feat: add --format flag to namespace ls command

cmd/nerdctl/namespace/namespace.go

@@ -17,19 +17,9 @@
 package namespace
 
 import (
-	"fmt"
-	"sort"
-	"strings"
-	"text/tabwriter"
-
 	"github.com/spf13/cobra"
 
-	"github.com/containerd/containerd/v2/pkg/namespaces"
-	"github.com/containerd/log"
-
 	"github.com/containerd/nerdctl/v2/cmd/nerdctl/helpers"
-	"github.com/containerd/nerdctl/v2/pkg/clientutil"
-	"github.com/containerd/nerdctl/v2/pkg/mountutil/volumestore"
 )
 
 func Command() *cobra.Command {
@@ -50,90 +40,3 @@ func Command() *cobra.Command {
 	cmd.AddCommand(inspectCommand())
 	return cmd
 }
-
-func listCommand() *cobra.Command {
-	cmd := &cobra.Command{
-		Use:           "ls",
-		Aliases:       []string{"list"},
-		Short:         "List containerd namespaces",
-		RunE:          listAction,
-		SilenceUsage:  true,
-		SilenceErrors: true,
-	}
-	cmd.Flags().BoolP("quiet", "q", false, "Only display names")
-	return cmd
-}
-
-func listAction(cmd *cobra.Command, args []string) error {
-	globalOptions, err := helpers.ProcessRootCmdFlags(cmd)
-	if err != nil {
-		return err
-	}
-	client, ctx, cancel, err := clientutil.NewClient(cmd.Context(), globalOptions.Namespace, globalOptions.Address)
-	if err != nil {
-		return err
-	}
-	defer cancel()
-
-	nsService := client.NamespaceService()
-	nsList, err := nsService.List(ctx)
-	if err != nil {
-		return err
-	}
-	quiet, err := cmd.Flags().GetBool("quiet")
-	if err != nil {
-		return err
-	}
-	if quiet {
-		for _, ns := range nsList {
-			fmt.Fprintln(cmd.OutOrStdout(), ns)
-		}
-		return nil
-	}
-	dataStore, err := clientutil.DataStore(globalOptions.DataRoot, globalOptions.Address)
-	if err != nil {
-		return err
-	}
-
-	w := tabwriter.NewWriter(cmd.OutOrStdout(), 4, 8, 4, ' ', 0)
-	// no "NETWORKS", because networks are global objects
-	fmt.Fprintln(w, "NAME\tCONTAINERS\tIMAGES\tVOLUMES\tLABELS")
-	for _, ns := range nsList {
-		ctx = namespaces.WithNamespace(ctx, ns)
-		var numContainers, numImages, numVolumes int
-		var labelStrings []string
-
-		containers, err := client.Containers(ctx)
-		if err != nil {
-			log.L.Warn(err)
-		}
-		numContainers = len(containers)
-
-		images, err := client.ImageService().List(ctx)
-		if err != nil {
-			log.L.Warn(err)
-		}
-		numImages = len(images)
-
-		volStore, err := volumestore.New(dataStore, ns)
-		if err != nil {
-			log.L.Warn(err)
-		} else {
-			numVolumes, err = volStore.Count()
-			if err != nil {
-				log.L.Warn(err)
-			}
-		}
-
-		labels, err := client.NamespaceService().Labels(ctx, ns)
-		if err != nil {
-			return err
-		}
-		for k, v := range labels {
-			labelStrings = append(labelStrings, strings.Join([]string{k, v}, "="))
-		}
-		sort.Strings(labelStrings)
-		fmt.Fprintf(w, "%s\t%d\t%d\t%d\t%v\t\n", ns, numContainers, numImages, numVolumes, strings.Join(labelStrings, ","))
-	}
-	return w.Flush()
-}

cmd/nerdctl/namespace/namespace_inspect.go

@@ -75,6 +75,5 @@ func inspectAction(cmd *cobra.Command, args []string) error {
 }
 
 func namespaceInspectShellComplete(cmd *cobra.Command, args []string, toComplete string) ([]string, cobra.ShellCompDirective) {
-	// show namespace names
 	return completion.NamespaceNames(cmd, args, toComplete)
 }

