fprintf(stdout, "%s\n", s)
+	}
+	return nil
+}
+
+func queryNamespaces(kc *kubeconfig.Kubeconfig) ([]string, error) {
+	if os.Getenv("_MOCK_NAMESPACES") != "" {
+		return []string{"ns1", "ns2"}, nil
+	}
+
+	clientset, err := newKubernetesClientSet(kc)
+	if err != nil {
+		return nil, errors.Wrap(err, "failed to initialize k8s REST client")
+	}
+
+	var out []string
+	var next string
+	for {
+		list, err := clientset.CoreV1().Namespaces().List(
+			context.Background(),
+			metav1.ListOptions{
+				Limit:    500,
+				Continue: next,
+			})
+		if err != nil {
+			return nil, errors.Wrap(err, "failed to list namespaces from k8s API")
+		}
+		next = list.Continue
+		for _, it := range list.Items {
+			out = append(out, it.Name)
+		}
+		if next == "" {
+			break
+		}
+	}
+	return out, nil
+}
+
+func newKubernetesClientSet(kc *kubeconfig.Kubeconfig) (*kubernetes.Clientset, error) {
+	b, err := kc.Bytes()
+	if err != nil {
+		return nil, errors.Wrap(err, "failed to convert in-memory kubeconfig to yaml")
+	}
+	cfg, err := clientcmd.RESTConfigFromKubeConfig(b)
+	if err != nil {
+		return nil, errors.Wrap(err, "failed to initialize config")
+	}
+	return kubernetes.NewForConfig(cfg)
+}

cmd/kubens/main.go

@@ -0,0 +1,44 @@
+// Copyright 2021 Google LLC
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//      http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+package main
+
+import (
+	"fmt"
+	"io"
+	"os"
+
+	"github.com/ahmetb/kubectx/internal/cmdutil"
+	"github.com/ahmetb/kubectx/internal/env"
+	"github.com/ahmetb/kubectx/internal/printer"
+	"github.com/fatih/color"
+)
+
+type Op interface {
+	Run(stdout, stderr io.Writer) error
+}
+
+func main() {
+	cmdutil.PrintDeprecatedEnvWarnings(color.Error, os.Environ())
+	op := parseArgs(os.Args[1:])
+	if err := op.Run(color.Output, color.Error); err != nil {
+		printer.Error(color.Error, err.Error())
+
+		if _, ok := os.LookupEnv(env.EnvDebug); ok {
+			// print stack trace in verbose mode
+			fmt.Fprintf(color.Error, "[DEBUG] error: %+v\n", err)
+		}
+		defer os.Exit(1)
+	}
+}

cmd/kubens/statefile.go

@@ -0,0 +1,73 @@
+// Copyright 2021 Google LLC
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//      http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+package main
+
+import (
+	"bytes"
+	"io/ioutil"
+	"os"
+	"path/filepath"
+	"runtime"
+	"strings"
+
+	"github.com/ahmetb/kubectx/internal/cmdutil"
+)
+
+var defaultDir = filepath.Join(cmdutil.HomeDir(), ".kube", "kubens")
+
+type NSFile struct {
+	dir string
+	ctx string
+}
+
+func NewNSFile(ctx string) NSFile { return NSFile{dir: defaultDir, ctx: ctx} }
+
+func (f NSFile) path() string {
+	fn := f.ctx
+	if isWindows() {
+		// bug 230: eks clusters contain ':' in ctx name, not a valid file name for win32
+		fn = strings.ReplaceAll(fn, ":", "__")
+	}
+	return filepath.Join(f.dir, fn)
+}
+
+// Load reads the previous namespace setting, or returns empty if not exists.
+func (f NSFile) Load() (string, error) {
+	b, err := ioutil.ReadFile(f.path())
+	if err != nil {
+		if os.IsNotExist(err) {
+			return "", nil
+		}
+		return "", err
+	}
+	return string(bytes.TrimSpace(b)), nil
+}
+
+// Save stores the previous namespace information in the file.
+func (f NSFile) Save(value string) error {
+	d := filepath.Dir(f.path())
+	if err := os.MkdirAll(d, 0755); err != nil {
+		return err
+	}
+	return ioutil.WriteFile(f.path(), []byte(value), 0644)
+}
+
+// isWindows determines if the process is running on windows OS.
+func isWindows() bool {
+	if os.Getenv("_FORCE_GOOS") == "windows" { // for testing
+		return true
+	}
+	return runtime.GOOS == "windows"
+}

cmd/kubens/statefile_test.go

@@ -0,0 +1,81 @@
+// Copyright 2021 Google LLC
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//      http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+package main
+
+import (
+	"io/ioutil"
+	"os"
+	"runtime"
+	"strings"
+	"testing"
+
+	"github.com/ahmetb/kubectx/internal/testutil"
+)
+
+func TestNSFile(t *testing.T) {
+	td, err := ioutil.TempDir(os.TempDir(), "")
+	if err != nil {
+		t.Fatal(err)
+	}
+	defer os.RemoveAll(td)
+
+	f := NewNSFile("foo")
+	f.dir = td
+	v, err := f.Load()
+	if err != nil {
+		t.Fatal(err)
+	}
+	if v != "" {
+		t.Fatalf("Load() expected empty; got=%v", err)
+	}
+
+	err = f.Save("bar")
+	if err != nil {
+		t.Fatalf("Save() err=%v", err)
+	}
+
+	v, err = f.Load()
+	if err != nil {
+		t.Fatal(err)
+	}
+	if expected := "bar"; v != expected {
+		t.Fatalf("Load()=\"%s\"; expected=\"%s\"", v, expected)
+	}
+}
+
+func TestNSFile_path_windows(t *testing.T) {
+	defer testutil.WithEnvVar("_FORCE_GOOS", "windows")()
+	fp := NewNSFile("a:b:c").path()
+
+	if expected := "a__b__c"; !strings.HasSuffix(fp, expected) {
+		t.Fatalf("file did not have expected ending %q: %s", expected, fp)
+	}
+}
+
+func Test_isWindows(t *testing.T) {
+	if runtime.GOOS == "windows" {
+		t.Skip("won't test this case on windows")
+	}
+
+	got := isWindows()
+	if got {
+		t.Fatalf("isWindows() returned true for %s", runtime.GOOS)
+	}
+
+	defer testutil.WithEnvVar("_FORCE_GOOS", "windows")()
+	if !isWindows() {
+		t.Fatalf("isWindows() failed to detect windows with env override.")
+	}
+}

cmd/kubens/switch.go

@@ -0,0 +1,114 @@
+// Copyright 2021 Google LLC
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//      http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+package main
+
+import (
+	"context"
+	"io"
+	"os"
+
+	"github.com/pkg/errors"
+	errors2 "k8s.io/apimachinery/pkg/api/errors"
+	metav1 "k8s.io/apimachinery/pkg/apis/meta/v1"
+
+	"github.com/ahmetb/kubectx/internal/kubeconfig"
+	"github.com/ahmetb/kubectx/internal/printer"
+)
+
+type SwitchOp struct {
+	Target string // '-' for back and forth, or NAME
+	Force  bool   // force switch even if the namespace doesn't exist
+}
+
+func (s SwitchOp) Run(_, stderr io.Writer) error {
+	kc := new(kubeconfig.Kubeconfig).WithLoader(kubeconfig.DefaultLoader)
+	defer kc.Close()
+	if err := kc.Parse(); err != nil {
+		return errors.Wrap(err, "kubeconfig error")
+	}
+
+	toNS, err := switchNamespace(kc, s.Target, s.Force)
+	if err != nil {
+		return err
+	}
+	err = printer.Success(stderr, "Active namespace is \"%s\"", printer.SuccessColor.Sprint(toNS))
+	return err
+}
+
+func switchNamespace(kc *kubeconfig.Kubeconfig, ns string, force bool) (string, error) {
+	ctx := kc.GetCurrentContext()
+	if ctx == "" {
+		return "", errors.New("current-context is not set")
+	}
+	curNS, err := kc.NamespaceOfContext(ctx)
+	if err != nil {
+		return "", errors.Wrap(err, "failed to get current namespace")
+	}
+
+	f := NewNSFile(ctx)
+	prev, err := f.Load()
+	if err != nil {
+		return "", errors.Wrap(err, "failed to load previous namespace from file")
+	}
+
+	if ns == "-" {
+		if prev == "" {
+			return "", errors.Errorf("No previous namespace found for current context (%s)", ctx)
+		}
+		ns = prev
+	}
+
+	if !force {
+		ok, err := namespaceExists(kc, ns)
+		if err != nil {
+			return "", errors.Wrap(err, "failed to query if namespace exists (is cluster accessible?)")
+		}
+		if !ok {
+			return "", errors.Errorf("no namespace exists with name \"%s\"", ns)
+		}
+	}
+
+	if err := kc.SetNamespace(ctx, ns); err != nil {
+		return "", errors.Wrapf(err, "failed to change to namespace \"%s\"", ns)
+	}
+	if err := kc.Save(); err != nil {
+		return "", errors.Wrap(err, "failed to save kubeconfig file")
+	}
+	if curNS != ns {
+		if err := f.Save(curNS); err != nil {
+			return "", errors.Wrap(err, "failed to save the previous namespace to file")
+		}
+	}
+	return ns, nil
+}
+
+func namespaceExists(kc *kubeconfig.Kubeconfig, ns string) (bool, error) {
+	// for tests
+	if os.Getenv("_MOCK_NAMESPACES") != "" {
+		return ns == "ns1" || ns == "ns2", nil
+	}
+
+	clientset, err := newKubernetesClientSet(kc)
+	if err != nil {
+		return false, errors.Wrap(err, "failed to initialize k8s REST client")
+	}
+
+	namespace, err := clientset.CoreV1().Namespaces().Get(context.Background(), ns, metav1.GetOptions{})
+	if errors2.IsNotFound(err) {
+		return false, nil
+	}
+	return namespace != nil, errors.Wrapf(err, "failed to query "+
+		"namespace %q from k8s API", ns)
+}

cmd/kubens/version.go

@@ -0,0 +1,20 @@
+package main
+
+import (
+	"fmt"
+	"io"
+
+	"github.com/pkg/errors"
+)
+
+var (
+	version = "v0.0.0+unknown" // populated by goreleaser
+)
+
+// VersionOp describes printing version string.
+type VersionOp struct{}
+
+func (_ VersionOp) Run(stdout, _ io.Writer) error {
+	_, err := fmt.Fprintf(stdout, "%s\n", version)
+	return errors.Wrap(err, "write error")
+}

completion/_kubectx.zsh

@@ -0,0 +1,20 @@
+#compdef kubectx kctx=kubectx
+
+local KUBECTX="${HOME}/.kube/kubectx"
+PREV=""
+
+local context_array=("${(@f)$(kubectl config get-contexts --output='name')}")
+local all_contexts=(\'${^context_array}\')
+
+if [ -f "$KUBECTX" ]; then
+    # show '-' only if there's a saved previous context
+    local PREV=$(cat "${KUBECTX}")
+
+    _arguments \
+      "-d:*: :(${all_contexts})" \
+      "(- *): :(- ${all_contexts})"
+else
+    _arguments \
+      "-d:*: :(${all_contexts})" \
+      "(- *): :(${all_contexts})"
+fi

completion/kubectx.fish

@@ -1,3 +1,10 @@
 # kubectx
-complete -f -c kubectx -a "- (kubectl config get-contexts --output='name')"
 
