support karmadactl config use-context to set the current-context in a kubeconfig file

pkg/karmadactl/config/config.go

@@ -0,0 +1,58 @@
+/*
+Copyright 2023 The Karmada 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 config
+
+import (
+	"fmt"
+	"path"
+
+	"github.com/spf13/cobra"
+	"k8s.io/cli-runtime/pkg/genericclioptions"
+	"k8s.io/client-go/tools/clientcmd"
+	cmdutil "k8s.io/kubectl/pkg/cmd/util"
+	"k8s.io/kubectl/pkg/util/i18n"
+	"k8s.io/kubectl/pkg/util/templates"
+)
+
+// NewCmdConfig creates a command object for the "config" action, and adds all child commands to it.
+func NewCmdConfig(parentCommand string, pathOptions *clientcmd.PathOptions, streams genericclioptions.IOStreams) *cobra.Command {
+	if len(pathOptions.ExplicitFileFlag) == 0 {
+		pathOptions.ExplicitFileFlag = clientcmd.RecommendedConfigPathFlag
+	}
+
+	cmd := &cobra.Command{
+		Use:                   "config SUBCOMMAND",
+		DisableFlagsInUseLine: true,
+		Short:                 i18n.T("Modify kubeconfig files"),
+		Long: fmt.Sprintf(templates.LongDesc(i18n.T(`
+			Modify kubeconfig files using subcommands like "%[1]s config set current-context my-context".
+
+			The loading order follows these rules:
+
+			1. If the --`)+pathOptions.ExplicitFileFlag+i18n.T(` flag is set, then only that file is loaded. The flag may only be set once and no merging takes place.
+			2. If $`)+pathOptions.EnvVar+i18n.T(` environment variable is set, then it is used as a list of paths (normal path delimiting rules for your system). These paths are merged. When a value is modified, it is modified in the file that defines the stanza. When a value is created, it is created in the first file that exists. If no files in the chain exist, then it creates the last file in the list.
+
+			3. Otherwise, `)+path.Join("${HOME}", pathOptions.GlobalFileSubpath)+i18n.T(` is used and no merging takes place.`)), parentCommand),
+		Run: cmdutil.DefaultSubCommandRun(streams.ErrOut),
+	}
+
+	// file paths are common to all sub commands
+	cmd.PersistentFlags().StringVar(&pathOptions.LoadingRules.ExplicitPath, pathOptions.ExplicitFileFlag, pathOptions.LoadingRules.ExplicitPath, "use a particular kubeconfig file")
+
+	cmd.AddCommand(NewCmdConfigUseContext(parentCommand, streams, pathOptions))
+	return cmd
+}

pkg/karmadactl/config/use-context.go

@@ -0,0 +1,110 @@
+/*
+Copyright 2023 The Karmada 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 config
+
+import (
+	"errors"
+	"fmt"
+
+	"github.com/spf13/cobra"
+	"k8s.io/cli-runtime/pkg/genericclioptions"
+	"k8s.io/client-go/tools/clientcmd"
+	clientcmdapi "k8s.io/client-go/tools/clientcmd/api"
+	cmdutil "k8s.io/kubectl/pkg/cmd/util"
+	"k8s.io/kubectl/pkg/util/completion"
+	"k8s.io/kubectl/pkg/util/i18n"
+	"k8s.io/kubectl/pkg/util/templates"
+)
+
+var (
+	useContextExample = templates.Examples(`
+		# Use the context for the minikube cluster
+		%[1]s config use-context minikube`)
+)
+
+type useContextOptions struct {
+	configAccess clientcmd.ConfigAccess
+	streams      genericclioptions.IOStreams
+	config       clientcmdapi.Config
+	contextName  string
+}
+
+// NewCmdConfigUseContext returns a Command instance for 'config use-context' sub command
+func NewCmdConfigUseContext(parentCommand string, streams genericclioptions.IOStreams, configAccess clientcmd.ConfigAccess) *cobra.Command {
+	options := &useContextOptions{
+		configAccess: configAccess,
+		streams:      streams,
+	}
+
+	cmd := &cobra.Command{
+		Use:                   "use-context CONTEXT_NAME",
+		DisableFlagsInUseLine: true,
+		Short:                 i18n.T("Set the current-context in a kubeconfig file"),
+		Aliases:               []string{"use"},
+		Long:                  `Set the current-context in a kubeconfig file.`,
+		Example:               fmt.Sprintf(useContextExample, parentCommand),
+		ValidArgsFunction:     completion.ContextCompletionFunc,
+		Run: func(cmd *cobra.Command, args []string) {
+			cmdutil.CheckErr(options.complete(cmd))
+			cmdutil.CheckErr(options.validate())
+			cmdutil.CheckErr(options.run())
+			fmt.Fprintf(streams.Out, "Switched to context %q.\n", options.contextName)
+		},
+	}
+
+	return cmd
+}
+
+func (o *useContextOptions) complete(cmd *cobra.Command) error {
+	endingArgs := cmd.Flags().Args()
+	if len(endingArgs) != 1 {
+		err := cmd.Help()
+		if err != nil {
+			fmt.Fprintf(o.streams.Out, "puts out the help for the command karmadactl config use-context failed: %s", err.Error())
+		}
+		return fmt.Errorf("Unexpected args: %v", endingArgs)
+	}
+
+	o.contextName = endingArgs[0]
+	return nil
+}
+
+func (o *useContextOptions) validate() error {
+	if len(o.contextName) == 0 {
+		return errors.New("empty context names are not allowed")
+	}
+
+	config, err := o.configAccess.GetStartingConfig()
+	if err != nil {
+		return err
+	}
+	o.config = *config
+
+	for name := range config.Contexts {
+		if name == o.contextName {
+			return nil
+		}
+	}
+
+	return fmt.Errorf("no context exists with the name: %q", o.contextName)
+}
+
+func (o *useContextOptions) run() error {
+	o.config.CurrentContext = o.contextName
+
+	return clientcmd.ModifyConfig(o.configAccess, o.config, true)
+}

pkg/karmadactl/karmadactl.go

@@ -24,13 +24,15 @@ import (
 	"github.com/spf13/cobra"
 	"github.com/spf13/pflag"
 	"k8s.io/cli-runtime/pkg/genericclioptions"
+	"k8s.io/client-go/tools/clientcmd"
 	apiserverflag "k8s.io/component-base/cli/flag"
 	"k8s.io/klog/v2"
 	"k8s.io/kubectl/pkg/util/templates"
 
 	"github.com/karmada-io/karmada/pkg/karmadactl/addons"
 	"github.com/karmada-io/karmada/pkg/karmadactl/apply"
 	"github.com/karmada-io/karmada/pkg/karmadactl/cmdinit"
+	"github.com/karmada-io/karmada/pkg/karmadactl/config"
 	"github.com/karmada-io/karmada/pkg/karmadactl/cordon"
 	"github.com/karmada-io/karmada/pkg/karmadactl/deinit"
 	"github.com/karmada-io/karmada/pkg/karmadactl/describe"
@@ -133,6 +135,7 @@ func NewKarmadaCtlCommand(cmdUse, parentCommand string) *cobra.Command {
 
 	rootCmd.AddCommand(sharedcommand.NewCmdVersion(parentCommand))
 	rootCmd.AddCommand(options.NewCmdOptions(parentCommand, ioStreams.Out))
+	rootCmd.AddCommand(config.NewCmdConfig(parentCommand, clientcmd.NewDefaultPathOptions(), ioStreams))
 
 	templates.ActsAsRootCommand(rootCmd, filters, groups...)