Add image squash command

cmd/nerdctl/image/image.go

@@ -42,6 +42,7 @@ func NewImageCommand() *cobra.Command {
 		NewLoadCommand(),
 		NewSaveCommand(),
 		NewTagCommand(),
+		NewSquashCommand(),
 		imageRmCommand(),
 		newImageConvertCommand(),
 		newImageInspectCommand(),

cmd/nerdctl/image/image_squash.go

@@ -0,0 +1,97 @@
+/*
+   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 image
+
+import (
+	"fmt"
+
+	"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/image"
+)
+
+func addSquashFlags(cmd *cobra.Command) {
+	cmd.Flags().IntP("last-n-layer", "n", 0, "The number of specify squashing the last N (N=layer-count) layers")
+	cmd.Flags().StringP("author", "a", "nerdctl", `Author (e.g., "nerdctl contributor <[email protected]>")`)
+	cmd.Flags().StringP("message", "m", "generated by nerdctl squash", "Commit message")
+}
+
+// NewSquashCommand returns a new `squash` command to compress the number of layers of the image
+func NewSquashCommand() *cobra.Command {
+	var squashCommand = &cobra.Command{
+		Use:           "squash [flags] SOURCE_IMAGE TARGET_IMAGE",
+		Short:         "Compress the number of layers of the image",
+		Args:          helpers.IsExactArgs(2),
+		RunE:          squashAction,
+		SilenceUsage:  true,
+		SilenceErrors: true,
+	}
+	addSquashFlags(squashCommand)
+	return squashCommand
+}
+
+func processSquashCommandFlags(cmd *cobra.Command, args []string) (options types.ImageSquashOptions, err error) {
+	globalOptions, err := helpers.ProcessRootCmdFlags(cmd)
+	if err != nil {
+		return options, err
+	}
+	layerN, err := cmd.Flags().GetInt("last-n-layer")
+	if err != nil {
+		return options, err
+	}
+	author, err := cmd.Flags().GetString("author")
+	if err != nil {
+		return options, err
+	}
+	message, err := cmd.Flags().GetString("message")
+	if err != nil {
+		return options, err
+	}
+
+	options = types.ImageSquashOptions{
+		GOptions: globalOptions,
+
+		Author:  author,
+		Message: message,
+
+		SourceImageRef:  args[0],
+		TargetImageName: args[1],
+
+		SquashLayerLastN: layerN,
+	}
+	return options, nil
+}
+
+func squashAction(cmd *cobra.Command, args []string) error {
+	options, err := processSquashCommandFlags(cmd, args)
+	if err != nil {
+		return err
+	}
+	if !options.GOptions.Experimental {
+		return fmt.Errorf("squash is an experimental feature, please enable experimental mode")
+	}
+	client, ctx, cancel, err := clientutil.NewClient(cmd.Context(), options.GOptions.Namespace, options.GOptions.Address)
+	if err != nil {
+		return err
+	}
+	defer cancel()
+
+	return image.Squash(ctx, client, options)
+}

