support karmadactl config get-contexts

pkg/karmadactl/config/config.go

@@ -0,0 +1,52 @@
+/*
+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(NewCmdConfigGetContexts(parentCommand, streams, pathOptions))
+	return cmd
+}

pkg/karmadactl/config/config_printer.go

@@ -0,0 +1,80 @@
+/*
+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"
+	"io"
+	"sort"
+	"strings"
+
+	"k8s.io/cli-runtime/pkg/printers"
+	clientcmdapi "k8s.io/client-go/tools/clientcmd/api"
+)
+
+var (
+	getContextColumns = []string{"CURRENT", "NAME", "CLUSTER", "AUTHINFO", "NAMESPACE"}
+)
+
+type ConfigCmdPrinter struct {
+	out io.Writer
+}
+
+func NewConfigCmdPrinter(out io.Writer) *ConfigCmdPrinter {
+	return &ConfigCmdPrinter{out: out}
+}
+
+func (p *ConfigCmdPrinter) printGetContexts(names []string, config *clientcmdapi.Config, showHeaders, nameOnly bool) error {
+	w := printers.GetNewTabWriter(p.out)
+	defer w.Flush()
+
+	if showHeaders {
+		err := printContextHeaders(w, nameOnly)
+		if err != nil {
+			return err
+		}
+	}
+
+	sort.Strings(names)
+	for _, name := range names {
+		err := printContext(name, config.Contexts[name], w, nameOnly, config.CurrentContext == name)
+		if err != nil {
+			return err
+		}
+	}
+
+	return nil
+}
+
+func printContextHeaders(out io.Writer, nameOnly bool) error {
+	columnNames := getContextColumns
+	if nameOnly {
+		columnNames = columnNames[:1]
+	}
+	_, err := fmt.Fprintf(out, "%s\n", strings.Join(columnNames, "\t"))
+	return err
+}
+
+func printContext(name string, context *clientcmdapi.Context, w io.Writer, nameOnly, current bool) error {
+	if nameOnly {
+		_, err := fmt.Fprintf(w, "%s\n", name)
+		return err
+	}
+	prefix := " "
+	if current {
+		prefix = "*"
+	}
+	_, err := fmt.Fprintf(w, "%s\t%s\t%s\t%s\t%s\n", prefix, name, context.Cluster, context.AuthInfo, context.Namespace)
+	return err
+}

pkg/karmadactl/config/get_contexts.go

@@ -0,0 +1,133 @@
+/*
+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"
+
+	"github.com/spf13/cobra"
+	utilerrors "k8s.io/apimachinery/pkg/util/errors"
+	"k8s.io/apimachinery/pkg/util/sets"
+	"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"
+)
+
+// contains the assignable options from the args.
+type getContextsOptions struct {
+	configAccess clientcmd.ConfigAccess
+	nameOnly     bool
+	showHeaders  bool
+	contextNames []string
+
+	outputFormat string
+	noHeaders    bool
+	print        *ConfigCmdPrinter
+
+	genericclioptions.IOStreams
+}
+
+var (
+	getContextsLong = templates.LongDesc(i18n.T(`Display one or many contexts from the kubeconfig file.`))
+
+	getContextsExample = templates.Examples(`
+		# List all the contexts in your kubeconfig file
+		%[1]s config get-contexts
+
+		# Describe one context in your kubeconfig file
+		%[1]s config get-contexts my-context`)
+)
+
+// NewCmdConfigGetContexts creates a command object for the "get-contexts" action, which
+// retrieves one or more contexts from a kubeconfig.
+func NewCmdConfigGetContexts(parentCommand string, streams genericclioptions.IOStreams, configAccess clientcmd.ConfigAccess) *cobra.Command {
+	options := &getContextsOptions{
+		configAccess: configAccess,
+		IOStreams:    streams,
+	}
+
+	cmd := &cobra.Command{
+		Use:                   "get-contexts [(-o|--output=)name)]",
+		DisableFlagsInUseLine: true,
+		Short:                 i18n.T("Describe one or many contexts"),
+		Long:                  getContextsLong,
+		Example:               fmt.Sprintf(getContextsExample, parentCommand),
+		Run: func(cmd *cobra.Command, args []string) {
+			cmdutil.CheckErr(options.complete(cmd, args))
+			cmdutil.CheckErr(options.runGetContexts())
+		},
+	}
+
+	cmd.Flags().BoolVar(&options.noHeaders, "no-headers", options.noHeaders, "When using the default or custom-column output format, don't print headers (default print headers).")
+	cmd.Flags().StringVarP(&options.outputFormat, "output", "o", options.outputFormat, `Output format. One of: (name).`)
+	return cmd
+}
+
+// assigns getContextsOptions from the args.
+func (o *getContextsOptions) complete(cmd *cobra.Command, args []string) error {
+	supportedOutputTypes := sets.NewString("", "name")
+	if !supportedOutputTypes.Has(o.outputFormat) {
+		return fmt.Errorf("--output %v is not available in kubectl config get-contexts; resetting to default output format", o.outputFormat)
+	}
+
+	o.contextNames = args
+	o.nameOnly = false
+	if o.outputFormat == "name" {
+		o.nameOnly = true
+	}
+	o.showHeaders = true
+	if cmdutil.GetFlagBool(cmd, "no-headers") || o.nameOnly {
+		o.showHeaders = false
+	}
+
+	o.print = NewConfigCmdPrinter(o.Out)
+
+	return nil
+}
+
+// implements all the necessary functionality for context retrieval.
+func (o *getContextsOptions) runGetContexts() error {
+	config, err := o.configAccess.GetStartingConfig()
+	if err != nil {
+		return err
+	}
+
+	// Build a list of context names to print, and warn if any requested contexts are not found.
+	// Do this before printing the headers, so it doesn't look ugly.
+	var allErrs []error
+	var toPrint []string
+	if len(o.contextNames) == 0 {
+		for name := range config.Contexts {
+			toPrint = append(toPrint, name)
+		}
+	} else {
+		for _, name := range o.contextNames {
+			_, ok := config.Contexts[name]
+			if ok {
+				toPrint = append(toPrint, name)
+			} else {
+				allErrs = append(allErrs, fmt.Errorf("context %s not found", name))
+			}
+		}
+	}
+
+	err = o.print.printGetContexts(toPrint, config, o.showHeaders, o.nameOnly)
+	if err != nil {
+		allErrs = append(allErrs, err)
+	}
+
+	return utilerrors.NewAggregate(allErrs)
+}

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...)