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Merge pull request #105867 from VilledeMontreal/feature/compPlugins

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Shell completion for plugins
This commit is contained in:
Kubernetes Prow Robot 2022-10-25 16:26:34 -07:00 committed by GitHub
commit 797536fc76
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6 changed files with 370 additions and 50 deletions
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9
staging/src/k8s.io/kubectl/pkg/cmd/cmd.go
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@ -279,8 +279,15 @@ func NewKubectlCommand(o KubectlOptions) *cobra.Command {
Run: runHelp,
// Hook before and after Run initialize and write profiles to disk,
// respectively.
PersistentPreRunE: func(*cobra.Command, []string) error {
PersistentPreRunE: func(cmd *cobra.Command, args []string) error {
rest.SetDefaultWarningHandler(warningHandler)
if cmd.Name() == cobra.ShellCompRequestCmd {
// This is the __complete or __completeNoDesc command which
// indicates shell completion has been requested.
plugin.SetupPluginCompletion(cmd, args)
}
return initProfiling()
},
PersistentPostRunE: func(*cobra.Command, []string) error {

103
staging/src/k8s.io/kubectl/pkg/cmd/plugin/plugin.go
View File

@ -115,58 +115,27 @@ func (o *PluginListOptions) Complete(cmd *cobra.Command) error {
}
func (o *PluginListOptions) Run() error {
pluginsFound := false
isFirstFile := true
pluginErrors := []error{}
pluginWarnings := 0
plugins, pluginErrors := o.ListPlugins()
for _, dir := range uniquePathsList(o.PluginPaths) {
if len(strings.TrimSpace(dir)) == 0 {
continue
}
files, err := ioutil.ReadDir(dir)
if err != nil {
if _, ok := err.(*os.PathError); ok {
fmt.Fprintf(o.ErrOut, "Unable to read directory %q from your PATH: %v. Skipping...\n", dir, err)
continue
}
pluginErrors = append(pluginErrors, fmt.Errorf("error: unable to read directory %q in your PATH: %v", dir, err))
continue
}
for _, f := range files {
if f.IsDir() {
continue
}
if !hasValidPrefix(f.Name(), ValidPluginFilenamePrefixes) {
continue
}
if isFirstFile {
fmt.Fprintf(o.Out, "The following compatible plugins are available:\n\n")
pluginsFound = true
isFirstFile = false
}
pluginPath := f.Name()
if !o.NameOnly {
pluginPath = filepath.Join(dir, pluginPath)
}
fmt.Fprintf(o.Out, "%s\n", pluginPath)
if errs := o.Verifier.Verify(filepath.Join(dir, f.Name())); len(errs) != 0 {
for _, err := range errs {
fmt.Fprintf(o.ErrOut, " - %s\n", err)
pluginWarnings++
}
}
}
if len(plugins) > 0 {
fmt.Fprintf(o.Out, "The following compatible plugins are available:\n\n")
} else {
pluginErrors = append(pluginErrors, fmt.Errorf("error: unable to find any kubectl plugins in your PATH"))
}
if !pluginsFound {
pluginErrors = append(pluginErrors, fmt.Errorf("error: unable to find any kubectl plugins in your PATH"))
pluginWarnings := 0
for _, pluginPath := range plugins {
if o.NameOnly {
fmt.Fprintf(o.Out, "%s\n", filepath.Base(pluginPath))
} else {
fmt.Fprintf(o.Out, "%s\n", pluginPath)
}
if errs := o.Verifier.Verify(pluginPath); len(errs) != 0 {
for _, err := range errs {
fmt.Fprintf(o.ErrOut, " - %s\n", err)
pluginWarnings++
}
}
}
if pluginWarnings > 0 {
@ -187,6 +156,42 @@ func (o *PluginListOptions) Run() error {
return nil
}
// ListPlugins returns list of plugin paths.
func (o *PluginListOptions) ListPlugins() ([]string, []error) {
plugins := []string{}
errors := []error{}
for _, dir := range uniquePathsList(o.PluginPaths) {
if len(strings.TrimSpace(dir)) == 0 {
continue
}
files, err := ioutil.ReadDir(dir)
if err != nil {
if _, ok := err.(*os.PathError); ok {
fmt.Fprintf(o.ErrOut, "Unable to read directory %q from your PATH: %v. Skipping...\n", dir, err)
continue
}
errors = append(errors, fmt.Errorf("error: unable to read directory %q in your PATH: %v", dir, err))
continue
}
for _, f := range files {
if f.IsDir() {
continue
}
if !hasValidPrefix(f.Name(), ValidPluginFilenamePrefixes) {
continue
}
plugins = append(plugins, filepath.Join(dir, f.Name()))
}
}
return plugins, errors
}
// pathVerifier receives a path and determines if it is valid or not
type PathVerifier interface {
// Verify determines if a given path is valid

