feat(comp): Move kube-context completion to Go

Signed-off-by: Marc Khouzam <marc.khouzam@montreal.ca>

cmd/helm/helm.go

@@ -30,6 +30,7 @@ import (
 	// Import to initialize client auth plugins.
 	_ "k8s.io/client-go/plugin/pkg/client/auth"
 
+	"helm.sh/helm/v3/internal/completion"
 	"helm.sh/helm/v3/pkg/action"
 	"helm.sh/helm/v3/pkg/cli"
 	"helm.sh/helm/v3/pkg/gates"
@@ -67,6 +68,16 @@ func main() {
 	actionConfig := new(action.Configuration)
 	cmd := newRootCmd(actionConfig, os.Stdout, os.Args[1:])
 
+	if calledCmd, _, err := cmd.Find(os.Args[1:]); err == nil && calledCmd.Name() == completion.CompRequestCmd {
+		// If completion is being called, we have to check if the completion is for the "--kube-context"
+		// value; if it is, we cannot call the action.Init() method with an incomplete kube-context value
+		// or else it will fail immediately.  So, we simply unset the invalid kube-context value.
+		if args := os.Args[1:]; len(args) > 2 && args[len(args)-2] == "--kube-context" {
+			// We are completing the kube-context value!  Reset it as the current value is not valid.
+			settings.KubeContext = ""
+		}
+	}
+
 	if err := actionConfig.Init(settings.RESTClientGetter(), settings.Namespace(), os.Getenv("HELM_DRIVER"), debug); err != nil {
 		log.Fatal(err)
 	}

cmd/helm/root.go

@@ -24,6 +24,7 @@ import (
 	"github.com/spf13/cobra"
 
 	metav1 "k8s.io/apimachinery/pkg/apis/meta/v1"
+	"k8s.io/client-go/tools/clientcmd"
 
 	"helm.sh/helm/v3/cmd/helm/require"
 	"helm.sh/helm/v3/internal/completion"
@@ -31,30 +32,6 @@ import (
 	"helm.sh/helm/v3/pkg/action"
 )
 
-const (
-	contextCompFunc = `
-__helm_get_contexts()
-{
-    __helm_debug "${FUNCNAME[0]}: c is $c words[c] is ${words[c]}"
-    local template out
-    template="{{ range .contexts  }}{{ .name }} {{ end }}"
-    if out=$(kubectl config -o template --template="${template}" view 2>/dev/null); then
-        COMPREPLY=( $( compgen -W "${out[*]}" -- "$cur" ) )
-    fi
-}
-`
-)
-
-var (
-	// Mapping of global flags that can have dynamic completion and the
-	// completion function to be used.
-	bashCompletionFlags = map[string]string{
-		// Cannot convert the kube-context flag to Go completion yet because
-		// an incomplete kube-context will make actionConfig.Init() fail at the very start
-		"kube-context": "__helm_get_contexts",
-	}
-)
-
 var globalUsage = `The Kubernetes package manager
 
 Common actions for Helm:
@@ -101,14 +78,14 @@ func newRootCmd(actionConfig *action.Configuration, out io.Writer, args []string
 		Long:                   globalUsage,
 		SilenceUsage:           true,
 		Args:                   require.NoArgs,
-		BashCompletionFunction: fmt.Sprintf("%s%s", contextCompFunc, completion.GetBashCustomFunction()),
+		BashCompletionFunction: completion.GetBashCustomFunction(),
 	}
 	flags := cmd.PersistentFlags()
 
 	settings.AddFlags(flags)
 
-	flag := flags.Lookup("namespace")
 	// Setup shell completion for the namespace flag
+	flag := flags.Lookup("namespace")
 	completion.RegisterFlagCompletionFunc(flag, func(cmd *cobra.Command, args []string, toComplete string) ([]string, completion.BashCompDirective) {
 		if client, err := actionConfig.KubernetesClientSet(); err == nil {
 			// Choose a long enough timeout that the user notices somethings is not working
@@ -129,6 +106,29 @@ func newRootCmd(actionConfig *action.Configuration, out io.Writer, args []string
 		return nil, completion.BashCompDirectiveDefault
 	})
 
