cmd: support nerdctl manifeset inspect

- Add nerdctl manifest inspect to display image manifest details, with optional --verbose output.
- Implement manifest parsing, formatting, and related type definitions.
- Integrate the new command into the CLI.

Signed-off-by: ChengyuZhu6 <[email protected]>

Author: ChengyuZhu6

cmd/nerdctl/main.go

@@ -40,6 +40,7 @@ import (
 	"github.com/containerd/nerdctl/v2/cmd/nerdctl/internal"
 	"github.com/containerd/nerdctl/v2/cmd/nerdctl/ipfs"
 	"github.com/containerd/nerdctl/v2/cmd/nerdctl/login"
+	"github.com/containerd/nerdctl/v2/cmd/nerdctl/manifest"
 	"github.com/containerd/nerdctl/v2/cmd/nerdctl/namespace"
 	"github.com/containerd/nerdctl/v2/cmd/nerdctl/network"
 	"github.com/containerd/nerdctl/v2/cmd/nerdctl/system"
@@ -344,6 +345,9 @@ Config file ($NERDCTL_TOML): %s
 
 		// IPFS
 		ipfs.NewIPFSCommand(),
+
+		// Manifest
+		manifest.Command(),
 	)
 	addApparmorCommand(rootCmd)
 	container.AddCpCommand(rootCmd)

cmd/nerdctl/manifest/manifest.go

@@ -0,0 +1,40 @@
+/*
+   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 manifest
+
+import (
+	"github.com/spf13/cobra"
+
+	"github.com/containerd/nerdctl/v2/cmd/nerdctl/helpers"
+)
+
+func Command() *cobra.Command {
+	cmd := &cobra.Command{
+		Annotations:   map[string]string{helpers.Category: helpers.Management},
+		Use:           "manifest",
+		Short:         "Manage image manifests.",
+		RunE:          helpers.UnknownSubcommandAction,
+		SilenceUsage:  true,
+		SilenceErrors: true,
+	}
+
+	cmd.AddCommand(
+		InspectCommand(),
+	)
+
+	return cmd
+}

cmd/nerdctl/manifest/manifest_inspect.go

@@ -0,0 +1,95 @@
+/*
+   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 manifest
+
+import (
+	"fmt"
+
+	"github.com/spf13/cobra"
+
+	"github.com/containerd/nerdctl/v2/cmd/nerdctl/completion"
+	"github.com/containerd/nerdctl/v2/cmd/nerdctl/helpers"
+	"github.com/containerd/nerdctl/v2/pkg/api/types"
+	"github.com/containerd/nerdctl/v2/pkg/cmd/manifest"
+	"github.com/containerd/nerdctl/v2/pkg/formatter"
+)
+
+func InspectCommand() *cobra.Command {
+	var cmd = &cobra.Command{
+		Use:               "inspect MANIFEST",
+		Short:             "Display the contents of a manifest or image index/manifest list",
+		Args:              cobra.MinimumNArgs(1),
+		RunE:              inspectAction,
+		ValidArgsFunction: inspectShellComplete,
+		SilenceUsage:      true,
+		SilenceErrors:     true,
+	}
+	cmd.Flags().Bool("verbose", false, "Verbose output additional info including layers and platform")
+	cmd.Flags().Bool("insecure", false, "Allow communication with an insecure registry")
+	return cmd
+}
+
+func processInspectFlags(cmd *cobra.Command) (types.ManifestInspectOptions, error) {
+	globalOptions, err := helpers.ProcessRootCmdFlags(cmd)
+	if err != nil {
+		return types.ManifestInspectOptions{}, err
+	}
+	verbose, err := cmd.Flags().GetBool("verbose")
+	if err != nil {
+		return types.ManifestInspectOptions{}, err
+	}
+	insecure, err := cmd.Flags().GetBool("insecure")
+	if err != nil {
+		return types.ManifestInspectOptions{}, err
+	}
+	return types.ManifestInspectOptions{
+		Stdout:   cmd.OutOrStdout(),
+		GOptions: globalOptions,
+		Verbose:  verbose,
+		Insecure: insecure,
+	}, nil
+}
+
+func inspectAction(cmd *cobra.Command, args []string) error {
+	inspectOptions, err := processInspectFlags(cmd)
+	if err != nil {
+		return err
+	}
+	rawRef := args[0]
+	res, err := manifest.Inspect(cmd.Context(), rawRef, inspectOptions)
+	if err != nil {
+		return err
+	}
+
+	// Output format: single object for single result, array for multiple results
+	if len(res) == 1 {
+		jsonStr, err := formatter.ToJSON(res[0], "", "    ")
+		if err != nil {
+			return err
+		}
+		fmt.Fprint(inspectOptions.Stdout, jsonStr)
+	} else {
+		if formatErr := formatter.FormatSlice("", inspectOptions.Stdout, res); formatErr != nil {
+			return formatErr
+		}
+	}
+	return nil
+}
+
+func inspectShellComplete(cmd *cobra.Command, args []string, toComplete string) ([]string, cobra.ShellCompDirective) {
+	return completion.ImageNames(cmd)
+}

pkg/api/types/manifest_types.go

@@ -0,0 +1,29 @@
+/*
+   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 types
+
+import "io"
+
+// ManifestInspectOptions specifies options for `nerdctl manifest inspect`.
+type ManifestInspectOptions struct {
+	Stdout   io.Writer
+	GOptions GlobalCommandOptions
+	// Verbose output additional info including layers and platform
+	Verbose bool
+	// Allow communication with an insecure registry
+	Insecure bool
+}