231
staging/src/k8s.io/kubectl/pkg/cmd/plugin/plugin_completion.go Normal file
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@ -0,0 +1,231 @@
/*
Copyright 2022 The Kubernetes Authors.
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 plugin
import (
"bytes"
"fmt"
"io/ioutil"
"os"
"os/exec"
"path/filepath"
"strconv"
"strings"
"github.com/spf13/cobra"
"k8s.io/cli-runtime/pkg/genericclioptions"
)
// SetupPluginCompletion adds a Cobra command to the command tree for each
// plugin. This is only done when performing shell completion that relate
// to plugins.
func SetupPluginCompletion(cmd *cobra.Command, args []string) {
if len(args) > 0 {
if strings.HasPrefix(args[0], "-") {
// Plugins are not supported if the first argument is a flag,
// so no need to add them in that case.
return
}
if len(args) == 1 {
// We are completing a subcommand at the first level so
// we should include all plugins names.
addPluginCommands(cmd)
return
}
// We have more than one argument.
// Check if we know the first level subcommand.
// If we don't it could be a plugin and we'll need to add
// the plugin commands for completion to work.
found := false
for _, subCmd := range cmd.Root().Commands() {
if args[0] == subCmd.Name() {
found = true
break
}
}
if !found {
// We don't know the subcommand for which completion
// is being called: it could be a plugin.
//
// When using a plugin, the kubectl global flags are not supported.
// Therefore, when doing completion, we need to remove these flags
// to avoid them being included in the completion choices.
// This must be done *before* adding the plugin commands so that
// when creating those plugin commands, the flags don't exist.
cmd.Root().ResetFlags()
cobra.CompDebugln("Cleared global flags for plugin completion", true)
addPluginCommands(cmd)
}
}
}
// addPluginCommand adds a Cobra command to the command tree
// for each plugin so that the completion logic knows about the plugins
func addPluginCommands(cmd *cobra.Command) {
kubectl := cmd.Root()
streams := genericclioptions.IOStreams{
In: &bytes.Buffer{},
Out: ioutil.Discard,
ErrOut: ioutil.Discard,
}
o := &PluginListOptions{IOStreams: streams}
o.Complete(kubectl)
plugins, _ := o.ListPlugins()
for _, plugin := range plugins {
plugin = filepath.Base(plugin)
args := []string{}
// Plugins are named "kubectl-<name>" or with more - such as
// "kubectl-<name>-<subcmd1>..."
for _, arg := range strings.Split(plugin, "-")[1:] {
// Underscores (_) in plugin's filename are replaced with dashes(-)
// e.g. foo_bar -> foo-bar
args = append(args, strings.Replace(arg, "_", "-", -1))
}
// In order to avoid that the same plugin command is added more than once,
// find the lowest command given args from the root command
parentCmd, remainingArgs, _ := kubectl.Find(args)
if parentCmd == nil {
parentCmd = kubectl
}
for _, remainingArg := range remainingArgs {
cmd := &cobra.Command{
Use: remainingArg,
// Add a description that will be shown with completion choices.
// Make each one different by including the plugin name to avoid
// all plugins being grouped in a single line during completion for zsh.
Short: fmt.Sprintf("The command %s is a plugin installed by the user", remainingArg),
DisableFlagParsing: true,
// Allow plugins to provide their own completion choices
ValidArgsFunction: pluginCompletion,
// A Run is required for it to be a valid command
Run: func(cmd *cobra.Command, args []string) {},
}
parentCmd.AddCommand(cmd)
parentCmd = cmd
}
}
}
// pluginCompletion deals with shell completion beyond the plugin name, it allows to complete
// plugin arguments and flags.
// It will look on $PATH for a specific executable file that will provide completions
// for the plugin in question.
//
// When called, this completion executable should print the completion choices to stdout.
// The arguments passed to the executable file will be the arguments for the plugin currently
