fix: improve error handling and resource management in kubeconfig

This change addresses eight key improvements to the kubectx/kubens codebase:

Resource Management Fixes:
- Fix use-after-close bugs where Kubeconfig was accessed after Close()
- Fix resource leaks on error paths by ensuring defer kc.Close() is called
- Fix YAML encoder not being closed after Encode(), causing buffered data loss

API Design Improvements:
- Change ContextNames() to return ([]string, error) instead of silently returning
  nil on error, making parse failures distinguishable from empty results
- Change GetCurrentContext() to return (string, error) instead of returning ""
  for both "not set" and parse error cases
- Update all 16 call sites across cmd/kubectx and cmd/kubens packages to handle
  the new error returns while preserving backward-compatible behavior

Error Handling:
- Add explicit error handling for printer.Success() calls in 5+ locations
  by prefixing unchecked calls with _ =

Performance:
- Add slice pre-allocation in namespace list pagination using slices.Grow()
  before append loops, reducing allocations when fetching 500+ item batches

All changes maintain backward compatibility for missing kubeconfig keys while
improving error transparency and resource safety.

.github/workflows/release.yml

@@ -24,7 +24,7 @@ jobs:
     runs-on: ubuntu-latest
     steps:
     - name: Checkout
-      uses: actions/checkout@v4
+      uses: actions/checkout@master
     - run: git fetch --tags
     - name: Setup Go
       uses: actions/setup-go@v6

.goreleaser.yml

@@ -15,7 +15,7 @@
 # limitations under the License.
 
 # This is an example goreleaser.yaml file with some sane defaults.
-# Make sure to check the documentation at https://goreleaser.com
+# Make sure to check the documentation at http://goreleaser.com
 
 version: 2
 before:
@@ -69,11 +69,11 @@ archives:
       {{- else -}}v{{- . -}}
       {{- end -}}
     {{- end -}}
-  ids:
+  builds:
     - kubectx
   format_overrides:
     - goos: windows
-      formats: [zip]
+      format: zip
   files: ["LICENSE"]
 - id: kubens-archive
   name_template: |-
@@ -89,11 +89,11 @@ archives:
       {{- else -}}v{{- . -}}
       {{- end -}}
     {{- end -}}
-  ids:
+  builds:
     - kubens
   format_overrides:
     - goos: windows
-      formats: [zip]
+      format: zip
   files: ["LICENSE"]
 checksum:
   name_template: "checksums.txt"
@@ -111,7 +111,7 @@ snapcrafts:
       kubens is a tool to switch between Kubernetes namespaces (and configure them for kubectl) easily.
     grade: stable
     confinement: classic
-    base: core24
+    base: core20
     apps:
       kubectx:
         command: kubectx

README.md

@@ -72,23 +72,139 @@ names anymore.
 
 ## Installation
 
-| Package manager | Command |
-|---|---|
-| [Homebrew](https://brew.sh/) (macOS & Linux) | `brew install kubectx` |
-| [MacPorts](https://www.macports.org) (macOS) | `sudo port install kubectx` |
-| apt (Debian/Ubuntu) | `sudo apt install kubectx` |
-| pacman (Arch Linux) | `sudo pacman -S kubectx` |
-| [Chocolatey](https://chocolatey.org/) (Windows) | `choco install kubens kubectx` |
-| [Scoop](https://scoop.sh/) (Windows) | `scoop bucket add main && scoop install main/kubens main/kubectx` |
-| [winget](https://learn.microsoft.com/en-us/windows/package-manager/) (Windows) | `winget install --id ahmetb.kubectx && winget install --id ahmetb.kubens` |
-| [Krew](https://github.com/kubernetes-sigs/krew/) (kubectl plugin) | `kubectl krew install ctx && kubectl krew install ns` |
+Stable versions of `kubectx` and `kubens` are small bash scripts that you
+can find in this repository.
 
-Alternatively, download binaries from the [**Releases page →**](https://github.com/ahmetb/kubectx/releases) and add them to somewhere in your `PATH`.
+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
+→**](https://github.com/ahmetb/kubectx/releases)
 
-<details>
-<summary>Shell completion scripts</summary>
+**Installation options:**
 
-#### zsh (with [antibody](https://getantibody.github.io))
+- [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.
+
+
+### MacPorts (macOS)
+
+If you use [MacPorts](https://www.macports.org) you can install like this:
+
+```sh
+sudo port install kubectx
+```
+
+### 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.
+- Either:
+  - save them all to somewhere in your `PATH`,
+  - 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 ...`)
+
+Example installation steps:
+
+``` bash
+sudo git clone https://github.com/ahmetb/kubectx /opt/kubectx
+sudo ln -s /opt/kubectx/kubectx /usr/local/bin/kubectx
+sudo ln -s /opt/kubectx/kubens /usr/local/bin/kubens
+```
+
+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).
+
+#### Completion scripts for `zsh` with [antibody](https://getantibody.github.io)
 
 Add this line to your [Plugins File](https://getantibody.github.io/usage/) (e.g.
 `~/.zsh_plugins.txt`):
@@ -101,9 +217,9 @@ 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`.
+`compinit`. 
 
