refactor: implement custom completions for some flags using Go

Only --context, --cluster, --user and --namespace are included.

Signed-off-by: knight42 <anonymousknight96@gmail.com>
Signed-off-by: Marc Khouzam <marc.khouzam@montreal.ca>

staging/src/k8s.io/kubectl/pkg/cmd/cmd.go

@@ -325,15 +325,6 @@ __kubectl_custom_func() {
 
 const kubectlCmdHeaders = "KUBECTL_COMMAND_HEADERS"
 
-var (
-	bashCompletionFlags = map[string]string{
-		"namespace": "__kubectl_get_resource_namespace",
-		"context":   "__kubectl_config_get_contexts",
-		"cluster":   "__kubectl_config_get_clusters",
-		"user":      "__kubectl_config_get_users",
-	}
-)
-
 // NewDefaultKubectlCommand creates the `kubectl` command with default arguments
 func NewDefaultKubectlCommand() *cobra.Command {
 	return NewDefaultKubectlCommandWithArgs(NewDefaultPluginHandler(plugin.ValidPluginFilenamePrefixes), os.Args, os.Stdin, os.Stdout, os.Stderr)
@@ -633,17 +624,7 @@ func NewKubectlCommand(in io.Reader, out, err io.Writer) *cobra.Command {
 
 	templates.ActsAsRootCommand(cmds, filters, groups...)
 
-	for name, completion := range bashCompletionFlags {
-		if cmds.Flag(name) != nil {
-			if cmds.Flag(name).Annotations == nil {
-				cmds.Flag(name).Annotations = map[string][]string{}
-			}
-			cmds.Flag(name).Annotations[cobra.BashCompCustom] = append(
-				cmds.Flag(name).Annotations[cobra.BashCompCustom],
-				completion,
-			)
-		}
-	}
+	registerCompletionFuncForGlobalFlags(cmds, f)
 
 	cmds.AddCommand(alpha)
 	cmds.AddCommand(cmdconfig.NewCmdConfig(f, clientcmd.NewDefaultPathOptions(), ioStreams))

staging/src/k8s.io/kubectl/pkg/cmd/completion.go

@@ -0,0 +1,46 @@
+/*
+Copyright 2021 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 cmd
+
+import (
+	"github.com/spf13/cobra"
+	"k8s.io/kubectl/pkg/cmd/util"
+	"k8s.io/kubectl/pkg/completion"
+)
+
+func registerCompletionFuncForGlobalFlags(cmd *cobra.Command, f util.Factory) {
+	util.CheckErr(cmd.RegisterFlagCompletionFunc(
+		"namespace",
+		func(cmd *cobra.Command, args []string, toComplete string) ([]string, cobra.ShellCompDirective) {
+			return completion.ListNamespaces(f, toComplete)
+		}))
+	util.CheckErr(cmd.RegisterFlagCompletionFunc(
+		"context",
+		func(cmd *cobra.Command, args []string, toComplete string) ([]string, cobra.ShellCompDirective) {
+			return completion.ListContextsInKubeconfig(f, toComplete)
+		}))
+	util.CheckErr(cmd.RegisterFlagCompletionFunc(
+		"cluster",
+		func(cmd *cobra.Command, args []string, toComplete string) ([]string, cobra.ShellCompDirective) {
+			return completion.ListClustersInKubeconfig(f, toComplete)
+		}))
+	util.CheckErr(cmd.RegisterFlagCompletionFunc(
+		"user",
+		func(cmd *cobra.Command, args []string, toComplete string) ([]string, cobra.ShellCompDirective) {
+			return completion.ListUsersInKubeconfig(f, toComplete)
+		}))
+}

staging/src/k8s.io/kubectl/pkg/completion/utils.go

@@ -0,0 +1,94 @@
+/*
+Copyright 2021 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 completion
+
+import (
+	"context"
+	"strings"
+	"time"
+
+	"github.com/spf13/cobra"
+
+	metav1 "k8s.io/apimachinery/pkg/apis/meta/v1"
+	"k8s.io/kubectl/pkg/cmd/util"
+)
+
+// ListNamespaces returns a list of namespaces which begins with `toComplete`.
+func ListNamespaces(f util.Factory, toComplete string) ([]string, cobra.ShellCompDirective) {
+	clientSet, err := f.KubernetesClientSet()
+	if err != nil {
+		return nil, cobra.ShellCompDirectiveDefault
+	}
+	ctx, cancel := context.WithTimeout(context.TODO(), time.Second*3)
+	defer cancel()
+	namespaces, err := clientSet.CoreV1().Namespaces().List(ctx, metav1.ListOptions{})
+	if err != nil {
+		return nil, cobra.ShellCompDirectiveDefault
+	}
+	var ret []string
+	for _, ns := range namespaces.Items {
+		if strings.HasPrefix(ns.Name, toComplete) {
+			ret = append(ret, ns.Name)
+		}
+	}
+	return ret, cobra.ShellCompDirectiveNoFileComp
+}
+
+// ListContextsInKubeconfig returns a list of context names which begins with `toComplete`.
+func ListContextsInKubeconfig(f util.Factory, toComplete string) ([]string, cobra.ShellCompDirective) {
+	config, err := f.ToRawKubeConfigLoader().RawConfig()
+	if err != nil {
+		return nil, cobra.ShellCompDirectiveNoFileComp
+	}
+	var ret []string
+	for name := range config.Contexts {
+		if strings.HasPrefix(name, toComplete) {
+			ret = append(ret, name)
+		}
+	}
+	return ret, cobra.ShellCompDirectiveNoFileComp
+}
+
+// ListClustersInKubeconfig returns a list of cluster names which begins with `toComplete`.
+func ListClustersInKubeconfig(f util.Factory, toComplete string) ([]string, cobra.ShellCompDirective) {
+	config, err := f.ToRawKubeConfigLoader().RawConfig()
+	if err != nil {
+		return nil, cobra.ShellCompDirectiveNoFileComp
+	}
+	var ret []string
+	for name := range config.Clusters {
+		if strings.HasPrefix(name, toComplete) {
+			ret = append(ret, name)
+		}
+	}
+	return ret, cobra.ShellCompDirectiveNoFileComp
+}
+
+// ListUsersInKubeconfig returns a list of user names which begins with `toComplete`.
+func ListUsersInKubeconfig(f util.Factory, toComplete string) ([]string, cobra.ShellCompDirective) {
+	config, err := f.ToRawKubeConfigLoader().RawConfig()
+	if err != nil {
+		return nil, cobra.ShellCompDirectiveNoFileComp
+	}
+	var ret []string
+	for name := range config.AuthInfos {
+		if strings.HasPrefix(name, toComplete) {
+			ret = append(ret, name)
+		}
+	}
+	return ret, cobra.ShellCompDirectiveNoFileComp
+}

vendor/modules.txt

@@ -2070,6 +2070,7 @@ k8s.io/kubectl/pkg/cmd/util/podcmd
 k8s.io/kubectl/pkg/cmd/util/sanity
 k8s.io/kubectl/pkg/cmd/version
 k8s.io/kubectl/pkg/cmd/wait
+k8s.io/kubectl/pkg/completion
 k8s.io/kubectl/pkg/describe
 k8s.io/kubectl/pkg/drain
 k8s.io/kubectl/pkg/explain