cmd/nerdctl/namespace/namespace_list.go

@@ -0,0 +1,76 @@
+/*
+   Copyright The containerd 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 namespace
+
+import (
+	"github.com/spf13/cobra"
+
+	"github.com/containerd/nerdctl/v2/cmd/nerdctl/helpers"
+	"github.com/containerd/nerdctl/v2/pkg/api/types"
+	"github.com/containerd/nerdctl/v2/pkg/clientutil"
+	"github.com/containerd/nerdctl/v2/pkg/cmd/namespace"
+)
+
+func listCommand() *cobra.Command {
+	cmd := &cobra.Command{
+		Use:           "ls",
+		Aliases:       []string{"list"},
+		Short:         "List containerd namespaces",
+		RunE:          listAction,
+		SilenceUsage:  true,
+		SilenceErrors: true,
+	}
+	cmd.Flags().BoolP("quiet", "q", false, "Only display names")
+	cmd.Flags().StringP("format", "f", "", "Format the output using the given Go template, e.g, '{{json .}}'")
+	return cmd
+}
+
+func listOptions(cmd *cobra.Command) (types.NamespaceListOptions, error) {
+	globalOptions, err := helpers.ProcessRootCmdFlags(cmd)
+	if err != nil {
+		return types.NamespaceListOptions{}, err
+	}
+	format, err := cmd.Flags().GetString("format")
+	if err != nil {
+		return types.NamespaceListOptions{}, err
+	}
+	quiet, err := cmd.Flags().GetBool("quiet")
+	if err != nil {
+		return types.NamespaceListOptions{}, err
+	}
+	return types.NamespaceListOptions{
+		GOptions: globalOptions,
+		Format:   format,
+		Quiet:    quiet,
+		Stdout:   cmd.OutOrStdout(),
+	}, nil
+}
+
+func listAction(cmd *cobra.Command, args []string) error {
+	options, err := listOptions(cmd)
+	if err != nil {
+		return err
+	}
+
+	client, ctx, cancel, err := clientutil.NewClient(cmd.Context(), options.GOptions.Namespace, options.GOptions.Address)
+	if err != nil {
+		return err
+	}
+	defer cancel()
+
+	return namespace.List(ctx, client, options)
+}

cmd/nerdctl/namespace/namespace_remove.go

@@ -73,6 +73,5 @@ func removeAction(cmd *cobra.Command, args []string) error {
 }
 
 func namespaceRemoveShellComplete(cmd *cobra.Command, args []string, toComplete string) ([]string, cobra.ShellCompDirective) {
-	// show namespace names
 	return completion.NamespaceNames(cmd, args, toComplete)
 }

cmd/nerdctl/namespace/namespace_update.go

@@ -71,6 +71,5 @@ func updateAction(cmd *cobra.Command, args []string) error {
 }
 
 func namespaceUpdateShellComplete(cmd *cobra.Command, args []string, toComplete string) ([]string, cobra.ShellCompDirective) {
-	// show namespace names
 	return completion.NamespaceNames(cmd, args, toComplete)
 }

docs/command-reference.md

@@ -1289,6 +1289,7 @@ Usage: `nerdctl namespace ls [OPTIONS]`
 Flags:
 
 - `-q, --quiet`: Only display namespace names
+- `-f, --format`: Format the output using the given Go template, e.g, `{{json .}}`
 
 ### :nerd_face: :blue_square: nerdctl namespace remove
 

pkg/api/types/namespace_types.go

@@ -43,3 +43,13 @@ type NamespaceInspectOptions struct {
 	// Format the output using the given Go template, e.g, '{{json .}}'
 	Format string
 }
+
+// NamespaceListOptions specifies options for `nerdctl namespace ls`.
+type NamespaceListOptions struct {
+	Stdout   io.Writer
+	GOptions GlobalCommandOptions
+	// Format the output using the given Go template, e.g, '{{json .}}'
+	Format string
+	// Quiet suppresses extra information and only prints namespace names
+	Quiet bool
+}