// on the command-line. For example, if a user types:
//
// kubectl myplugin arg1 arg2 a<TAB>
//
// the completion executable will be called with arguments: "arg1" "arg2" "a".
// And if a user types:
//
// kubectl myplugin arg1 arg2 <TAB>
//
// the completion executable will be called with arguments: "arg1" "arg2" "". Notice the empty
// last argument which indicates that a new word should be completed but that the user has not
// typed anything for it yet.
//
// Kubectl's plugin completion logic supports Cobra's ShellCompDirective system. This means a plugin
// can optionally print :<value of a shell completion directive> as its very last line to provide
// directives to the shell on how to perform completion. If this directive is not present, the
// cobra.ShellCompDirectiveDefault will be used. Please see Cobra's documentation for more details:
// https://github.com/spf13/cobra/blob/master/shell_completions.md#dynamic-completion-of-nouns
//
// The completion executable should be named kubectl_complete-<plugin>. For example, for a plugin
// named kubectl-get_all, the completion file should be named kubectl_complete-get_all. The completion
// executable must have executable permissions set on it and must be on $PATH.
func pluginCompletion(cmd *cobra.Command, args []string, toComplete string) ([]string, cobra.ShellCompDirective) {
// Recreate the plugin name from the commandPath
pluginName := strings.Replace(strings.Replace(cmd.CommandPath(), "-", "_", -1), " ", "-", -1)
path, found := lookupCompletionExec(pluginName)
if !found {
cobra.CompDebugln(fmt.Sprintf("Plugin %s does not provide a matching completion executable", pluginName), true)
return nil, cobra.ShellCompDirectiveDefault
}
args = append(args, toComplete)
cobra.CompDebugln(fmt.Sprintf("About to call: %s %s", path, strings.Join(args, " ")), true)
return getPluginCompletions(path, args, os.Environ())
}
// lookupCompletionExec will look for the existence of an executable
// that can provide completion for the given plugin name.
// The first filepath to match is returned, or a boolean false if
// such an executable is not found.
func lookupCompletionExec(pluginName string) (string, bool) {
// Convert the plugin name into the plugin completion name by inserting "_complete" before the first -.
// For example, convert kubectl-get_all to kubectl_complete-get_all
pluginCompExec := strings.Replace(pluginName, "-", "_complete-", 1)
cobra.CompDebugln(fmt.Sprintf("About to look for: %s", pluginCompExec), true)
path, err := exec.LookPath(pluginCompExec)
if err != nil || len(path) == 0 {
return "", false
}
return path, true
}
// getPluginCompletions receives an executable's filepath, a slice
// of arguments, and a slice of environment variables
// to relay to the executable.
// The executable is responsible for printing the completions of the
// plugin for the current set of arguments.
func getPluginCompletions(executablePath string, cmdArgs, environment []string) ([]string, cobra.ShellCompDirective) {
buf := new(bytes.Buffer)
prog := exec.Command(executablePath, cmdArgs...)
prog.Stdin = os.Stdin
prog.Stdout = buf
prog.Stderr = os.Stderr
prog.Env = environment
var comps []string
directive := cobra.ShellCompDirectiveDefault
if err := prog.Run(); err == nil {
for _, comp := range strings.Split(buf.String(), "\n") {
// Remove any empty lines
if len(comp) > 0 {
comps = append(comps, comp)
}
}
// Check if the last line of output is of the form :<integer>, which
// indicates a Cobra ShellCompDirective. We do this for plugins
// that use Cobra or the ones that wish to use this directive to
// communicate a special behavior for the shell.
if len(comps) > 0 {
lastLine := comps[len(comps)-1]
if len(lastLine) > 1 && lastLine[0] == ':' {
if strInt, err := strconv.Atoi(lastLine[1:]); err == nil {
directive = cobra.ShellCompDirective(strInt)
comps = comps[:len(comps)-1]
}
}
}
}
return comps, directive
}