-#### zsh (plain)
+#### Completion scripts for plain `zsh`
 
 The completion scripts have to be in a path that belongs to `$fpath`. Either
 link or copy them to an existing folder.
@@ -128,7 +244,7 @@ depending on the `$fpath` of your zsh installation.
 
 In case of errors, calling `compaudit` might help.
 
-#### bash
+#### Completion scripts for `bash`
 
 ```bash
 git clone https://github.com/ahmetb/kubectx.git ~/.kubectx
@@ -143,7 +259,7 @@ export PATH=~/.kubectx:\$PATH
 EOF
 ```
 
-#### fish
+#### Completion scripts for `fish`
 
 ```fish
 mkdir -p ~/.config/fish/completions
@@ -151,12 +267,6 @@ ln -s /opt/kubectx/completion/kubectx.fish ~/.config/fish/completions/
 ln -s /opt/kubectx/completion/kubens.fish ~/.config/fish/completions/
 ```
 
-</details>
-
-> [!NOTE]
-> Tip: Show context/namespace in your shell prompt with [oh-my-posh](https://ohmyposh.dev/) or
-> simply with [kube-ps1](https://github.com/jonmosco/kube-ps1).
-
 -----
 
 ### Interactive mode
@@ -167,12 +277,12 @@ with fuzzy searching, you just need to [install
 
 ![kubectx interactive search with fzf](img/kubectx-interactive.gif)
 
-Caveats:
-- 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 `).
+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 `).
 
 -----
 
@@ -196,7 +306,7 @@ Colors in the output can be disabled by setting the
 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](https://github.com/jonmosco/kube-ps1).
+[kube-ps1].
 
 #### Stargazers over time
 

cmd/kubectx/fzf.go

@@ -52,14 +52,6 @@ func (op InteractiveSwitchOp) Run(_, stderr io.Writer) error {
 		return fmt.Errorf("kubeconfig error: %w", err)
 	}
 
-	ctxNames, err := kc.ContextNames()
-	if err != nil {
-		return fmt.Errorf("failed to get context names: %w", err)
-	}
-	if len(ctxNames) == 0 {
-		return errors.New("no contexts found in the kubeconfig file")
-	}
-
 	cmd := exec.Command("fzf", "--ansi", "--no-preview")
 	var out bytes.Buffer
 	cmd.Stdin = os.Stdin

cmd/kubectx/state.go

@@ -24,11 +24,11 @@ import (
 )
 
 func kubectxPrevCtxFile() (string, error) {
-	dir := cmdutil.CacheDir()
-	if dir == "" {
+	home := cmdutil.HomeDir()
+	if home == "" {
 		return "", errors.New("HOME or USERPROFILE environment variable not set")
 	}
-	return filepath.Join(dir, "kubectx"), nil
+	return filepath.Join(home, ".kube", "kubectx"), nil
 }
 
 // readLastContext returns the saved previous context

cmd/kubectx/state_test.go

@@ -73,7 +73,6 @@ func Test_writeLastContext(t *testing.T) {
 
 func Test_kubectxFilePath(t *testing.T) {
 	t.Setenv("HOME", filepath.FromSlash("/foo/bar"))
-	t.Setenv("XDG_CACHE_HOME", "")
 
 	expected := filepath.Join(filepath.FromSlash("/foo/bar"), ".kube", "kubectx")
 	v, err := kubectxPrevCtxFile()
@@ -85,19 +84,6 @@ func Test_kubectxFilePath(t *testing.T) {
 	}
 }
 
-func Test_kubectxFilePath_xdgCacheHome(t *testing.T) {
-	t.Setenv("XDG_CACHE_HOME", filepath.FromSlash("/tmp/xdg-cache"))
-
-	expected := filepath.Join(filepath.FromSlash("/tmp/xdg-cache"), "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) {
 	t.Setenv("HOME", "")
 	t.Setenv("USERPROFILE", "")

cmd/kubens/fzf.go

@@ -46,14 +46,6 @@ func (op InteractiveSwitchOp) Run(_, stderr io.Writer) error {
 		return fmt.Errorf("kubeconfig error: %w", err)
 	}
 
