Add image squash ut & Update docs/command-reference.md

Signed-off-by: weipeng <weip3@chinatelecom.cn>

Author: weipeng

cmd/nerdctl/image/image_squash.go

@@ -34,6 +34,7 @@ func addSquashFlags(cmd *cobra.Command) {
 	cmd.Flags().StringP("message", "m", "", "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 TAG_IMAGE",

cmd/nerdctl/image/image_squash_test.go

@@ -0,0 +1,101 @@
+/*
+   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.Linux,
+		test.Not(nerdtest.Docker),
+		nerdtest.CGroup,
+	)
+
+	testCase.SubTests = []*test.Case{
+		{
+			Description: "by layer count",
+			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", "-c", "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)
+}

cmd/nerdctl/main.go

@@ -295,7 +295,6 @@ Config file ($NERDCTL_TOML): %s
 		image.NewTagCommand(),
 		image.NewRmiCommand(),
 		image.NewHistoryCommand(),
-		image.NewSquashCommand(),
 		// #endregion
 
 		// #region System

docs/command-reference.md

@@ -973,6 +973,25 @@ Flags:
 - `--platform=<PLATFORM>`        : Convert content for a specific platform
 - `--all-platforms`              : Convert content for all platforms (default: false)
 
+### :nerd_face: nerdctl image squash
+
+Squash an image layers.
+
+Usage: `nerdctl image squash [OPTIONS] SOURCE_IMAGE[:TAG] TARGET_IMAGE[:TAG]`
+
+Example:
+
+```bash
+nerdctl image pull example.com/foo:latest
+nerdctl image squash --layer-count=2 --message="squash commit" example.com/foo:latest example.com/foo:squashed
+```
+
+Flags:
+- `-c --layer-count=<COUNT>`: The number of layers that can be compressed
+- `-d --layer-digest=<DIGEST>`: The digest of the layer to be compressed
+- `-m --message=<MESSAGE>`: Commit message for the squashed image
+- `-a --author=<AUTHOR>`: Author of the squashed image
+
 ## Registry
 
 ### :whale: nerdctl login

pkg/cmd/image/squash.go

@@ -44,20 +44,23 @@ import (
 	"github.com/containerd/log"
 
 	"github.com/containerd/nerdctl/v2/pkg/api/types"
+	"github.com/containerd/nerdctl/v2/pkg/idutil/imagewalker"
 	"github.com/containerd/nerdctl/v2/pkg/imgutil"
 )
 
 const (
 	emptyDigest = digest.Digest("")
 )
 
+// squashImage is the image for squash operation
 type squashImage struct {
-	ClientImage containerd.Image
-	Config      ocispec.Image
-	Image       images.Image
-	Manifest    *ocispec.Manifest
+	clientImage containerd.Image
+	config      ocispec.Image
+	image       images.Image
+	manifest    *ocispec.Manifest
 }
 
+// squashRuntime is the runtime for squash operation
 type squashRuntime struct {
 	opt types.ImageSquashOptions
 
@@ -70,6 +73,7 @@ type squashRuntime struct {
 	snapshotter  snapshots.Snapshotter
 }
 
+// initImage initializes the squashImage based on the source image reference
 func (sr *squashRuntime) initImage(ctx context.Context) (*squashImage, error) {
 	containerImage, err := sr.imageStore.Get(ctx, sr.opt.SourceImageRef)
 	if err != nil {
@@ -86,20 +90,21 @@ func (sr *squashRuntime) initImage(ctx context.Context) (*squashImage, error) {
 		return &squashImage{}, err
 	}
 	resImage := &squashImage{
-		ClientImage: clientImage,
-		Config:      config,
-		Image:       containerImage,
-		Manifest:    manifest,
+		clientImage: clientImage,
+		config:      config,
+		image:       containerImage,
+		manifest:    manifest,
 	}
 	return resImage, err
 }
 
+// generateSquashLayer generates the squash layer based on the given options
 func (sr *squashRuntime) generateSquashLayer(image *squashImage) ([]ocispec.Descriptor, error) {
 	// get the layer descriptors by the layer digest
 	if sr.opt.SquashLayerDigest != "" {
 		find := false
 		var res []ocispec.Descriptor
-		for _, layer := range image.Manifest.Layers {
+		for _, layer := range image.manifest.Layers {
 			if layer.Digest.String() == sr.opt.SquashLayerDigest {
 				find = true
 			}
@@ -114,13 +119,14 @@ func (sr *squashRuntime) generateSquashLayer(image *squashImage) ([]ocispec.Desc
 	}
 
 	// get the layer descriptors by the layer count
-	if sr.opt.SquashLayerCount > 1 && sr.opt.SquashLayerCount <= len(image.Manifest.Layers) {
-		return image.Manifest.Layers[len(image.Manifest.Layers)-sr.opt.SquashLayerCount:], nil
+	if sr.opt.SquashLayerCount > 1 && sr.opt.SquashLayerCount <= len(image.manifest.Layers) {
+		return image.manifest.Layers[len(image.manifest.Layers)-sr.opt.SquashLayerCount:], nil
 	}
 
 	return nil, fmt.Errorf("invalid squash option: %w", errdefs.ErrInvalidArgument)
 }
 