+function __fish_kubectx_arg_number -a number
+    set -l cmd (commandline -opc)
+    test (count $cmd) -eq $number
+end
+
+complete -f -c kubectx
+complete -f -x -c kubectx -n '__fish_kubectx_arg_number 1' -a "(kubectl config get-contexts --output='name')"
+complete -f -x -c kubectx -n '__fish_kubectx_arg_number 1' -a "-" -d "switch to the previous namespace in this context"

completion/kubectx.zsh

@@ -1,12 +0,0 @@
-#compdef kubectx kctx=kubectx
-
-local KUBECTX="${HOME}/.kube/kubectx"
-PREV=""
-if [ -f "$KUBECTX" ]; then
-    # show '-' only if there's a saved previous context
-    local PREV=$(cat "${KUBECTX}")
-    _arguments "1: :((- \
-        $(kubectl config get-contexts --output='name')))"
-else
-    _arguments "1: :($(kubectl config get-contexts --output='name'))"
-fi

completion/kubens.fish

@@ -1,3 +1,12 @@
 # kubens
-complete -f -c kubens -a "(kubectl get ns -o=custom-columns=NAME:.metadata.name --no-headers)"
 
+function __fish_kubens_arg_number -a number
+    set -l cmd (commandline -opc)
+    test (count $cmd) -eq $number
+end
+
+complete -f -c kubens
+complete -f -x -c kubens -n '__fish_kubens_arg_number 1' -a "(kubectl get ns -o=custom-columns=NAME:.metadata.name --no-headers)"
+complete -f -x -c kubens -n '__fish_kubens_arg_number 1' -a "-" -d "switch to the previous namespace in this context"
+complete -f -x -c kubens -n '__fish_kubens_arg_number 1' -s c -l current -d "show the current namespace"
+complete -f -x -c kubens -n '__fish_kubens_arg_number 1' -s h -l help -d "show the help message"

go.mod

@@ -0,0 +1,56 @@
+module github.com/ahmetb/kubectx
+
+go 1.20
+
+require (
+	facette.io/natsort v0.0.0-20181210072756-2cd4dd1e2dcb
+	github.com/fatih/color v1.9.0
+	github.com/google/go-cmp v0.5.9
+	github.com/mattn/go-isatty v0.0.14
+	github.com/pkg/errors v0.9.1
+	k8s.io/apimachinery v0.28.5
+	k8s.io/client-go v0.28.5
+	sigs.k8s.io/kustomize/kyaml v0.16.0
+)
+
+require (
+	github.com/davecgh/go-spew v1.1.1 // indirect
+	github.com/emicklei/go-restful/v3 v3.9.0 // indirect
+	github.com/go-errors/errors v1.4.2 // indirect
+	github.com/go-logr/logr v1.2.4 // indirect
+	github.com/go-openapi/jsonpointer v0.19.6 // indirect
+	github.com/go-openapi/jsonreference v0.20.2 // indirect
+	github.com/go-openapi/swag v0.22.3 // indirect
+	github.com/gogo/protobuf v1.3.2 // indirect
+	github.com/golang/protobuf v1.5.3 // indirect
+	github.com/google/gnostic-models v0.6.8 // indirect
+	github.com/google/gofuzz v1.2.0 // indirect
+	github.com/google/uuid v1.3.0 // indirect
+	github.com/imdario/mergo v0.3.9 // indirect
+	github.com/josharian/intern v1.0.0 // indirect
+	github.com/json-iterator/go v1.1.12 // indirect
+	github.com/mailru/easyjson v0.7.7 // indirect
+	github.com/mattn/go-colorable v0.1.4 // indirect
+	github.com/modern-go/concurrent v0.0.0-20180306012644-bacd9c7ef1dd // indirect
+	github.com/modern-go/reflect2 v1.0.2 // indirect
+	github.com/munnerz/goautoneg v0.0.0-20191010083416-a7dc8b61c822 // indirect
+	github.com/spf13/pflag v1.0.5 // indirect
+	golang.org/x/net v0.17.0 // indirect
+	golang.org/x/oauth2 v0.8.0 // indirect
+	golang.org/x/sys v0.13.0 // indirect
+	golang.org/x/term v0.13.0 // indirect
+	golang.org/x/text v0.13.0 // indirect
+	golang.org/x/time v0.3.0 // indirect
+	google.golang.org/appengine v1.6.7 // indirect
+	google.golang.org/protobuf v1.31.0 // indirect
+	gopkg.in/inf.v0 v0.9.1 // indirect
+	gopkg.in/yaml.v2 v2.4.0 // indirect
+	gopkg.in/yaml.v3 v3.0.1 // indirect
+	k8s.io/api v0.28.5 // indirect
+	k8s.io/klog/v2 v2.100.1 // indirect
+	k8s.io/kube-openapi v0.0.0-20230717233707-2695361300d9 // indirect
+	k8s.io/utils v0.0.0-20230505201702-9f6742963106 // indirect
+	sigs.k8s.io/json v0.0.0-20221116044647-bc3834ca7abd // indirect
+	sigs.k8s.io/structured-merge-diff/v4 v4.2.3 // indirect
+	sigs.k8s.io/yaml v1.4.0 // indirect
+)

go.sum

@@ -0,0 +1,167 @@
+facette.io/natsort v0.0.0-20181210072756-2cd4dd1e2dcb h1:1pSweJFeR3Pqx7uoelppkzeegfUBXL6I2FFAbfXw570=
+facette.io/natsort v0.0.0-20181210072756-2cd4dd1e2dcb/go.mod h1:npRYmtaITVom7rcSo+pRURltHSG2r4TQM1cdqJ2dUB0=
+github.com/creack/pty v1.1.9/go.mod h1:oKZEueFk5CKHvIhNR5MUki03XCEU+Q6VDXinZuGJ33E=
+github.com/davecgh/go-spew v1.1.0/go.mod h1:J7Y8YcW2NihsgmVo/mv3lAwl/skON4iLHjSsI+c5H38=
+github.com/davecgh/go-spew v1.1.1 h1:vj9j/u1bqnvCEfJOwUhtlOARqs3+rkHYY13jYWTU97c=
+github.com/davecgh/go-spew v1.1.1/go.mod h1:J7Y8YcW2NihsgmVo/mv3lAwl/skON4iLHjSsI+c5H38=
+github.com/emicklei/go-restful/v3 v3.9.0 h1:XwGDlfxEnQZzuopoqxwSEllNcCOM9DhhFyhFIIGKwxE=
+github.com/emicklei/go-restful/v3 v3.9.0/go.mod h1:6n3XBCmQQb25CM2LCACGz8ukIrRry+4bhvbpWn3mrbc=
+github.com/fatih/color v1.9.0 h1:8xPHl4/q1VyqGIPif1F+1V3Y3lSmrq01EabUW3CoW5s=
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+github.com/go-errors/errors v1.4.2 h1:J6MZopCL4uSllY1OfXM374weqZFFItUbrImctkmUxIA=
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internal/cmdutil/deprecated.go

@@ -0,0 +1,36 @@
+// Copyright 2021 Google LLC
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//      http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+package cmdutil
+
+import (
+	"io"
+	"strings"
+
+	"github.com/ahmetb/kubectx/internal/printer"
+)
+
+func PrintDeprecatedEnvWarnings(out io.Writer, vars []string) {
+	for _, vv := range vars {
+		parts := strings.SplitN(vv, "=", 2)
+		if len(parts) != 2 {
+			continue
+		}
+		key := parts[0]
+
+		if key == `KUBECTX_CURRENT_FGCOLOR` || key == `KUBECTX_CURRENT_BGCOLOR` {
+			printer.Warning(out, "%s environment variable is now deprecated", key)
+		}
+	}
+}

internal/cmdutil/deprecated_test.go

@@ -0,0 +1,48 @@
+// Copyright 2021 Google LLC
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//      http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+package cmdutil
+
+import (
+	"bytes"
+	"strings"
+	"testing"
+)
+
+func TestPrintDeprecatedEnvWarnings_noDeprecatedVars(t *testing.T) {
+	var out bytes.Buffer
+	PrintDeprecatedEnvWarnings(&out, []string{
+		"A=B",
+		"PATH=/foo:/bar:/bin",
+	})
+	if v := out.String(); len(v) > 0 {
+		t.Fatalf("something written to buf: %v", v)
+	}
+}
+
+func TestPrintDeprecatedEnvWarnings_bgColors(t *testing.T) {
+	var out bytes.Buffer
+
+	PrintDeprecatedEnvWarnings(&out, []string{
+		"KUBECTX_CURRENT_FGCOLOR=1",
+		"KUBECTX_CURRENT_BGCOLOR=2",
+	})
+	v := out.String()
+	if !strings.Contains(v, "KUBECTX_CURRENT_FGCOLOR") {
+		t.Fatalf("output doesn't contain 'KUBECTX_CURRENT_FGCOLOR': \"%s\"", v)
+	}
+	if !strings.Contains(v, "KUBECTX_CURRENT_BGCOLOR") {
+		t.Fatalf("output doesn't contain 'KUBECTX_CURRENT_BGCOLOR': \"%s\"", v)
+	}
+}

internal/cmdutil/interactive.go

@@ -0,0 +1,44 @@
+// Copyright 2021 Google LLC
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//      http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+package cmdutil
+
+import (
+	"os"
+	"os/exec"
+
+	"github.com/mattn/go-isatty"
+
+	"github.com/ahmetb/kubectx/internal/env"
+)
+
+// isTerminal determines if given fd is a TTY.
+func isTerminal(fd *os.File) bool {
+	return isatty.IsTerminal(fd.Fd())
+}
+
+// fzfInstalled determines if fzf(1) is in PATH.
+func fzfInstalled() bool {
+	v, _ := exec.LookPath("fzf")
+	if v != "" {
+		return true
+	}
+	return false
+}
+
+// IsInteractiveMode determines if we can do choosing with fzf.
+func IsInteractiveMode(stdout *os.File) bool {
+	v := os.Getenv(env.EnvFZFIgnore)
+	return v == "" && isTerminal(stdout) && fzfInstalled()
+}

internal/cmdutil/util.go

@@ -0,0 +1,40 @@
+// Copyright 2021 Google LLC
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//      http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+package cmdutil
+
+import (
+	"os"
+
+	"github.com/pkg/errors"
+)
+
+func HomeDir() string {
+	home := os.Getenv("HOME")
+	if home == "" {
+		home = os.Getenv("USERPROFILE") // windows
+	}
+	return home
+}
+
+// IsNotFoundErr determines if the underlying error is os.IsNotExist. Right now
+// errors from github.com/pkg/errors doesn't work with os.IsNotExist.
+func IsNotFoundErr(err error) bool {
+	for e := err; e != nil; e = errors.Unwrap(e) {
+		if os.IsNotExist(e) {
+			return true
+		}
+	}
+	return false
+}