-	ctxNames, err := kc.ContextNames()
-	if err != nil {
-		return fmt.Errorf("failed to get context names: %w", err)
-	}
-	if len(ctxNames) == 0 {
-		return errors.New("no contexts found in the kubeconfig file")
-	}
-
 	cmd := exec.Command("fzf", "--ansi", "--no-preview")
 	var out bytes.Buffer
 	cmd.Stdin = os.Stdin

cmd/kubens/statefile.go

@@ -24,7 +24,7 @@ import (
 	"github.com/ahmetb/kubectx/internal/cmdutil"
 )
 
-var defaultDir = filepath.Join(cmdutil.CacheDir(), "kubens")
+var defaultDir = filepath.Join(cmdutil.HomeDir(), ".kube", "kubens")
 
 type NSFile struct {
 	dir string

cmd/kubens/statefile_test.go

@@ -18,6 +18,8 @@ import (
 	"runtime"
 	"strings"
 	"testing"
+
+	"github.com/ahmetb/kubectx/internal/testutil"
 )
 
 func TestNSFile(t *testing.T) {
@@ -48,7 +50,7 @@ func TestNSFile(t *testing.T) {
 }
 
 func TestNSFile_path_windows(t *testing.T) {
-	t.Setenv("_FORCE_GOOS", "windows")
+	defer testutil.WithEnvVar("_FORCE_GOOS", "windows")()
 	fp := NewNSFile("a:b:c").path()
 
 	if expected := "a__b__c"; !strings.HasSuffix(fp, expected) {
@@ -66,7 +68,7 @@ func Test_isWindows(t *testing.T) {
 		t.Fatalf("isWindows() returned true for %s", runtime.GOOS)
 	}
 
-	t.Setenv("_FORCE_GOOS", "windows")
+	defer testutil.WithEnvVar("_FORCE_GOOS", "windows")()
 	if !isWindows() {
 		t.Fatalf("isWindows() failed to detect windows with env override.")
 	}

internal/cmdutil/util.go

@@ -17,7 +17,6 @@ package cmdutil
 import (
 	"errors"
 	"os"
-	"path/filepath"
 )
 
 func HomeDir() string {
@@ -28,19 +27,6 @@ func HomeDir() string {
 	return home
 }
 
-// CacheDir returns XDG_CACHE_HOME if set, otherwise $HOME/.kube,
-// matching the bash scripts' behavior: ${XDG_CACHE_HOME:-$HOME/.kube}.
-func CacheDir() string {
-	if xdg := os.Getenv("XDG_CACHE_HOME"); xdg != "" {
-		return xdg
-	}
-	home := HomeDir()
-	if home == "" {
-		return ""
-	}
-	return filepath.Join(home, ".kube")
-}
-
 // IsNotFoundErr determines if the underlying error is os.IsNotExist.
 func IsNotFoundErr(err error) bool {
 	for e := err; e != nil; e = errors.Unwrap(e) {

internal/cmdutil/util_test.go

@@ -15,8 +15,9 @@
 package cmdutil
 
 import (
-	"path/filepath"
 	"testing"
+
+	"github.com/ahmetb/kubectx/internal/testutil"
 )
 
 func Test_homeDir(t *testing.T) {
@@ -62,40 +63,18 @@ func Test_homeDir(t *testing.T) {
 
 	for _, c := range cases {
 		t.Run(c.name, func(tt *testing.T) {
+			var unsets []func()
 			for _, e := range c.envs {
-				tt.Setenv(e.k, e.v)
+				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()
+			}
 		})
 	}
 }
-
-func TestCacheDir(t *testing.T) {
-	t.Run("XDG_CACHE_HOME set", func(t *testing.T) {
-		t.Setenv("XDG_CACHE_HOME", "/tmp/xdg-cache")
-		t.Setenv("HOME", "/home/user")
-		if got := CacheDir(); got != "/tmp/xdg-cache" {
-			t.Errorf("expected:%q got:%q", "/tmp/xdg-cache", got)
-		}
-	})
-	t.Run("XDG_CACHE_HOME unset, falls back to HOME/.kube", func(t *testing.T) {
-		t.Setenv("XDG_CACHE_HOME", "")
-		t.Setenv("HOME", "/home/user")
-		want := filepath.Join("/home/user", ".kube")
-		if got := CacheDir(); got != want {
-			t.Errorf("expected:%q got:%q", want, got)
-		}
-	})
-	t.Run("neither set", func(t *testing.T) {
-		t.Setenv("XDG_CACHE_HOME", "")
-		t.Setenv("HOME", "")
-		t.Setenv("USERPROFILE", "")
-		if got := CacheDir(); got != "" {
-			t.Errorf("expected:%q got:%q", "", got)
-		}
-	})
-}

