github/kubernetes
1
0
Fork 0
mirror of https://github.com/k3s-io/kubernetes.git synced 2025-08-10 12:32:03 +00:00
Code Issues Projects Releases Wiki Activity

Add support for shell completion for plugins

Browse Source 
When doing completion for arguments or flags for a plugin, kubectl will
call "kubectl_complete-<plugin>" to obtain the list of completions.
For example, for "krew" plugin, when the user triggers completion using:

$ kubectl krew <tab><tab>

kubectl will look for an executable file called "kubectl_complete-krew".
This file should print the list of valid completions for the plugin to
stdout.  Using cobra.ShellCompDirective as the last line of the output
is supported as is done by Cobra.

We also clear global flags when doing plugin completion because plugins
don't necessarily accept the global kubectl flags.  If some plugins do,
they will need to include such flags in their kubectl_complete-<plugin>
output.

Signed-off-by: Marc Khouzam <marc.khouzam@montreal.ca>
This commit is contained in:
Marc Khouzam 2021-09-15 21:44:07 -04:00 committed by Marc Khouzam
parent 3db3ff53cd
commit befc8da7ef
3 changed files with 239 additions and 52 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

9
staging/src/k8s.io/kubectl/pkg/cmd/cmd.go
View File

@ -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 {

51
staging/src/k8s.io/kubectl/pkg/cmd/completion/completion.go
View File

@ -17,17 +17,11 @@ limitations under the License.
package completion
import (
"bytes"
"fmt"
"io"
"io/ioutil"
"path/filepath"
"strings"
"github.com/spf13/cobra"
"k8s.io/cli-runtime/pkg/genericclioptions"
"k8s.io/kubectl/pkg/cmd/plugin"
cmdutil "k8s.io/kubectl/pkg/cmd/util"
"k8s.io/kubectl/pkg/util/i18n"
"k8s.io/kubectl/pkg/util/templates"
@ -161,7 +155,6 @@ func RunCompletion(out io.Writer, boilerPlate string, cmd *cobra.Command, args [
if !found {
return cmdutil.UsageErrorf(cmd, "Unsupported shell type %q.", args[0])
}
addPluginCommands(cmd.Root())
return run(out, boilerPlate, cmd.Parent())
}
@ -213,47 +206,3 @@ func runCompletionPwsh(out io.Writer, boilerPlate string, kubectl *cobra.Command
return kubectl.GenPowerShellCompletionWithDesc(out)
}
// addPluginCommand adds plugin commands under the given command so that
// completion includes them
func addPluginCommands(kubectl *cobra.Command) {
streams := genericclioptions.IOStreams{
In: &bytes.Buffer{},
Out: ioutil.Discard,
ErrOut: ioutil.Discard,
}
o := &plugin.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,
// 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,
// A Run is required for it to be a valid command
Run: func(cmd *cobra.Command, args []string) {},
}
parentCmd.AddCommand(cmd)
parentCmd = cmd
}
}
}

231
staging/src/k8s.io/kubectl/pkg/cmd/plugin/plugin_completion.go Normal file
View File

@ -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
}