cmd/nerdctl/image/image_squash_test.go

@@ -0,0 +1,100 @@
+/*
+   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 image
+
+import (
+	"fmt"
+	"testing"
+
+	"gotest.tools/v3/assert"
+
+	"github.com/containerd/nerdctl/v2/pkg/testutil"
+	"github.com/containerd/nerdctl/v2/pkg/testutil/nerdtest"
+	"github.com/containerd/nerdctl/v2/pkg/testutil/test"
+)
+
+func squashIdentifierName(identifier string) string {
+	return fmt.Sprintf("%s-squash", identifier)
+}
+
+func secondCommitedIdentifierName(identifier string) string {
+	return fmt.Sprintf("%s-second", identifier)
+}
+
+func TestSquash(t *testing.T) {
+	testCase := nerdtest.Setup()
+
+	require := test.Require(
+		test.Not(nerdtest.Docker),
+		nerdtest.CGroup,
+	)
+
+	testCase.SubTests = []*test.Case{
+		{
+			Description: "by last-n-layer",
+			Require:     require,
+			NoParallel:  true,
+			Cleanup: func(data test.Data, helpers test.Helpers) {
+				identifier := data.Identifier()
+				secondIdentifier := secondCommitedIdentifierName(identifier)
+				squashIdentifier := squashIdentifierName(identifier)
+				helpers.Anyhow("rm", "-f", identifier)
+				helpers.Anyhow("rm", "-f", secondIdentifier)
+				helpers.Anyhow("rm", "-f", squashIdentifier)
+
+				helpers.Anyhow("rmi", "-f", secondIdentifier)
+				helpers.Anyhow("rmi", "-f", identifier)
+				helpers.Anyhow("rmi", "-f", squashIdentifier)
+				helpers.Anyhow("image", "prune", "-f")
+			},
+			Setup: func(data test.Data, helpers test.Helpers) {
+				identifier := data.Identifier()
+				helpers.Ensure("run", "-d", "--name", identifier, testutil.CommonImage, "sleep", nerdtest.Infinity)
+				helpers.Ensure("exec", identifier, "sh", "-euxc", `echo hello-first-commit > /foo`)
+				helpers.Ensure("commit", "-c", `CMD ["cat", "/foo"]`, "-m", `first commit`, "--pause=true", identifier, identifier)
+				out := helpers.Capture("run", "--rm", identifier)
+				assert.Equal(t, out, "hello-first-commit\n")
+
+				secondIdentifier := secondCommitedIdentifierName(identifier)
+				helpers.Ensure("run", "-d", "--name", secondIdentifier, identifier, "sleep", nerdtest.Infinity)
+				helpers.Ensure("exec", secondIdentifier, "sh", "-euxc", `echo hello-second-commit > /bar && echo hello-squash-commit > /foo`)
+				helpers.Ensure("commit", "-c", `CMD ["cat", "/foo", "/bar"]`, "-m", `second commit`, "--pause=true", secondIdentifier, secondIdentifier)
+				out = helpers.Capture("run", "--rm", secondIdentifier)
+				assert.Equal(t, out, "hello-squash-commit\nhello-second-commit\n")
+
+				squashIdentifier := squashIdentifierName(identifier)
+				helpers.Ensure("image", "squash", "-n", "2", "-m", "squash commit", secondIdentifier, squashIdentifier)
+				out = helpers.Capture("run", "--rm", squashIdentifier)
+				assert.Equal(t, out, "hello-squash-commit\nhello-second-commit\n")
+			},
+			Command: func(data test.Data, helpers test.Helpers) test.TestableCommand {
+				identifier := data.Identifier()
+
+				squashIdentifier := squashIdentifierName(identifier)
+				return helpers.Command("image", "history", "--human=true", "--format=json", squashIdentifier)
+			},
+			Expected: test.Expects(0, nil, func(stdout string, info string, t *testing.T) {
+				history, err := decode(stdout)
+				assert.NilError(t, err, info)
+				assert.Equal(t, len(history), 3, info)
+				assert.Equal(t, history[0].Comment, "squash commit", info)
+			}),
+		},
+	}
+
+	testCase.Run(t)
+}

docs/command-reference.md

@@ -994,6 +994,24 @@ Flags:
 - `--platform=<PLATFORM>`        : Convert content for a specific platform
 - `--all-platforms`              : Convert content for all platforms (default: false)
 
+### :nerd_face: nerdctl image squash
+
+Squash last-n-layer into a single layer.
+
+Usage: `nerdctl image squash [OPTIONS] SOURCE_IMAGE[:TAG] TARGET_IMAGE[:TAG]`
+
+Example:
+
+```bash
+nerdctl image pull example.com/foo:latest
+nerdctl image squash ----last-n-layer=2 --message="generated by nerdctl squash" example.com/foo:latest example.com/foo:squashed
+```
+
+Flags:
+- `-n --last-n-layer=<NUMBER>`: The number of specify squashing the last N (N=layer-count) layers
+- `-m --message=<MESSAGE>`: Commit message for the squashed image
+- `-a --author=<AUTHOR>`: Author of the squashed image
+
 ## Registry
 
 ### :whale: nerdctl login

pkg/api/types/image_types.go

@@ -290,3 +290,21 @@ type SociOptions struct {
 	// Minimum layer size to build zTOC for. Smaller layers won't have zTOC and not lazy pulled. Default is 10 MiB.
 	MinLayerSize int64
 }
+
+// ImageSquashOptions specifies options for `nerdctl image squash`.
+type ImageSquashOptions struct {
+	// GOptions is the global options
+	GOptions GlobalCommandOptions
+
+	// Author (e.g., "nerdctl contributor <[email protected]>")
+	Author string
+	// Commit message
+	Message string
+	// SourceImageRef is the image to be squashed
+	SourceImageRef string
+	// TargetImageName is the name of the squashed image
+	TargetImageName string
+
+	// SquashLayerLastN is the number of layers to squash
+	SquashLayerLastN int
+}