internal/cmdutil/util_test.go

@@ -0,0 +1,80 @@
+// Copyright 2021 Google LLC
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//      http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+package cmdutil
+
+import (
+	"testing"
+
+	"github.com/ahmetb/kubectx/internal/testutil"
+)
+
+func Test_homeDir(t *testing.T) {
+	type env struct{ k, v string }
+	cases := []struct {
+		name string
+		envs []env
+		want string
+	}{
+		{
+			name: "don't use XDG_CACHE_HOME as homedir",
+			envs: []env{
+				{"XDG_CACHE_HOME", "xdg"},
+				{"HOME", "home"},
+			},
+			want: "home",
+		},
+		{
+			name: "HOME over USERPROFILE",
+			envs: []env{
+				{"HOME", "home"},
+				{"USERPROFILE", "up"},
+			},
+			want: "home",
+		},
+		{
+			name: "only USERPROFILE available",
+			envs: []env{
+				{"HOME", ""},
+				{"USERPROFILE", "up"},
+			},
+			want: "up",
+		},
+		{
+			name: "none available",
+			envs: []env{
+				{"HOME", ""},
+				{"USERPROFILE", ""},
+			},
+			want: "",
+		},
+	}
+
+	for _, c := range cases {
+		t.Run(c.name, func(tt *testing.T) {
+			var unsets []func()
+			for _, e := range c.envs {
+				unsets = append(unsets, testutil.WithEnvVar(e.k, e.v))
+			}
+
+			got := HomeDir()
+			if got != c.want {
+				t.Errorf("expected:%q got:%q", c.want, got)
+			}
+			for _, u := range unsets {
+				u()
+			}
+		})
+	}
+}

internal/env/constants.go

@@ -0,0 +1,34 @@
+// Copyright 2021 Google LLC
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//      http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+package env
+
+const (
+	// EnvFZFIgnore describes the environment variable to set to disable
+	// interactive context selection when fzf is installed.
+	EnvFZFIgnore = "KUBECTX_IGNORE_FZF"
+
+	// EnvNoColor describes the environment variable to disable color usage
+	// when printing current context in a list.
+	EnvNoColor = `NO_COLOR`
+
+	// EnvForceColor describes the "internal" environment variable to force
+	// color usage to show current context in a list.
+	EnvForceColor = `_KUBECTX_FORCE_COLOR`
+
+	// EnvDebug describes the internal environment variable for more verbose logging.
+	EnvDebug = `DEBUG`
+
+	EnvIsolatedShell = "KUBECTX_ISOLATED_SHELL"
+)

internal/kubeconfig/contextmodify.go

@@ -0,0 +1,58 @@
+// Copyright 2021 Google LLC
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//      http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+package kubeconfig
+
+import (
+	"errors"
+
+	"sigs.k8s.io/kustomize/kyaml/yaml"
+)
+
+func (k *Kubeconfig) DeleteContextEntry(deleteName string) error {
+	contexts, err := k.contextsNode()
+	if err != nil {
+		return err
+	}
+	if err := contexts.PipeE(
+		yaml.ElementSetter{
+			Keys:   []string{"name"},
+			Values: []string{deleteName},
+		},
+	); err != nil {
+		return err
+	}
+	return nil
+}
+
+func (k *Kubeconfig) ModifyCurrentContext(name string) error {
+	if err := k.config.PipeE(yaml.SetField("current-context", yaml.NewScalarRNode(name))); err != nil {
+		return err
+	}
+	return nil
+}
+
+func (k *Kubeconfig) ModifyContextName(old, new string) error {
+	context, err := k.config.Pipe(yaml.Lookup("contexts", "[name="+old+"]"))
+	if err != nil {
+		return err
+	}
+	if context == nil {
+		return errors.New("\"contexts\" entry is nil")
+	}
+	if err := context.PipeE(yaml.SetField("name", yaml.NewScalarRNode(new))); err != nil {
+		return err
+	}
+	return nil
+}

internal/kubeconfig/contextmodify_test.go

@@ -0,0 +1,180 @@
+// Copyright 2021 Google LLC
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//      http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+package kubeconfig
+
+import (
+	"testing"
+
+	"github.com/google/go-cmp/cmp"
+
+	"github.com/ahmetb/kubectx/internal/testutil"
+)
+
+func TestKubeconfig_DeleteContextEntry_errors(t *testing.T) {
+	kc := new(Kubeconfig).WithLoader(WithMockKubeconfigLoader(`[1, 2, 3]`))
+	_ = kc.Parse()
+	err := kc.DeleteContextEntry("foo")
+	if err == nil {
+		t.Fatal("supposed to fail on non-mapping nodes")
+	}
+
+	kc = new(Kubeconfig).WithLoader(WithMockKubeconfigLoader(`a: b`))
+	_ = kc.Parse()
+	err = kc.DeleteContextEntry("foo")
+	if err == nil {
+		t.Fatal("supposed to fail if contexts key does not exist")
+	}
+
+	kc = new(Kubeconfig).WithLoader(WithMockKubeconfigLoader(`contexts: "some string"`))
+	_ = kc.Parse()
+	err = kc.DeleteContextEntry("foo")
+	if err == nil {
+		t.Fatal("supposed to fail if contexts key is not an array")
+	}
+}
+
+func TestKubeconfig_DeleteContextEntry(t *testing.T) {
+	test := WithMockKubeconfigLoader(
+		testutil.KC().WithCtxs(
+			testutil.Ctx("c1"),
+			testutil.Ctx("c2"),
+			testutil.Ctx("c3")).ToYAML(t))
+	kc := new(Kubeconfig).WithLoader(test)
+	if err := kc.Parse(); err != nil {
+		t.Fatal(err)
+	}
+	if err := kc.DeleteContextEntry("c1"); err != nil {
+		t.Fatal(err)
+	}
+	if err := kc.Save(); err != nil {
+		t.Fatal(err)
+	}
+
+	expected := testutil.KC().WithCtxs(
+		testutil.Ctx("c2"),
+		testutil.Ctx("c3")).ToYAML(t)
+	out := test.Output()
+	if diff := cmp.Diff(expected, out); diff != "" {
+		t.Fatalf("diff: %s", diff)
+	}
+}
+
+func TestKubeconfig_ModifyCurrentContext_fieldExists(t *testing.T) {
+	test := WithMockKubeconfigLoader(
+		testutil.KC().WithCurrentCtx("abc").Set("field1", "value1").ToYAML(t))
+	kc := new(Kubeconfig).WithLoader(test)
+	if err := kc.Parse(); err != nil {
+		t.Fatal(err)
+	}
+	if err := kc.ModifyCurrentContext("foo"); err != nil {
+		t.Fatal(err)
+	}
+	if err := kc.Save(); err != nil {
+		t.Fatal(err)
+	}
+
+	expected := testutil.KC().WithCurrentCtx("foo").Set("field1", "value1").ToYAML(t)
+	out := test.Output()
+	if diff := cmp.Diff(expected, out); diff != "" {
+		t.Fatalf("diff: %s", diff)
+	}
+}
+
+func TestKubeconfig_ModifyCurrentContext_fieldMissing(t *testing.T) {
+	test := WithMockKubeconfigLoader(`f1: v1`)
+	kc := new(Kubeconfig).WithLoader(test)
+	if err := kc.Parse(); err != nil {
+		t.Fatal(err)
+	}
+	if err := kc.ModifyCurrentContext("foo"); err != nil {
+		t.Fatal(err)
+	}
+	if err := kc.Save(); err != nil {
+		t.Fatal(err)
+	}
+
+	expected := `f1: v1
+current-context: foo
+`
+	out := test.Output()
+	if diff := cmp.Diff(expected, out); diff != "" {
+		t.Fatalf("diff: %s", diff)
+	}
+}
+
+func TestKubeconfig_ModifyContextName_noContextsEntryError(t *testing.T) {
+	// no context entries
+	test := WithMockKubeconfigLoader(`a: b`)
+	kc := new(Kubeconfig).WithLoader(test)
+	if err := kc.Parse(); err != nil {
+		t.Fatal(err)
+	}
+	if err := kc.ModifyContextName("c1", "c2"); err == nil {
+		t.Fatal("was expecting error for no 'contexts' entry; got nil")
+	}
+}
+
+func TestKubeconfig_ModifyContextName_contextsEntryNotSequenceError(t *testing.T) {
+	// no context entries
+	test := WithMockKubeconfigLoader(
+		`contexts: "hello"`)
+	kc := new(Kubeconfig).WithLoader(test)
+	if err := kc.Parse(); err != nil {
+		t.Fatal(err)
+	}
+	if err := kc.ModifyContextName("c1", "c2"); err == nil {
+		t.Fatal("was expecting error for 'context entry not a sequence'; got nil")
+	}
+}
+
+func TestKubeconfig_ModifyContextName_noChange(t *testing.T) {
+	test := WithMockKubeconfigLoader(testutil.KC().WithCtxs(
+		testutil.Ctx("c1"),
+		testutil.Ctx("c2"),
+		testutil.Ctx("c3")).ToYAML(t))
+	kc := new(Kubeconfig).WithLoader(test)
+	if err := kc.Parse(); err != nil {
+		t.Fatal(err)
+	}
+	if err := kc.ModifyContextName("c5", "c6"); err == nil {
+		t.Fatal("was expecting error for 'no changes made'")
+	}
+}
+
+func TestKubeconfig_ModifyContextName(t *testing.T) {
+	test := WithMockKubeconfigLoader(testutil.KC().WithCtxs(
+		testutil.Ctx("c1"),
+		testutil.Ctx("c2"),
+		testutil.Ctx("c3")).ToYAML(t))
+	kc := new(Kubeconfig).WithLoader(test)
+	if err := kc.Parse(); err != nil {
+		t.Fatal(err)
+	}
+	if err := kc.ModifyContextName("c1", "ccc"); err != nil {
+		t.Fatal(err)
+	}
+	if err := kc.Save(); err != nil {
+		t.Fatal(err)
+	}
+
+	expected := testutil.KC().WithCtxs(
+		testutil.Ctx("ccc"),
+		testutil.Ctx("c2"),
+		testutil.Ctx("c3")).ToYAML(t)
+	out := test.Output()
+	if diff := cmp.Diff(expected, out); diff != "" {
+		t.Fatalf("diff: %s", diff)
+	}
+}

internal/kubeconfig/contexts.go

@@ -0,0 +1,70 @@
+// Copyright 2021 Google LLC
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//      http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+package kubeconfig
+
+import (
+	"github.com/pkg/errors"
+	"sigs.k8s.io/kustomize/kyaml/yaml"
+)
+
+func (k *Kubeconfig) contextsNode() (*yaml.RNode, error) {
+	contexts, err := k.config.Pipe(yaml.Get("contexts"))
+	if err != nil {
+		return nil, err
+	}
+	if contexts == nil {
+		return nil, errors.New("\"contexts\" entry is nil")
+	} else if contexts.YNode().Kind != yaml.SequenceNode {
+		return nil, errors.New("\"contexts\" is not a sequence node")
+	}
+	return contexts, nil
+}
+
+func (k *Kubeconfig) contextNode(name string) (*yaml.RNode, error) {
+	contexts, err := k.contextsNode()
+	if err != nil {
+		return nil, err
+	}
+	context, err := contexts.Pipe(yaml.Lookup("[name=" + name + "]"))
+	if err != nil {
+		return nil, err
+	}
+	if context == nil {
+		return nil, errors.Errorf("context with name \"%s\" not found", name)
+	}
+	return context, nil
+}
+
+func (k *Kubeconfig) ContextNames() []string {
+	contexts, err := k.config.Pipe(yaml.Get("contexts"))
+	if err != nil {
+		return nil
+	}
+	names, err := contexts.ElementValues("name")
+	if err != nil {
+		return nil
+	}
+	return names
+}
+
+func (k *Kubeconfig) ContextExists(name string) bool {
+	ctxNames := k.ContextNames()
+	for _, v := range ctxNames {
+		if v == name {
+			return true
+		}
+	}
+	return false
+}