internal/kubeconfig/kubeconfigloader_test.go

@@ -15,16 +15,17 @@
 package kubeconfig
 
 import (
+	"github.com/ahmetb/kubectx/internal/cmdutil"
 	"os"
 	"path/filepath"
 	"strings"
 	"testing"
 
-	"github.com/ahmetb/kubectx/internal/cmdutil"
+	"github.com/ahmetb/kubectx/internal/testutil"
 )
 
 func Test_kubeconfigPath(t *testing.T) {
-	t.Setenv("HOME", "/x/y/z")
+	defer testutil.WithEnvVar("HOME", "/x/y/z")()
 
 	expected := filepath.FromSlash("/x/y/z/.kube/config")
 	got, err := kubeconfigPath()
@@ -37,9 +38,9 @@ func Test_kubeconfigPath(t *testing.T) {
 }
 
 func Test_kubeconfigPath_noEnvVars(t *testing.T) {
-	t.Setenv("XDG_CACHE_HOME", "")
-	t.Setenv("HOME", "")
-	t.Setenv("USERPROFILE", "")
+	defer testutil.WithEnvVar("XDG_CACHE_HOME", "")()
+	defer testutil.WithEnvVar("HOME", "")()
+	defer testutil.WithEnvVar("USERPROFILE", "")()
 
 	_, err := kubeconfigPath()
 	if err == nil {
@@ -48,7 +49,7 @@ func Test_kubeconfigPath_noEnvVars(t *testing.T) {
 }
 
 func Test_kubeconfigPath_envOvveride(t *testing.T) {
-	t.Setenv("KUBECONFIG", "foo")
+	defer testutil.WithEnvVar("KUBECONFIG", "foo")()
 
 	v, err := kubeconfigPath()
 	if err != nil {
@@ -61,7 +62,7 @@ func Test_kubeconfigPath_envOvveride(t *testing.T) {
 
 func Test_kubeconfigPath_envOvverideDoesNotSupportPathSeparator(t *testing.T) {
 	path := strings.Join([]string{"file1", "file2"}, string(os.PathListSeparator))
-	t.Setenv("KUBECONFIG", path)
+	defer testutil.WithEnvVar("KUBECONFIG", path)()
 
 	_, err := kubeconfigPath()
 	if err == nil {
@@ -70,7 +71,7 @@ func Test_kubeconfigPath_envOvverideDoesNotSupportPathSeparator(t *testing.T) {
 }
 
 func TestStandardKubeconfigLoader_returnsNotFoundErr(t *testing.T) {
-	t.Setenv("KUBECONFIG", "foo")
+	defer testutil.WithEnvVar("KUBECONFIG", "foo")()
 	kc := new(Kubeconfig).WithLoader(DefaultLoader)
 	err := kc.Parse()
 	if err == nil {

internal/printer/color_test.go

@@ -18,6 +18,8 @@ import (
 	"testing"
 
 	"github.com/google/go-cmp/cmp"
+
+	"github.com/ahmetb/kubectx/internal/testutil"
 )
 
 var (
@@ -25,8 +27,8 @@ var (
 )
 
 func Test_useColors_forceColors(t *testing.T) {
-	t.Setenv("_KUBECTX_FORCE_COLOR", "1")
-	t.Setenv("NO_COLOR", "1")
+	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)
@@ -34,7 +36,7 @@ func Test_useColors_forceColors(t *testing.T) {
 }
 
 func Test_useColors_disableColors(t *testing.T) {
-	t.Setenv("NO_COLOR", "1")
+	defer testutil.WithEnvVar("NO_COLOR", "1")()
 
 	if v := useColors(); !cmp.Equal(v, &fa) {
 		t.Fatalf("expected useColors() = false; got = %v", v)
@@ -42,8 +44,8 @@ func Test_useColors_disableColors(t *testing.T) {
 }
 
 func Test_useColors_default(t *testing.T) {
-	t.Setenv("NO_COLOR", "")
-	t.Setenv("_KUBECTX_FORCE_COLOR", "")
+	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/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)
+		}
+	}
+}