30
staging/src/k8s.io/kubectl/pkg/cmd/plugin/plugin_test.go
View File

@ -20,6 +20,8 @@ import (
"fmt"
"io/ioutil"
"os"
"path/filepath"
"reflect"
"strings"
"testing"
@ -178,6 +180,34 @@ func TestPluginPathsAreValid(t *testing.T) {
}
}
func TestListPlugins(t *testing.T) {
pluginPath, _ := filepath.Abs("./testdata")
expectPlugins := []string{
filepath.Join(pluginPath, "kubectl-foo"),
filepath.Join(pluginPath, "kubectl-version"),
}
verifier := newFakePluginPathVerifier()
ioStreams, _, _, _ := genericclioptions.NewTestIOStreams()
pluginPaths := []string{pluginPath}
o := &PluginListOptions{
Verifier: verifier,
IOStreams: ioStreams,
PluginPaths: pluginPaths,
}
plugins, errs := o.ListPlugins()
if len(errs) > 0 {
t.Fatalf("unexpected errors: %v", errs)
}
if !reflect.DeepEqual(expectPlugins, plugins) {
t.Fatalf("saw unexpected plugins. Expecting %v, got %v", expectPlugins, plugins)
}
}
type duplicatePathError struct {
path string
}

23
staging/src/k8s.io/sample-cli-plugin/README.md
View File

@ -58,6 +58,29 @@ that kubectl points to.
It can also be used as a means of showcasing usage of the cli-runtime set of utilities to aid in
third-party plugin development.
## Shell completion
This plugin supports shell completion when used through kubectl. To enable shell completion for the plugin
you must copy the file `./kubectl_complete-ns` somewhere on `$PATH` and give it executable permissions.
The `./kubectl_complete-ns` script shows a hybrid approach to providing completions:
1. it uses the builtin `__complete` command provided by [Cobra](https://github.com/spf13/cobra) for flags
1. it calls `kubectl` to obtain the list of namespaces to complete arguments (note that a more elegant approach would be to have the `kubectl-ns` program itself provide completion of arguments by implementing Cobra's `ValidArgsFunction` to fetch the list of namespaces, but it would then be a less varied example)
One can then do things like:
```
$ kubectl ns <TAB>
default kube-node-lease kube-public kube-system
$ kubectl ns --<TAB>
--as -- Username to impersonate for the operation. User could be a regular user or a service account in a namespace.
--as-group -- Group to impersonate for the operation, this flag can be repeated to specify multiple groups.
--as-uid -- UID to impersonate for the operation.
--cache-dir -- Default cache directory
[...]
```
Note: kubectl v1.26 or higher is required for shell completion to work for plugins.
## Cleanup
You can "uninstall" this plugin from kubectl by simply removing it from your PATH:

24
staging/src/k8s.io/sample-cli-plugin/kubectl_complete-ns Executable file
View File

@ -0,0 +1,24 @@
#!/usr/bin/env bash
# If we are completing a flag, use Cobra's builtin completion system.
# To know if we are completing a flag we need the last argument starts with a `-` and does not contain an `=`
args=("$@")
lastArg=${args[((${#args[@]}-1))]}
if [[ "$lastArg" == -* ]]; then
if [[ "$lastArg" != *=* ]]; then
kubectl ns __complete "$@"
fi
else
# TODO Make sure we are not completing the value of a flag.
# TODO Only complete a single argument.
# Both are pretty hard to do in a shell script. The better way to do this would be to let
# Cobra do all the completions by using `cobra.ValidArgsFunction` in the program.
# But the below, although imperfect, is a nice example for plugins that don't use Cobra.
# We are probably completing an argument. This plugin only accepts namespaces, let's fetch them.
kubectl get namespaces --output go-template='{{ range .items }}{{ .metadata.name }}{{"\n"}}{{ end }}'
# Turn off file completion. See the ShellCompDirective documentation within
# https://github.com/spf13/cobra/blob/main/shell_completions.md#completion-of-nouns
echo :4
fi