internal/kubeconfig/contexts_test.go

@@ -0,0 +1,89 @@
+// Copyright 2021 Google LLC
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//      http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+package kubeconfig
+
+import (
+	"testing"
+
+	"github.com/google/go-cmp/cmp"
+
+	"github.com/ahmetb/kubectx/internal/testutil"
+)
+
+func TestKubeconfig_ContextNames(t *testing.T) {
+	tl := WithMockKubeconfigLoader(
+		testutil.KC().WithCtxs(
+			testutil.Ctx("abc"),
+			testutil.Ctx("def"),
+			testutil.Ctx("ghi")).Set("field1", map[string]string{"bar": "zoo"}).ToYAML(t))
+	kc := new(Kubeconfig).WithLoader(tl)
+	if err := kc.Parse(); err != nil {
+		t.Fatal(err)
+	}
+
+	ctx := kc.ContextNames()
+	expected := []string{"abc", "def", "ghi"}
+	if diff := cmp.Diff(expected, ctx); diff != "" {
+		t.Fatalf("%s", diff)
+	}
+}
+
+func TestKubeconfig_ContextNames_noContextsEntry(t *testing.T) {
+	tl := WithMockKubeconfigLoader(`a: b`)
+	kc := new(Kubeconfig).WithLoader(tl)
+	if err := kc.Parse(); err != nil {
+		t.Fatal(err)
+	}
+	ctx := kc.ContextNames()
+	var expected []string = nil
+	if diff := cmp.Diff(expected, ctx); diff != "" {
+		t.Fatalf("%s", diff)
+	}
+}
+
+func TestKubeconfig_ContextNames_nonArrayContextsEntry(t *testing.T) {
+	tl := WithMockKubeconfigLoader(`contexts: "hello"`)
+	kc := new(Kubeconfig).WithLoader(tl)
+	if err := kc.Parse(); err != nil {
+		t.Fatal(err)
+	}
+	ctx := kc.ContextNames()
+	var expected []string = nil
+	if diff := cmp.Diff(expected, ctx); diff != "" {
+		t.Fatalf("%s", diff)
+	}
+}
+
+func TestKubeconfig_CheckContextExists(t *testing.T) {
+	tl := WithMockKubeconfigLoader(
+		testutil.KC().WithCtxs(
+			testutil.Ctx("c1"),
+			testutil.Ctx("c2")).ToYAML(t))
+
+	kc := new(Kubeconfig).WithLoader(tl)
+	if err := kc.Parse(); err != nil {
+		t.Fatal(err)
+	}
+
+	if !kc.ContextExists("c1") {
+		t.Fatal("c1 actually exists; reported false")
+	}
+	if !kc.ContextExists("c2") {
+		t.Fatal("c2 actually exists; reported false")
+	}
+	if kc.ContextExists("c3") {
+		t.Fatal("c3 does not exist; but reported true")
+	}
+}

internal/kubeconfig/currentcontext.go

@@ -0,0 +1,33 @@
+// Copyright 2021 Google LLC
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//      http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+package kubeconfig
+
+import (
+	"sigs.k8s.io/kustomize/kyaml/yaml"
+)
+
+// GetCurrentContext returns "current-context" value in given
+// kubeconfig object Node, or returns "" if not found.
+func (k *Kubeconfig) GetCurrentContext() string {
+	v, err := k.config.Pipe(yaml.Get("current-context"))
+	if err != nil {
+		return ""
+	}
+	return yaml.GetValue(v)
+}
+
+func (k *Kubeconfig) UnsetCurrentContext() error {
+	return k.config.PipeE(yaml.SetField("current-context", yaml.NewStringRNode("")))
+}

internal/kubeconfig/currentcontext_test.go

@@ -0,0 +1,69 @@
+// Copyright 2021 Google LLC
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//      http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+package kubeconfig
+
+import (
+	"testing"
+
+	"github.com/ahmetb/kubectx/internal/testutil"
+)
+
+func TestKubeconfig_GetCurrentContext(t *testing.T) {
+	tl := WithMockKubeconfigLoader(`current-context: foo`)
+	kc := new(Kubeconfig).WithLoader(tl)
+	if err := kc.Parse(); err != nil {
+		t.Fatal(err)
+	}
+	v := kc.GetCurrentContext()
+
+	expected := "foo"
+	if v != expected {
+		t.Fatalf("expected=\"%s\"; got=\"%s\"", expected, v)
+	}
+}
+
+func TestKubeconfig_GetCurrentContext_missingField(t *testing.T) {
+	tl := WithMockKubeconfigLoader(`abc: def`)
+	kc := new(Kubeconfig).WithLoader(tl)
+	if err := kc.Parse(); err != nil {
+		t.Fatal(err)
+	}
+	v := kc.GetCurrentContext()
+
+	expected := ""
+	if v != expected {
+		t.Fatalf("expected=\"%s\"; got=\"%s\"", expected, v)
+	}
+}
+
+func TestKubeconfig_UnsetCurrentContext(t *testing.T) {
+	tl := WithMockKubeconfigLoader(testutil.KC().WithCurrentCtx("foo").ToYAML(t))
+	kc := new(Kubeconfig).WithLoader(tl)
+	if err := kc.Parse(); err != nil {
+		t.Fatal(err)
+	}
+	if err := kc.UnsetCurrentContext(); err != nil {
+		t.Fatal(err)
+	}
+	if err := kc.Save(); err != nil {
+		t.Fatal(err)
+	}
+
+	out := tl.Output()
+	expected := testutil.KC().WithCurrentCtx("").ToYAML(t)
+	if out != expected {
+		t.Fatalf("expected=\"%s\"; got=\"%s\"", expected, out)
+	}
+}

internal/kubeconfig/helper_test.go

@@ -0,0 +1,39 @@
+// Copyright 2021 Google LLC
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//      http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+package kubeconfig
+
+import (
+	"bytes"
+	"io"
+	"strings"
+)
+
+type MockKubeconfigLoader struct {
+	in  io.Reader
+	out bytes.Buffer
+}
+
+func (t *MockKubeconfigLoader) Read(p []byte) (n int, err error)  { return t.in.Read(p) }
+func (t *MockKubeconfigLoader) Write(p []byte) (n int, err error) { return t.out.Write(p) }
+func (t *MockKubeconfigLoader) Close() error                      { return nil }
+func (t *MockKubeconfigLoader) Reset() error                      { return nil }
+func (t *MockKubeconfigLoader) Load() ([]ReadWriteResetCloser, error) {
+	return []ReadWriteResetCloser{ReadWriteResetCloser(t)}, nil
+}
+func (t *MockKubeconfigLoader) Output() string { return t.out.String() }
+
+func WithMockKubeconfigLoader(kubecfg string) *MockKubeconfigLoader {
+	return &MockKubeconfigLoader{in: strings.NewReader(kubecfg)}
+}

internal/kubeconfig/kubeconfig.go

@@ -0,0 +1,90 @@
+// Copyright 2021 Google LLC
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//      http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+package kubeconfig
+
+import (
+	"io"
+
+	"github.com/pkg/errors"
+	"sigs.k8s.io/kustomize/kyaml/yaml"
+)
+
+type ReadWriteResetCloser interface {
+	io.ReadWriteCloser
+
+	// Reset truncates the file and seeks to the beginning of the file.
+	Reset() error
+}
+
+type Loader interface {
+	Load() ([]ReadWriteResetCloser, error)
+}
+
+type Kubeconfig struct {
+	loader Loader
+
+	f      ReadWriteResetCloser
+	config *yaml.RNode
+}
+
+func (k *Kubeconfig) WithLoader(l Loader) *Kubeconfig {
+	k.loader = l
+	return k
+}
+
+func (k *Kubeconfig) Close() error {
+	if k.f == nil {
+		return nil
+	}
+	return k.f.Close()
+}
+
+func (k *Kubeconfig) Parse() error {
+	files, err := k.loader.Load()
+	if err != nil {
+		return errors.Wrap(err, "failed to load")
+	}
+
+	// TODO since we don't support multiple kubeconfig files at the moment, there's just 1 file
+	f := files[0]
+
+	k.f = f
+	var v yaml.Node
+	if err := yaml.NewDecoder(f).Decode(&v); err != nil {
+		return errors.Wrap(err, "failed to decode")
+	}
+	k.config = yaml.NewRNode(&v)
+	if k.config.YNode().Kind != yaml.MappingNode {
+		return errors.New("kubeconfig file is not a map document")
+	}
+	return nil
+}
+
+func (k *Kubeconfig) Bytes() ([]byte, error) {
+	str, err := k.config.String()
+	if err != nil {
+		return nil, err
+	}
+	return []byte(str), nil
+}
+
+func (k *Kubeconfig) Save() error {
+	if err := k.f.Reset(); err != nil {
+		return errors.Wrap(err, "failed to reset file")
+	}
+	enc := yaml.NewEncoder(k.f)
+	enc.SetIndent(0)
+	return enc.Encode(k.config.YNode())
+}

internal/kubeconfig/kubeconfig_test.go

@@ -0,0 +1,67 @@
+// Copyright 2021 Google LLC
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//      http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+package kubeconfig
+
+import (
+	"testing"
+
+	"github.com/google/go-cmp/cmp"
+
+	"github.com/ahmetb/kubectx/internal/testutil"
+)
+
+func TestParse(t *testing.T) {
+	err := new(Kubeconfig).WithLoader(WithMockKubeconfigLoader(`a: [1, 2`)).Parse()
+	if err == nil {
+		t.Fatal("expected error from bad yaml")
+	}
+
+	err = new(Kubeconfig).WithLoader(WithMockKubeconfigLoader(`[1, 2, 3]`)).Parse()
+	if err == nil {
+		t.Fatal("expected error from not-mapping root node")
+	}
+
+	err = new(Kubeconfig).WithLoader(WithMockKubeconfigLoader(`current-context: foo`)).Parse()
+	if err != nil {
+		t.Fatal(err)
+	}
+
+	err = new(Kubeconfig).WithLoader(WithMockKubeconfigLoader(testutil.KC().
+		WithCurrentCtx("foo").
+		WithCtxs().ToYAML(t))).Parse()
+	if err != nil {
+		t.Fatal(err)
+	}
+}
+
+func TestSave(t *testing.T) {
+	in := "a: [1, 2, 3]\n"
+	test := WithMockKubeconfigLoader(in)
+	kc := new(Kubeconfig).WithLoader(test)
+	defer kc.Close()
+	if err := kc.Parse(); err != nil {
+		t.Fatal(err)
+	}
+	if err := kc.ModifyCurrentContext("hello"); err != nil {
+		t.Fatal(err)
+	}
+	if err := kc.Save(); err != nil {
+		t.Fatal(err)
+	}
+	expected := "a: [1, 2, 3]\ncurrent-context: hello\n"
+	if diff := cmp.Diff(expected, test.Output()); diff != "" {
+		t.Fatal(diff)
+	}
+}