+	// Setup shell completion for the kube-context flag
+	flag = flags.Lookup("kube-context")
+	completion.RegisterFlagCompletionFunc(flag, func(cmd *cobra.Command, args []string, toComplete string) ([]string, completion.BashCompDirective) {
+		completion.CompDebugln("About to get the different kube-contexts")
+
+		loadingRules := clientcmd.NewDefaultClientConfigLoadingRules()
+		if len(settings.KubeConfig) > 0 {
+			loadingRules = &clientcmd.ClientConfigLoadingRules{ExplicitPath: settings.KubeConfig}
+		}
+		if config, err := clientcmd.NewNonInteractiveDeferredLoadingClientConfig(
+			loadingRules,
+			&clientcmd.ConfigOverrides{}).RawConfig(); err == nil {
+			ctxs := []string{}
+			for name := range config.Contexts {
+				if strings.HasPrefix(name, toComplete) {
+					ctxs = append(ctxs, name)
+				}
+			}
+			return ctxs, completion.BashCompDirectiveNoFileComp
+		}
+		return nil, completion.BashCompDirectiveNoFileComp
+	})
+
 	// We can safely ignore any errors that flags.Parse encounters since
 	// those errors will be caught later during the call to cmd.Execution.
 	// This call is required to gather configuration information prior to
@@ -173,19 +173,6 @@ func newRootCmd(actionConfig *action.Configuration, out io.Writer, args []string
 		completion.NewCompleteCmd(settings, out),
 	)
 
-	// Add annotation to flags for which we can generate completion choices
-	for name, completion := range bashCompletionFlags {
-		if cmd.Flag(name) != nil {
-			if cmd.Flag(name).Annotations == nil {
-				cmd.Flag(name).Annotations = map[string][]string{}
-			}
-			cmd.Flag(name).Annotations[cobra.BashCompCustom] = append(
-				cmd.Flag(name).Annotations[cobra.BashCompCustom],
-				completion,
-			)
-		}
-	}
-
 	// Add *experimental* subcommands
 	registryClient, err := registry.NewClient(
 		registry.ClientOptDebug(settings.Debug),

internal/completion/complete.go

@@ -35,9 +35,9 @@ import (
 // This should ultimately be pushed down into Cobra.
 // ==================================================================================
 
-// compRequestCmd Hidden command to request completion results from the program.
+// CompRequestCmd Hidden command to request completion results from the program.
 // Used by the shell completion script.
-const compRequestCmd = "__complete"
+const CompRequestCmd = "__complete"
 
 // Global map allowing to find completion functions for commands or flags.
 var validArgsFunctions = map[interface{}]func(cmd *cobra.Command, args []string, toComplete string) ([]string, BashCompDirective){}
@@ -123,7 +123,7 @@ __helm_custom_func()
         done < <(compgen -W "${out[*]}" -- "$cur")
     fi
 }
-`, compRequestCmd, BashCompDirectiveError, BashCompDirectiveNoSpace, BashCompDirectiveNoFileComp)
+`, CompRequestCmd, BashCompDirectiveError, BashCompDirectiveNoSpace, BashCompDirectiveNoFileComp)
 }
 
 // RegisterValidArgsFunc should be called to register a function to provide argument completion for a command
@@ -177,14 +177,14 @@ func (d BashCompDirective) string() string {
 func NewCompleteCmd(settings *cli.EnvSettings, out io.Writer) *cobra.Command {
 	debug = settings.Debug
 	return &cobra.Command{
-		Use:                   fmt.Sprintf("%s [command-line]", compRequestCmd),
+		Use:                   fmt.Sprintf("%s [command-line]", CompRequestCmd),
 		DisableFlagsInUseLine: true,
 		Hidden:                true,
 		DisableFlagParsing:    true,
 		Args:                  require.MinimumNArgs(1),
 		Short:                 "Request shell completion choices for the specified command-line",
 		Long: fmt.Sprintf("%s is a special command that is used by the shell completion logic\n%s",
-			compRequestCmd, "to request completion choices for the specified command-line."),
+			CompRequestCmd, "to request completion choices for the specified command-line."),
 		Run: func(cmd *cobra.Command, args []string) {
 			CompDebugln(fmt.Sprintf("%s was called with args %v", cmd.Name(), args))