pkg/cmd/namespace/list.go

@@ -0,0 +1,153 @@
+/*
+   Copyright The containerd 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 namespace
+
+import (
+	"bytes"
+	"context"
+	"errors"
+	"fmt"
+	"sort"
+	"strings"
+	"text/tabwriter"
+	"text/template"
+
+	containerd "github.com/containerd/containerd/v2/client"
+	"github.com/containerd/containerd/v2/pkg/namespaces"
+	"github.com/containerd/log"
+
+	"github.com/containerd/nerdctl/v2/pkg/api/types"
+	"github.com/containerd/nerdctl/v2/pkg/clientutil"
+	"github.com/containerd/nerdctl/v2/pkg/formatter"
+	"github.com/containerd/nerdctl/v2/pkg/mountutil/volumestore"
+)
+
+func List(ctx context.Context, client *containerd.Client, options types.NamespaceListOptions) error {
+	nsStore := client.NamespaceService()
+	nsList, err := nsStore.List(ctx)
+	if err != nil {
+		return err
+	}
+
+	dataStore, err := clientutil.DataStore(options.GOptions.DataRoot, options.GOptions.Address)
+	if err != nil {
+		return err
+	}
+
+	w := options.Stdout
+	var tmpl *template.Template
+	namespaceList := []namespace{}
+	for _, ns := range nsList {
+		ctx = namespaces.WithNamespace(ctx, ns)
+		var numContainers, numImages, numVolumes int
+
+		containers, err := client.Containers(ctx)
+		if err != nil {
+			log.L.Warn(err)
+		}
+		numContainers = len(containers)
+
+		images, err := client.ImageService().List(ctx)
+		if err != nil {
+			log.L.Warn(err)
+		}
+		numImages = len(images)
+
+		volStore, err := volumestore.New(dataStore, ns)
+		if err != nil {
+			log.L.Warn(err)
+		} else {
+			numVolumes, err = volStore.Count()
+			if err != nil {
+				log.L.Warn(err)
+			}
+		}
+
+		labels, err := client.NamespaceService().Labels(ctx, ns)
+		if err != nil {
+			return err
+		}
+		namespaceList = append(namespaceList, namespace{
+			Name:       ns,
+			Containers: numContainers,
+			Images:     numImages,
+			Volumes:    numVolumes,
+			Labels:     labels,
+		})
+	}
+
+	switch options.Format {
+	case "", "table", "wide":
+		if !options.Quiet {
+			w = tabwriter.NewWriter(w, 4, 8, 4, ' ', 0)
+			// no "NETWORKS", because networks are global objects
+			fmt.Fprintln(w, "NAME\tCONTAINERS\tIMAGES\tVOLUMES\tLABELS")
+		}
+	case "raw":
+		return errors.New("unsupported format: \"raw\"")
+	default:
+		if options.Quiet {
+			return errors.New("format and quiet must not be specified together")
+		}
+		var err error
+		tmpl, err = formatter.ParseTemplate(options.Format)
+		if err != nil {
+			return err
+		}
+	}
+
+	for _, namespace := range namespaceList {
+		if tmpl != nil {
+			var b bytes.Buffer
+			if err := tmpl.Execute(&b, namespace); err != nil {
+				return err
+			}
+			if _, err := fmt.Fprintln(w, b.String()); err != nil {
+				return err
+			}
+		} else if options.Quiet {
+			if _, err := fmt.Fprintln(w, namespace.Name); err != nil {
+				return err
+			}
+		} else {
+			format := "%s\t%d\t%d\t%d\t%v\t\n"
+			var labelStrings []string
+			for k, v := range namespace.Labels {
+				labelStrings = append(labelStrings, strings.Join([]string{k, v}, "="))
+			}
+			sort.Strings(labelStrings)
+			args := []interface{}{}
+			args = append(args, namespace.Name, namespace.Containers, namespace.Images, namespace.Volumes, strings.Join(labelStrings, ","))
+			if _, err := fmt.Fprintf(w, format, args...); err != nil {
+				return err
+			}
+		}
+	}
+
+	if f, ok := w.(formatter.Flusher); ok {
+		return f.Flush()
+	}
+	return nil
+}
+
+type namespace struct {
+	Name       string
+	Containers int
+	Images     int
+	Volumes    int
+	Labels     map[string]string
+}