internal/kubeconfig/kubeconfigloader.go

@@ -0,0 +1,76 @@
+// Copyright 2021 Google LLC
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//      http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+package kubeconfig
+
+import (
+	"github.com/ahmetb/kubectx/internal/cmdutil"
+	"os"
+	"path/filepath"
+
+	"github.com/pkg/errors"
+)
+
+var (
+	DefaultLoader Loader = new(StandardKubeconfigLoader)
+)
+
+type StandardKubeconfigLoader struct{}
+
+type kubeconfigFile struct{ *os.File }
+
+func (*StandardKubeconfigLoader) Load() ([]ReadWriteResetCloser, error) {
+	cfgPath, err := kubeconfigPath()
+	if err != nil {
+		return nil, errors.Wrap(err, "cannot determine kubeconfig path")
+	}
+
+	f, err := os.OpenFile(cfgPath, os.O_RDWR, 0)
+	if err != nil {
+		if os.IsNotExist(err) {
+			return nil, errors.Wrap(err, "kubeconfig file not found")
+		}
+		return nil, errors.Wrap(err, "failed to open file")
+	}
+
+	// TODO we'll return all kubeconfig files when we start implementing multiple kubeconfig support
+	return []ReadWriteResetCloser{ReadWriteResetCloser(&kubeconfigFile{f})}, nil
+}
+
+func (kf *kubeconfigFile) Reset() error {
+	if err := kf.Truncate(0); err != nil {
+		return errors.Wrap(err, "failed to truncate file")
+	}
+	_, err := kf.Seek(0, 0)
+	return errors.Wrap(err, "failed to seek in file")
+}
+
+func kubeconfigPath() (string, error) {
+	// KUBECONFIG env var
+	if v := os.Getenv("KUBECONFIG"); v != "" {
+		list := filepath.SplitList(v)
+		if len(list) > 1 {
+			// TODO KUBECONFIG=file1:file2 currently not supported
+			return "", errors.New("multiple files in KUBECONFIG are currently not supported")
+		}
+		return v, nil
+	}
+
+	// default path
+	home := cmdutil.HomeDir()
+	if home == "" {
+		return "", errors.New("HOME or USERPROFILE environment variable not set")
+	}
+	return filepath.Join(home, ".kube", "config"), nil
+}

internal/kubeconfig/kubeconfigloader_test.go

@@ -0,0 +1,83 @@
+// Copyright 2021 Google LLC
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//      http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+package kubeconfig
+
+import (
+	"github.com/ahmetb/kubectx/internal/cmdutil"
+	"os"
+	"path/filepath"
+	"strings"
+	"testing"
+
+	"github.com/ahmetb/kubectx/internal/testutil"
+)
+
+func Test_kubeconfigPath(t *testing.T) {
+	defer testutil.WithEnvVar("HOME", "/x/y/z")()
+
+	expected := filepath.FromSlash("/x/y/z/.kube/config")
+	got, err := kubeconfigPath()
+	if err != nil {
+		t.Fatal(err)
+	}
+	if got != expected {
+		t.Fatalf("got=%q expected=%q", got, expected)
+	}
+}
+
+func Test_kubeconfigPath_noEnvVars(t *testing.T) {
+	defer testutil.WithEnvVar("XDG_CACHE_HOME", "")()
+	defer testutil.WithEnvVar("HOME", "")()
+	defer testutil.WithEnvVar("USERPROFILE", "")()
+
+	_, err := kubeconfigPath()
+	if err == nil {
+		t.Fatalf("expected error")
+	}
+}
+
+func Test_kubeconfigPath_envOvveride(t *testing.T) {
+	defer testutil.WithEnvVar("KUBECONFIG", "foo")()
+
+	v, err := kubeconfigPath()
+	if err != nil {
+		t.Fatal(err)
+	}
+	if expected := "foo"; v != expected {
+		t.Fatalf("expected=%q, got=%q", expected, v)
+	}
+}
+
+func Test_kubeconfigPath_envOvverideDoesNotSupportPathSeparator(t *testing.T) {
+	path := strings.Join([]string{"file1", "file2"}, string(os.PathListSeparator))
+	defer testutil.WithEnvVar("KUBECONFIG", path)()
+
+	_, err := kubeconfigPath()
+	if err == nil {
+		t.Fatal("expected error")
+	}
+}
+
+func TestStandardKubeconfigLoader_returnsNotFoundErr(t *testing.T) {
+	defer testutil.WithEnvVar("KUBECONFIG", "foo")()
+	kc := new(Kubeconfig).WithLoader(DefaultLoader)
+	err := kc.Parse()
+	if err == nil {
+		t.Fatal("expected err")
+	}
+	if !cmdutil.IsNotFoundErr(err) {
+		t.Fatalf("expected ENOENT error; got=%v", err)
+	}
+}

internal/kubeconfig/namespace.go

@@ -0,0 +1,49 @@
+// Copyright 2021 Google LLC
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//      http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+package kubeconfig
+
+import (
+	"sigs.k8s.io/kustomize/kyaml/yaml"
+)
+
+const (
+	defaultNamespace = "default"
+)
+
+func (k *Kubeconfig) NamespaceOfContext(contextName string) (string, error) {
+	ctx, err := k.contextNode(contextName)
+	if err != nil {
+		return "", err
+	}
+	namespace, err := ctx.Pipe(yaml.Lookup("context", "namespace"))
+	if namespace == nil || err != nil {
+		return defaultNamespace, err
+	}
+	return yaml.GetValue(namespace), nil
+}
+
+func (k *Kubeconfig) SetNamespace(ctxName string, ns string) error {
+	ctx, err := k.contextNode(ctxName)
+	if err != nil {
+		return err
+	}
+	if err := ctx.PipeE(
+		yaml.LookupCreate(yaml.MappingNode, "context"),
+		yaml.SetField("namespace", yaml.NewStringRNode(ns)),
+	); err != nil {
+		return err
+	}
+	return nil
+}

internal/kubeconfig/namespace_test.go

@@ -0,0 +1,94 @@
+// Copyright 2021 Google LLC
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//      http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+package kubeconfig
+
+import (
+	"testing"
+
+	"github.com/google/go-cmp/cmp"
+
+	"github.com/ahmetb/kubectx/internal/testutil"
+)
+
+func TestKubeconfig_NamespaceOfContext_ctxNotFound(t *testing.T) {
+	kc := new(Kubeconfig).WithLoader(WithMockKubeconfigLoader(testutil.KC().
+		WithCtxs(testutil.Ctx("c1")).ToYAML(t)))
+	if err := kc.Parse(); err != nil {
+		t.Fatal(err)
+	}
+
+	_, err := kc.NamespaceOfContext("c2")
+	if err == nil {
+		t.Fatal("expected err")
+	}
+}
+
+func TestKubeconfig_NamespaceOfContext(t *testing.T) {
+	kc := new(Kubeconfig).WithLoader(WithMockKubeconfigLoader(testutil.KC().
+		WithCtxs(
+			testutil.Ctx("c1"),
+			testutil.Ctx("c2").Ns("c2n1")).ToYAML(t)))
+	if err := kc.Parse(); err != nil {
+		t.Fatal(err)
+	}
+
+	v1, err := kc.NamespaceOfContext("c1")
+	if err != nil {
+		t.Fatal("expected err")
+	}
+	if expected := `default`; v1 != expected {
+		t.Fatalf("c1: expected=\"%s\" got=\"%s\"", expected, v1)
+	}
+
+	v2, err := kc.NamespaceOfContext("c2")
+	if err != nil {
+		t.Fatal("expected err")
+	}
+	if expected := `c2n1`; v2 != expected {
+		t.Fatalf("c2: expected=\"%s\" got=\"%s\"", expected, v2)
+	}
+}
+
+func TestKubeconfig_SetNamespace(t *testing.T) {
+	l := WithMockKubeconfigLoader(testutil.KC().
+		WithCtxs(
+			testutil.Ctx("c1"),
+			testutil.Ctx("c2").Ns("c2n1")).ToYAML(t))
+	kc := new(Kubeconfig).WithLoader(l)
+	if err := kc.Parse(); err != nil {
+		t.Fatal(err)
+	}
+
+	if err := kc.SetNamespace("c3", "foo"); err == nil {
+		t.Fatalf("expected error for non-existing ctx")
+	}
+
+	if err := kc.SetNamespace("c1", "c1n1"); err != nil {
+		t.Fatal(err)
+	}
+	if err := kc.SetNamespace("c2", "c2n2"); err != nil {
+		t.Fatal(err)
+	}
+	if err := kc.Save(); err != nil {
+		t.Fatal(err)
+	}
+
+	expected := testutil.KC().WithCtxs(
+		testutil.Ctx("c1").Ns("c1n1"),
+		testutil.Ctx("c2").Ns("c2n2")).ToYAML(t)
+	if diff := cmp.Diff(l.Output(), expected); diff != "" {
+		t.Fatal(diff)
+	}
+}

internal/printer/color.go

@@ -0,0 +1,54 @@
+// Copyright 2021 Google LLC
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//      http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+package printer
+
+import (
+	"os"
+
+	"github.com/fatih/color"
+
+	"github.com/ahmetb/kubectx/internal/env"
+)
+
+var (
+	ActiveItemColor = color.New(color.FgGreen, color.Bold)
+)
+
+func init() {
+	EnableOrDisableColor(ActiveItemColor)
+}
+
+// useColors returns true if colors are force-enabled,
+// false if colors are disabled, or nil for default behavior
+// which is determined based on factors like if stdout is tty.
+func useColors() *bool {
+	tr, fa := true, false
+	if os.Getenv(env.EnvForceColor) != "" {
+		return &tr
+	} else if os.Getenv(env.EnvNoColor) != "" {
+		return &fa
+	}
+	return nil
+}
+
+// EnableOrDisableColor determines if color should be force-enabled or force-disabled
+// or left untouched based on environment configuration.
+func EnableOrDisableColor(c *color.Color) {
+	if v := useColors(); v != nil && *v {
+		c.EnableColor()
+	} else if v != nil && !*v {
+		c.DisableColor()
+	}
+}

internal/printer/color_test.go

@@ -0,0 +1,53 @@
+// Copyright 2021 Google LLC
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//      http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+package printer
+
+import (
+	"testing"
+
+	"github.com/google/go-cmp/cmp"
+
+	"github.com/ahmetb/kubectx/internal/testutil"
+)
+
+var (
+	tr, fa = true, false
+)
+
+func Test_useColors_forceColors(t *testing.T) {
+	defer testutil.WithEnvVar("_KUBECTX_FORCE_COLOR", "1")()
+	defer testutil.WithEnvVar("NO_COLOR", "1")()
+
+	if v := useColors(); !cmp.Equal(v, &tr) {
+		t.Fatalf("expected useColors() = true; got = %v", v)
+	}
+}
+
+func Test_useColors_disableColors(t *testing.T) {
+	defer testutil.WithEnvVar("NO_COLOR", "1")()
+
+	if v := useColors(); !cmp.Equal(v, &fa) {
+		t.Fatalf("expected useColors() = false; got = %v", v)
+	}
+}
+
+func Test_useColors_default(t *testing.T) {
+	defer testutil.WithEnvVar("NO_COLOR", "")()
+	defer testutil.WithEnvVar("_KUBECTX_FORCE_COLOR", "")()
+
+	if v := useColors(); v != nil {
+		t.Fatalf("expected useColors() = nil; got=%v", *v)
+	}
+}

internal/printer/printer.go

@@ -0,0 +1,59 @@
+// Copyright 2021 Google LLC
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//      http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+package printer
+
+import (
+	"fmt"
+	"io"
+
+	"github.com/fatih/color"
+)
+
+var (
+	ErrorColor   = color.New(color.FgRed, color.Bold)
+	WarningColor = color.New(color.FgYellow, color.Bold)
+	SuccessColor = color.New(color.FgGreen)
+)
+
+func init() {
+	colors := useColors()
+	if colors == nil {
+		return
+	}
+	if *colors {
+		ErrorColor.EnableColor()
+		WarningColor.EnableColor()
+		SuccessColor.EnableColor()
+	} else {
+		ErrorColor.DisableColor()
+		WarningColor.DisableColor()
+		SuccessColor.DisableColor()
+	}
+}
+
+func Error(w io.Writer, format string, args ...interface{}) error {
+	_, err := fmt.Fprintf(w, ErrorColor.Sprint("error: ")+format+"\n", args...)
+	return err
+}
+
+func Warning(w io.Writer, format string, args ...interface{}) error {
+	_, err := fmt.Fprintf(w, WarningColor.Sprint("warning: ")+format+"\n", args...)
+	return err
+}
+
+func Success(w io.Writer, format string, args ...interface{}) error {
+	_, err := fmt.Fprintf(w, SuccessColor.Sprint("✔ ")+fmt.Sprintf(format+"\n", args...))
+	return err
+}

internal/testutil/kubeconfigbuilder.go

@@ -0,0 +1,55 @@
+// Copyright 2021 Google LLC
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//      http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+package testutil
+
+import (
+	"strings"
+	"testing"
+
+	"sigs.k8s.io/kustomize/kyaml/yaml"
+)
+
+type Context struct {
+	Name    string `yaml:"name,omitempty"`
+	Context struct {
+		Namespace string `yaml:"namespace,omitempty"`
+	} `yaml:"context,omitempty"`
+}
+
+func Ctx(name string) *Context           { return &Context{Name: name} }
+func (c *Context) Ns(ns string) *Context { c.Context.Namespace = ns; return c }
+
+type Kubeconfig map[string]interface{}
+
+func KC() *Kubeconfig {
+	return &Kubeconfig{
+		"apiVersion": "v1",
+		"kind":       "Config"}
+}
+
+func (k *Kubeconfig) Set(key string, v interface{}) *Kubeconfig { (*k)[key] = v; return k }
+func (k *Kubeconfig) WithCurrentCtx(s string) *Kubeconfig       { (*k)["current-context"] = s; return k }
+func (k *Kubeconfig) WithCtxs(c ...*Context) *Kubeconfig        { (*k)["contexts"] = c; return k }
+
+func (k *Kubeconfig) ToYAML(t *testing.T) string {
+	t.Helper()
+	var v strings.Builder
+	enc := yaml.NewEncoder(&v)
+	enc.SetIndent(0)
+	if err := enc.Encode(*k); err != nil {
+		t.Fatalf("failed to encode mock kubeconfig: %v", err)
+	}
+	return v.String()
+}

internal/testutil/tempfile.go

@@ -0,0 +1,40 @@
+// Copyright 2021 Google LLC
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//      http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+package testutil
+
+import (
+	"io/ioutil"
+	"os"
+	"testing"
+)
+
+func TempFile(t *testing.T, contents string) (path string, cleanup func()) {
+	// TODO consider removing, used only in one place.
+	t.Helper()
+
+	f, err := ioutil.TempFile(os.TempDir(), "test-file")
+	if err != nil {
+		t.Fatalf("failed to create test file: %v", err)
+	}
+	path = f.Name()
+	if _, err := f.Write([]byte(contents)); err != nil {
+		t.Fatalf("failed to write to test file: %v", err)
+	}
+
+	return path, func() {
+		f.Close()
+		os.Remove(path)
+	}
+}

internal/testutil/testutil.go

@@ -0,0 +1,31 @@
+// Copyright 2021 Google LLC
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//      http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+package testutil
+
+import "os"
+
+// WithEnvVar sets an env var temporarily. Call its return value
+// in defer to restore original value in env (if exists).
+func WithEnvVar(key, value string) func() {
+	orig, ok := os.LookupEnv(key)
+	os.Setenv(key, value)
+	return func() {
+		if ok {
+			os.Setenv(key, orig)
+		} else {
+			os.Unsetenv(key)
+		}
+	}
+}

kubectx

@@ -21,50 +21,75 @@
 set -eou pipefail
 IFS=$'\n\t'
 
-KUBECTX="${HOME}/.kube/kubectx"
+SELF_CMD="$0"
+
+KUBECTX="${XDG_CACHE_HOME:-$HOME/.kube}/kubectx"
 
 usage() {
-  cat <<"EOF"
+  local SELF
+  SELF="kubectx"
+  if [[ "$(basename "$0")" == kubectl-* ]]; then # invoked as plugin
+    SELF="kubectl ctx"
+  fi
+
+  cat <<EOF
+Manage and switch between kubectl contexts.
+
 USAGE:
-  kubectx                       : list the contexts
-  kubectx <NAME>                : switch to context <NAME>
-  kubectx -                     : switch to the previous context
-  kubectx <NEW_NAME>=<NAME>     : rename context <NAME> to <NEW_NAME>
-  kubectx <NEW_NAME>=.          : rename current-context to <NEW_NAME>
-  kubectx -d <NAME> [<NAME...>] : delete context <NAME> ('.' for current-context)
+  $SELF                       : list the contexts
+  $SELF <NAME>                : switch to context <NAME>
+  $SELF -                     : switch to the previous context
+  $SELF -c, --current         : show the current context name
+  $SELF <NEW_NAME>=<NAME>     : rename context <NAME> to <NEW_NAME>
+  $SELF <NEW_NAME>=.          : rename current-context to <NEW_NAME>
+  $SELF -d <NAME> [<NAME...>] : delete context <NAME> ('.' for current-context)
                                   (this command won't delete the user/cluster entry
                                   that is used by the context)
+  $SELF -u, --unset           : unset the current context
 
-  kubectx -h,--help         : show this message
+  $SELF -h,--help             : show this message
+
+  (This executable is the legacy bash-based implementation, consider upgrading to Go-based implementation.)
 EOF
-  exit 1
+}
+
+exit_err() {
+   echo >&2 "${1}"
+   exit 1
 }
 
 current_context() {
-  kubectl config view -o=jsonpath='{.current-context}'
+  $KUBECTL config view -o=jsonpath='{.current-context}'
 }
 
 get_contexts() {
-  kubectl config get-contexts -o=name | sort -n
+  $KUBECTL config get-contexts -o=name | sort -n
 }
 
 list_contexts() {
   set -u pipefail
-  local cur
-  cur="$(current_context)"
+  local cur ctx_list
+  cur="$(current_context)" || exit_err "error getting current context"
+  ctx_list=$(get_contexts) || exit_err "error getting context list"
 
   local yellow darkbg normal
-  yellow=$(tput setaf 3)
-  darkbg=$(tput setab 0)
-  normal=$(tput sgr0)
+  yellow=$(tput setaf 3 || true)
+  darkbg=$(tput setab 0 || true)
+  normal=$(tput sgr0 || true)
 
   local cur_ctx_fg cur_ctx_bg
   cur_ctx_fg=${KUBECTX_CURRENT_FGCOLOR:-$yellow}
   cur_ctx_bg=${KUBECTX_CURRENT_BGCOLOR:-$darkbg}
 
-  for c in $(get_contexts); do
-  if [[ -t 1 && -z "${NO_COLOR:-}" && "${c}" = "${cur}" ]]; then
-    echo "${cur_ctx_bg}${cur_ctx_fg}${c}${normal}"
+  for c in $ctx_list; do
+  if [[ -n "${_KUBECTX_FORCE_COLOR:-}" || \
+       -t 1 && -z "${NO_COLOR:-}" ]]; then
+    # colored output mode
+    if [[ "${c}" = "${cur}" ]]; then
+      echo "${cur_ctx_bg}${cur_ctx_fg}${c}${normal}"
+    else
+      echo "${c}"
+    fi
   else
     echo "${c}"
   fi
@@ -87,12 +112,25 @@ save_context() {
 }
 
 switch_context() {
-  kubectl config use-context "${1}"
+  $KUBECTL config use-context "${1}"
+}
+
+choose_context_interactive() {
+  local choice
+  choice="$(_KUBECTX_FORCE_COLOR=1 \
+    FZF_DEFAULT_COMMAND="${SELF_CMD}" \
+    fzf --ansi --no-preview || true)"
+  if [[ -z "${choice}" ]]; then
+    echo 2>&1 "error: you did not choose any of the options"
+    exit 1
+  else
+    set_context "${choice}"
+  fi
 }
 
 set_context() {
   local prev
-  prev="$(current_context)"
+  prev="$(current_context)" || exit_err "error getting current context"
 
   switch_context "${1}"
 
@@ -111,20 +149,8 @@ swap_context() {
   set_context "${ctx}"
 }
 
-user_of_context() {
-  # TODO(ahmetb) no longer used, consider deleting
-  kubectl config view \
-    -o=jsonpath="{.contexts[?(@.name==\"${1}\")].context.user}"
-}
-
-cluster_of_context() {
-  # TODO(ahmetb) no longer used, consider deleting
-  kubectl config view \
-    -o=jsonpath="{.contexts[?(@.name==\"${1}\")].context.cluster}"
-}
-
 context_exists() {
-  grep -q ^"${1}"\$ <(kubectl config get-contexts -o=name)
+  grep -q ^"${1}"\$ <($KUBECTL config get-contexts -o=name)
 }
 
 rename_context() {
@@ -135,26 +161,21 @@ rename_context() {
     old_name="$(current_context)"
   fi
 
-  # TODO(ahmetb) old_user and old_cluster are no longer used, clean up
-  local old_user old_cluster
-  old_user="$(user_of_context "${old_name}")"
-  old_cluster="$(cluster_of_context "${old_name}")"
-  if [[ -z "$old_user" || -z "$old_cluster" ]]; then
-    echo "error: Cannot retrieve context ${old_name}."  >&2
+  if ! context_exists "${old_name}"; then
+    echo "error: Context \"${old_name}\" not found, can't rename it." >&2
     exit 1
   fi
 
   if context_exists "${new_name}"; then
     echo "Context \"${new_name}\" exists, deleting..." >&2
-    kubectl config delete-context "${new_name}" 1>/dev/null 2>&1
+    $KUBECTL config delete-context "${new_name}" 1>/dev/null 2>&1
   fi
 
-  kubectl config rename-context "${old_name}" "${new_name}"
+  $KUBECTL config rename-context "${old_name}" "${new_name}"
 }
 
 delete_contexts() {
-  IFS=' ' read -ra CTXS <<< "${1}"
-  for i in "${CTXS[@]}"; do
+  for i in "${@}"; do
     delete_context "${i}"
   done
 }
@@ -163,32 +184,62 @@ delete_context() {
   local ctx
   ctx="${1}"
   if [[ "${ctx}" == "." ]]; then
-    ctx="$(current_context)"
+    ctx="$(current_context)" || exit_err "error getting current context"
   fi
   echo "Deleting context \"${ctx}\"..." >&2
-  kubectl config delete-context "${ctx}"
+  $KUBECTL config delete-context "${ctx}"
+}
+
+unset_context() {
+  echo "Unsetting current context." >&2
+  $KUBECTL config unset current-context
 }
 
 main() {
+  if [[ -z "${KUBECTL:-}" ]]; then
+    if hash kubectl 2>/dev/null; then
+      KUBECTL=kubectl
+    elif hash kubectl.exe  2>/dev/null; then
+      KUBECTL=kubectl.exe
+    else
+      echo >&2 "kubectl is not installed"
+      exit 1
+    fi
+  fi
+
   if [[ "$#" -eq 0 ]]; then
-    list_contexts
+    if [[ -t 1 &&  -z "${KUBECTX_IGNORE_FZF:-}" && "$(type fzf &>/dev/null; echo $?)" -eq 0 ]]; then
+      choose_context_interactive
+    else
+      list_contexts
+    fi
   elif [[ "${1}" == "-d" ]]; then
     if [[ "$#" -lt 2 ]]; then
       echo "error: missing context NAME" >&2
       usage
+      exit 1
     fi
     delete_contexts "${@:2}"
   elif [[ "$#" -gt 1 ]]; then
     echo "error: too many arguments" >&2
     usage
+    exit 1
   elif [[ "$#" -eq 1 ]]; then
     if [[ "${1}" == "-" ]]; then
       swap_context
+    elif [[ "${1}" == '-c' || "${1}" == '--current' ]]; then
+      # we don't call current_context here for two reasons:
+      # - it does not fail when current-context property is not set
+      # - it does not return a trailing newline
+      $KUBECTL config current-context
+    elif [[ "${1}" == '-u' || "${1}" == '--unset' ]]; then
+      unset_context
     elif [[ "${1}" == '-h' || "${1}" == '--help' ]]; then
       usage
     elif [[ "${1}" =~ ^-(.*) ]]; then
       echo "error: unrecognized flag \"${1}\"" >&2
       usage
+      exit 1
     elif [[ "${1}" =~ (.+)=(.+) ]]; then
       rename_context "${BASH_REMATCH[2]}" "${BASH_REMATCH[1]}"
     else
@@ -196,6 +247,7 @@ main() {
     fi
   else
     usage
+    exit 1
   fi
 }
 

kubens

@@ -1,6 +1,6 @@
 #!/usr/bin/env bash
 #
-# kubenx(1) is a utility to switch between Kubernetes namespaces.
+# kubens(1) is a utility to switch between Kubernetes namespaces.
 
 # Copyright 2017 Google Inc.
 #
@@ -21,23 +21,43 @@
 set -eou pipefail
 IFS=$'\n\t'
 
-KUBENS_DIR="${HOME}/.kube/kubens"
+SELF_CMD="$0"
+
+KUBENS_DIR="${XDG_CACHE_HOME:-$HOME/.kube}/kubens"
 
 usage() {
-  cat <<"EOF"
+  local SELF
+  SELF="kubens"
+  if [[ "$(basename "$0")" == kubectl-* ]]; then # invoked as plugin
+    SELF="kubectl ns"
+  fi
+
+  cat <<EOF
+Switch between Kubernetes namespaces.
+
 USAGE:
-  kubens                    : list the namespaces in the current context
-  kubens <NAME>             : change the active namespace of current context
-  kubens -                  : switch to the previous namespace in this context
-  kubens -h,--help          : show this message
+  $SELF                    : list the namespaces in the current context
+  $SELF <NAME>             : change the active namespace of current context
+  $SELF -                  : switch to the previous namespace in this context
+  $SELF -c, --current      : show the current namespace
+  $SELF -h,--help          : show this message
+
+  (This executable is the legacy bash-based implementation, consider upgrading to Go-based implementation.)
 EOF
-  exit 1
+}
+
+exit_err() {
+   echo >&2 "${1}"
+   exit 1
 }
 
 current_namespace() {
   local cur_ctx
-  cur_ctx="$(current_context)"
-  ns="$(kubectl config view -o=jsonpath="{.contexts[?(@.name==\"${cur_ctx}\")].context.namespace}")"
+
+  cur_ctx="$(current_context)" || exit_err "error getting current context"
+  ns="$($KUBECTL config view -o=jsonpath="{.contexts[?(@.name==\"${cur_ctx}\")].context.namespace}")" \
+     || exit_err "error getting current namespace"
+
   if [[ -z "${ns}" ]]; then
     echo "default"
   else
@@ -46,11 +66,11 @@ current_namespace() {
 }
 
 current_context() {
-  kubectl config view -o=jsonpath='{.current-context}'
+  $KUBECTL config current-context
 }
 
 get_namespaces() {
-  kubectl get namespaces -o=jsonpath='{range .items[*].metadata.name}{@}{"\n"}{end}'
+  $KUBECTL get namespaces -o=jsonpath='{range .items[*].metadata.name}{@}{"\n"}{end}'
 }
 
 escape_context_name() {
@@ -58,7 +78,9 @@ escape_context_name() {
 }
 
 namespace_file() {
-  local ctx="$(escape_context_name "${1}")"
+  local ctx
+
+  ctx="$(escape_context_name "${1}")"
   echo "${KUBENS_DIR}/${ctx}"
 }
 
@@ -82,14 +104,35 @@ save_namespace() {
 
 switch_namespace() {
   local ctx="${1}"
-  kubectl config set-context "${ctx}" --namespace="${2}"
+  $KUBECTL config set-context "${ctx}" --namespace="${2}"
   echo "Active namespace is \"${2}\".">&2
 }
 
+choose_namespace_interactive() {
+  # directly calling kubens via fzf might fail with a cryptic error like
+  # "$FZF_DEFAULT_COMMAND failed", so try to see if we can list namespaces
+  # locally first
+  if [[ -z "$(list_namespaces)" ]]; then
+    echo >&2 "error: could not list namespaces (is the cluster accessible?)"
+    exit 1
+  fi
+
+  local choice
+  choice="$(_KUBECTX_FORCE_COLOR=1 \
+    FZF_DEFAULT_COMMAND="${SELF_CMD}" \
+    fzf --ansi --no-preview || true)"
+  if [[ -z "${choice}" ]]; then
+    echo 2>&1 "error: you did not choose any of the options"
+    exit 1
+  else
+    set_namespace "${choice}"
+  fi
+}
+
 set_namespace() {
   local ctx prev
-  ctx="$(current_context)"
-  prev="$(current_namespace)"
+  ctx="$(current_context)" || exit_err "error getting current context"
+  prev="$(current_namespace)" || exit_error "error getting current namespace"
 
   if grep -q ^"${1}"\$ <(get_namespaces); then
     switch_namespace "${ctx}" "${1}"
@@ -105,29 +148,36 @@ set_namespace() {
 
 list_namespaces() {
   local yellow darkbg normal
-  yellow=$(tput setaf 3)
-  darkbg=$(tput setab 0)
-  normal=$(tput sgr0)
+  yellow=$(tput setaf 3 || true)
+  darkbg=$(tput setab 0 || true)
+  normal=$(tput sgr0 || true)
 
   local cur_ctx_fg cur_ctx_bg
   cur_ctx_fg=${KUBECTX_CURRENT_FGCOLOR:-$yellow}
   cur_ctx_bg=${KUBECTX_CURRENT_BGCOLOR:-$darkbg}
 
   local cur ns_list
-  cur="$(current_namespace)"
-  ns_list=$(get_namespaces)
+  cur="$(current_namespace)" || exit_err "error getting current namespace"
+  ns_list=$(get_namespaces) || exit_err "error getting namespace list"
+
   for c in $ns_list; do
-    if [[ -t 1 && -z "${NO_COLOR:-}" && "${c}" = "${cur}" ]]; then
+  if [[ -n "${_KUBECTX_FORCE_COLOR:-}" || \
+       -t 1 && -z "${NO_COLOR:-}" ]]; then
+    # colored output mode
+    if [[ "${c}" = "${cur}" ]]; then
       echo "${cur_ctx_bg}${cur_ctx_fg}${c}${normal}"
     else
       echo "${c}"
     fi
+  else
+    echo "${c}"
+  fi
   done
 }
 
 swap_namespace() {
   local ctx ns
-  ctx="$(current_context)"
+  ctx="$(current_context)" || exit_err "error getting current context"
   ns="$(read_namespace "${ctx}")"
   if [[ -z "${ns}" ]]; then
     echo "error: No previous namespace found for current context." >&2
@@ -137,16 +187,34 @@ swap_namespace() {
 }
 
 main() {
+  if [[ -z "${KUBECTL:-}" ]]; then
+    if hash kubectl 2>/dev/null; then
+      KUBECTL=kubectl
+    elif hash kubectl.exe  2>/dev/null; then
+      KUBECTL=kubectl.exe
+    else
+      echo >&2 "kubectl is not installed"
+      exit 1
+    fi
+  fi
+
   if [[ "$#" -eq 0 ]]; then
-    list_namespaces
+    if [[ -t 1 && -z ${KUBECTX_IGNORE_FZF:-} && "$(type fzf &>/dev/null; echo $?)" -eq 0 ]]; then
+      choose_namespace_interactive
+    else
+      list_namespaces
+    fi
   elif [[ "$#" -eq 1 ]]; then
     if [[ "${1}" == '-h' || "${1}" == '--help' ]]; then
       usage
     elif [[ "${1}" == "-" ]]; then
       swap_namespace
+    elif [[ "${1}" == '-c' || "${1}" == '--current' ]]; then
+      current_namespace
     elif [[ "${1}" =~ ^-(.*) ]]; then
       echo "error: unrecognized flag \"${1}\"" >&2
       usage
+      exit 1
     elif [[ "${1}" =~ (.+)=(.+) ]]; then
       alias_context "${BASH_REMATCH[2]}" "${BASH_REMATCH[1]}"
     else
@@ -155,6 +223,7 @@ main() {
   else
     echo "error: too many flags" >&2
     usage
+    exit 1
   fi
 }
 

test/common.bash

@@ -0,0 +1,32 @@
+#!/usr/bin/env bats
+
+# bats setup function
+setup() {
+  TEMP_HOME="$(mktemp -d)"
+  export TEMP_HOME
+  export HOME=$TEMP_HOME
+  export KUBECONFIG="${TEMP_HOME}/config"
+}
+
+# bats teardown function
+teardown() {
+  rm -rf "$TEMP_HOME"
+}
+
+use_config() {
+  cp "$BATS_TEST_DIRNAME/testdata/$1" $KUBECONFIG
+}
+
+# wrappers around "kubectl config" command
+
+get_namespace() {
+  kubectl config view -o=jsonpath="{.contexts[?(@.name==\"$(get_context)\")].context.namespace}"
+}
+
+get_context() {
+  kubectl config current-context
+}
+
+switch_context() {
+  kubectl config use-context "${1}"
+}

test/kubectx.bats

@@ -0,0 +1,244 @@
+#!/usr/bin/env bats
+
+COMMAND="${COMMAND:-$BATS_TEST_DIRNAME/../kubectx}"
+
+load common
+
+@test "--help should not fail" {
+  run ${COMMAND} --help
+  echo "$output"
+  [ "$status" -eq 0 ]
+}
+
+@test "-h should not fail" {
+  run ${COMMAND} -h
+  echo "$output"
+  [ "$status" -eq 0 ]
+}
+
+@test "switch to previous context when no one exists" {
+  use_config config1
+
+  run ${COMMAND} -
+  echo "$output"
+  [ "$status" -eq 1 ]
+  [[ $output = *"no previous context found" ]]
+}
+
+@test "list contexts when no kubeconfig exists" {
+  run ${COMMAND}
+  echo "$output"
+  [ "$status" -eq 0 ]
+  [[ "$output" = "warning: kubeconfig file not found" ]]
+}
+
+@test "get one context and list contexts" {
+  use_config config1
+
+  run ${COMMAND}
+  echo "$output"
+  [ "$status" -eq 0 ]
+  [[ "$output" = "user1@cluster1" ]]
+}
+
+@test "get two contexts and list contexts" {
+  use_config config2
+
+  run ${COMMAND}
+  echo "$output"
+  [ "$status" -eq 0 ]
+  [[ "$output" = *"user1@cluster1"* ]]
+  [[ "$output" = *"user2@cluster1"* ]]
+}
+
+@test "get two contexts and select contexts" {
+  use_config config2
+
+  run ${COMMAND} user1@cluster1
+  echo "$output"
+  [ "$status" -eq 0 ]
+  echo "$(get_context)"
+  [[ "$(get_context)" = "user1@cluster1" ]]
+
+  run ${COMMAND} user2@cluster1
+  echo "$output"
+  [ "$status" -eq 0 ]
+  echo "$(get_context)"
+  [[ "$(get_context)" = "user2@cluster1" ]]
+}
+
+@test "get two contexts and switch between contexts" {
+  use_config config2
+
+  run ${COMMAND} user1@cluster1
+  echo "$output"
+  [ "$status" -eq 0 ]
+  echo "$(get_context)"
+  [[ "$(get_context)" = "user1@cluster1" ]]
+
+  run ${COMMAND} user2@cluster1
+  echo "$output"
+  [ "$status" -eq 0 ]
+  echo "$(get_context)"
+  [[ "$(get_context)" = "user2@cluster1" ]]
+
+  run ${COMMAND} -
+  echo "$output"
+  [ "$status" -eq 0 ]
+  echo "$(get_context)"
+  [[ "$(get_context)" = "user1@cluster1" ]]
+
+  run ${COMMAND} -
+  echo "$output"
+  [ "$status" -eq 0 ]
+  echo "$(get_context)"
+  [[ "$(get_context)" = "user2@cluster1" ]]
+}
+
+@test "get one context and switch to non existent context" {
+  use_config config1
+
+  run ${COMMAND} "unknown-context"
+  echo "$output"
+  [ "$status" -eq 1 ]
+}
+
+@test "-c/--current fails when no context set" {
+  use_config config1
+
+  run "${COMMAND}" -c
+  echo "$output"
+  [ $status -eq 1 ]
+  run "${COMMAND}" --current
+  echo "$output"
+  [ $status -eq 1 ]
+}
+
+@test "-c/--current prints the current context" {
+  use_config config1
+
+  run "${COMMAND}" user1@cluster1
+  [ $status -eq 0 ]
+
+  run "${COMMAND}" -c
+  echo "$output"
+  [ $status -eq 0 ]
+  [[ "$output" = "user1@cluster1" ]]
+  run "${COMMAND}" --current
+  echo "$output"
+  [ $status -eq 0 ]
+  [[ "$output" = "user1@cluster1" ]]
+}
+
+@test "rename context" {
+  use_config config2
+
+  run ${COMMAND} "new-context=user1@cluster1"
+  echo "$output"
+  [ "$status" -eq 0 ]
+
+  run ${COMMAND}
+  echo "$output"
+  [ "$status" -eq 0 ]
+  [[ ! "$output" = *"user1@cluster1"* ]]
+  [[ "$output" = *"new-context"* ]]
+  [[ "$output" = *"user2@cluster1"* ]]
+}
+
+@test "rename current context" {
+  use_config config2
+
+  run ${COMMAND} user2@cluster1
+  echo "$output"
+  [ "$status" -eq 0 ]
+
+  run ${COMMAND} new-context=.
+  echo "$output"
+  [ "$status" -eq 0 ]
+
+  run ${COMMAND}
+  echo "$output"
+  [ "$status" -eq 0 ]
+  [[ ! "$output" = *"user2@cluster1"* ]]
+  [[ "$output" = *"user1@cluster1"* ]]
+  [[ "$output" = *"new-context"* ]]
+}
+
+@test "delete context" {
+  use_config config2
+
+  run ${COMMAND} -d "user1@cluster1"
+  echo "$output"
+  [ "$status" -eq 0 ]
+
+  run ${COMMAND}
+  echo "$output"
+  [ "$status" -eq 0 ]
+  [[ ! "$output" = "user1@cluster1" ]]
+  [[ "$output" = "user2@cluster1" ]]
+}
+
+@test "delete current context" {
+  use_config config2
+
+  run ${COMMAND} user2@cluster1
+  echo "$output"
+  [ "$status" -eq 0 ]
+
+  run ${COMMAND} -d .
+  echo "$output"
+  [ "$status" -eq 0 ]
+
+  run ${COMMAND}
+  echo "$output"
+  [ "$status" -eq 0 ]
+  [[ ! "$output" = "user2@cluster1" ]]
+  [[ "$output" = "user1@cluster1" ]]
+}
+
+@test "delete non existent context" {
+  use_config config1
+
+  run ${COMMAND} -d "unknown-context"
+  echo "$output"
+  [ "$status" -eq 1 ]
+}
+
+@test "delete several contexts" {
+  use_config config2
+
+  run ${COMMAND} -d "user1@cluster1" "user2@cluster1"
+  echo "$output"
+  [ "$status" -eq 0 ]
+
+  run ${COMMAND}
+  echo "$output"
+  [ "$status" -eq 0 ]
+  [[ "$output" = "" ]]
+}
+
+@test "delete several contexts including a non existent one" {
+  use_config config2
+
+  run ${COMMAND} -d "user1@cluster1" "non-existent" "user2@cluster1"
+  echo "$output"
+  [ "$status" -eq 1 ]
+
+  run ${COMMAND}
+  echo "$output"
+  [ "$status" -eq 0 ]
+  [[ "$output" = "user2@cluster1" ]]
+}
+
+@test "unset selected context" {
+  use_config config2
+
+  run ${COMMAND} user1@cluster1
+  [ "$status" -eq 0 ]
+
+  run ${COMMAND} -u
+  [ "$status" -eq 0 ]
+
+  run ${COMMAND} -c
+  [ "$status" -ne 0 ]
+}

test/kubens.bats

@@ -0,0 +1,148 @@
+#!/usr/bin/env bats
+
+COMMAND="${COMMAND:-$BATS_TEST_DIRNAME/../kubens}"
+
+# TODO(ahmetb) remove this after bash implementations are deleted
+export KUBECTL="$BATS_TEST_DIRNAME/../test/mock-kubectl"
+
+# short-circuit namespace querying in kubens go implementation
+export _MOCK_NAMESPACES=1
+
+load common
+
+@test "--help should not fail" {
+  run ${COMMAND} --help
+  echo "$output">&2
+  [[ "$status" -eq 0 ]]
+}
+
+@test "-h should not fail" {
+  run ${COMMAND} -h
+  echo "$output">&2
+  [[ "$status" -eq 0 ]]
+}
+
+@test "list namespaces when no kubeconfig exists" {
+  run ${COMMAND}
+  echo "$output"
+  [[ "$status" -eq 1 ]]
+}
+
+@test "list namespaces" {
+  use_config config1
+  switch_context user1@cluster1
+
+  run ${COMMAND}
+  echo "$output"
+  [[ "$status" -eq 0 ]]
+  [[ "$output" = *"ns1"* ]]
+  [[ "$output" = *"ns2"* ]]
+}
+
+@test "switch to existing namespace" {
+  use_config config1
+  switch_context user1@cluster1
+
+  run ${COMMAND} "ns1"
+  echo "$output"
+  [[ "$status" -eq 0 ]]
+  [[ "$output" = *'Active namespace is "ns1"'* ]]
+}
+
+@test "switch to non-existing namespace" {
+  use_config config1
+  switch_context user1@cluster1
+
+  run ${COMMAND} "unknown-namespace"
+  echo "$output"
+  [[ "$status" -eq 1 ]]
+  [[ "$output" = *'no namespace exists with name "unknown-namespace"'* ]]
+}
+
+@test "switch between namespaces" {
+  use_config config1
+  switch_context user1@cluster1
+
+  run ${COMMAND} ns1
+  echo "$output"
+  [[ "$status" -eq 0 ]]
+  echo "$(get_namespace)"
+  [[ "$(get_namespace)" = "ns1" ]]
+
+  run ${COMMAND} ns2
+  echo "$output"
+  [[ "$status" -eq 0 ]]
+  echo "$(get_namespace)"
+  [[ "$(get_namespace)" = "ns2" ]]
+
+  run ${COMMAND} -
+  echo "$output"
+  [[ "$status" -eq 0 ]]
+  echo "$(get_namespace)"
+  [[ "$(get_namespace)" = "ns1" ]]
+
+  run ${COMMAND} -
+  echo "$output"
+  [[ "$status" -eq 0 ]]
+  echo "$(get_namespace)"
+  [[ "$(get_namespace)" = "ns2" ]]
+}
+
+@test "switch to previous namespace when none exists" {
+  use_config config1
+  switch_context user1@cluster1
+
+  run ${COMMAND} -
+  echo "$output"
+  [[ "$status" -eq 1 ]]
+  [[ "$output" = *"No previous namespace found for current context"* ]]
+}
+
+@test "switch to namespace when current context is empty" {
+  use_config config1
+
+  run ${COMMAND} -
+  echo "$output"
+  [[ "$status" -eq 1 ]]
+  [[ "$output" = *"current-context is not set"* ]]
+}
+
+@test "-c/--current works when no namespace is set on context" {
+  use_config config1
+  switch_context user1@cluster1
+
+  run ${COMMAND} "-c"
+  echo "$output"
+  [[ "$status" -eq 0 ]]
+  [[ "$output" = "default" ]]
+  run ${COMMAND} "--current"
+  echo "$output"
+  [[ "$status" -eq 0 ]]
+  [[ "$output" = "default" ]]
+}
+
+@test "-c/--current prints the namespace after it is set" {
+  use_config config1
+  switch_context user1@cluster1
+  ${COMMAND} ns1
+
+  run ${COMMAND} "-c"
+  echo "$output"
+  [[ "$status" -eq 0 ]]
+  [[ "$output" = "ns1" ]]
+  run ${COMMAND} "--current"
+  echo "$output"
+  [[ "$status" -eq 0 ]]
+  [[ "$output" = "ns1" ]]
+}
+
+@test "-c/--current fails when current context is not set" {
+  use_config config1
+  run ${COMMAND} -c
+  echo "$output"
+  [[ "$status" -eq 1 ]]
+
+  run ${COMMAND} --current
+  echo "$output"
+  [[ "$status" -eq 1 ]]
+}

test/mock-kubectl

@@ -0,0 +1,12 @@
+#!/usr/bin/env bash
+
+[[ -n $DEBUG ]] && set -x
+
+set -eou pipefail
+
+if [[ $@ == *'get namespaces'* ]]; then
+  echo "ns1"
+  echo "ns2"
+else
+  kubectl $@
+fi

test/testdata/config1

@@ -0,0 +1,18 @@
+# config with one context
+
+apiVersion: v1
+clusters:
+- cluster:
+    server: ""
+  name: cluster1
+contexts:
+- context:
+    cluster: cluster1
+    user: user1
+  name: user1@cluster1
+current-context: ""
+kind: Config
+preferences: {}
+users:
+- name: user1
+  user: {}

test/testdata/config2

@@ -0,0 +1,24 @@
+# config with two contexts
+
+apiVersion: v1
+clusters:
+- cluster:
+    server: ""
+  name: cluster1
+contexts:
+- context:
+    cluster: cluster1
+    user: user1
+  name: user1@cluster1
+- context:
+    cluster: cluster1
+    user: user2
+  name: user2@cluster1
+current-context: ""
+kind: Config
+preferences: {}
+users:
+- name: user1
+  user: {}
+- name: user2
+  user: {}