+// applyLayersToSnapshot applies the layers to the snapshot
 func (sr *squashRuntime) applyLayersToSnapshot(ctx context.Context, mount []mount.Mount, layers []ocispec.Descriptor) error {
 	for _, layer := range layers {
 		if _, err := sr.differ.Apply(ctx, layer, mount); err != nil {
@@ -157,7 +163,7 @@ func (sr *squashRuntime) createDiff(ctx context.Context, snapshotName string) (o
 
 func (sr *squashRuntime) generateBaseImageConfig(ctx context.Context, image *squashImage, remainingLayerCount int) (ocispec.Image, error) {
 	// generate squash squashImage config
-	orginalConfig, _, err := imgutil.ReadImageConfig(ctx, image.ClientImage) // aware of img.platform
+	orginalConfig, _, err := imgutil.ReadImageConfig(ctx, image.clientImage) // aware of img.platform
 	if err != nil {
 		return ocispec.Image{}, err
 	}
@@ -257,9 +263,9 @@ func (sr *squashRuntime) writeContentsForImage(ctx context.Context, snName strin
 	return newMfstDesc, configDesc.Digest, nil
 }
 
+// createSquashImage creates a new squashImage in the image store.
 func (sr *squashRuntime) createSquashImage(ctx context.Context, img images.Image) (images.Image, error) {
 	newImg, err := sr.imageStore.Update(ctx, img)
-	log.G(ctx).Infof("updated new squashImage %s", img.Name)
 	if err != nil {
 		// if err is `not found` in the message then create the squashImage, otherwise return the error
 		if !errdefs.IsNotFound(err) {
@@ -268,13 +274,12 @@ func (sr *squashRuntime) createSquashImage(ctx context.Context, img images.Image
 		if _, err := sr.imageStore.Create(ctx, img); err != nil {
 			return newImg, fmt.Errorf("failed to create new squashImage %s: %w", img.Name, err)
 		}
-		log.G(ctx).Infof("created new squashImage %s", img.Name)
 	}
 	return newImg, nil
 }
 
 // generateCommitImageConfig returns commit oci image config based on the container's image.
-func (sr *squashRuntime) generateCommitImageConfig(ctx context.Context, baseConfig ocispec.Image, diffID digest.Digest) (ocispec.Image, error) {
+func (sr *squashRuntime) generateCommitImageConfig(ctx context.Context, baseImg images.Image, baseConfig ocispec.Image, diffID digest.Digest) (ocispec.Image, error) {
 	createdTime := time.Now()
 	arch := baseConfig.Architecture
 	if arch == "" {
@@ -292,6 +297,7 @@ func (sr *squashRuntime) generateCommitImageConfig(ctx context.Context, baseConf
 	}
 	comment := strings.TrimSpace(sr.opt.Message)
 
+	baseImageDigest := strings.Split(baseImg.Target.Digest.String(), ":")[1][:12]
 	return ocispec.Image{
 		Platform: ocispec.Platform{
 			Architecture: arch,
@@ -307,7 +313,7 @@ func (sr *squashRuntime) generateCommitImageConfig(ctx context.Context, baseConf
 		},
 		History: append(baseConfig.History, ocispec.History{
 			Created:    &createdTime,
-			CreatedBy:  "",
+			CreatedBy:  fmt.Sprintf("squash from %s", baseImageDigest),
 			Author:     author,
 			Comment:    comment,
 			EmptyLayer: false,
@@ -317,19 +323,38 @@ func (sr *squashRuntime) generateCommitImageConfig(ctx context.Context, baseConf
 
 // Squash will squash the image with the given options.
 func Squash(ctx context.Context, client *containerd.Client, option types.ImageSquashOptions) error {
+	var srcName string
+	walker := &imagewalker.ImageWalker{
+		Client: client,
+		OnFound: func(ctx context.Context, found imagewalker.Found) error {
+			if srcName == "" {
+				srcName = found.Image.Name
+			}
+			return nil
+		},
+	}
+	matchCount, err := walker.Walk(ctx, option.SourceImageRef)
+	if err != nil {
+		return err
+	}
+	if matchCount < 1 {
+		return fmt.Errorf("%s: not found", option.SourceImageRef)
+	}
+
+	option.SourceImageRef = srcName
 	sr := newSquashRuntime(client, option)
 	ctx = namespaces.WithNamespace(ctx, sr.namespace)
 	// init squashImage
-	image, err := sr.initImage(ctx)
+	img, err := sr.initImage(ctx)
 	if err != nil {
 		return err
 	}
 	// generate squash layers
-	sLayers, err := sr.generateSquashLayer(image)
+	sLayers, err := sr.generateSquashLayer(img)
 	if err != nil {
 		return err
 	}
-	remainingLayerCount := len(image.Manifest.Layers) - len(sLayers)
+	remainingLayerCount := len(img.manifest.Layers) - len(sLayers)
 	// Don't gc me and clean the dirty data after 1 hour!
 	ctx, done, err := sr.client.WithLease(ctx, leases.WithRandomID(), leases.WithExpiration(1*time.Hour))
 	if err != nil {
@@ -338,7 +363,7 @@ func Squash(ctx context.Context, client *containerd.Client, option types.ImageSq
 	defer done(ctx)
 
 	// generate remaining base squashImage config
-	baseImage, err := sr.generateBaseImageConfig(ctx, image, remainingLayerCount)
+	baseImage, err := sr.generateBaseImageConfig(ctx, img, remainingLayerCount)
 	if err != nil {
 		return err
 	}
@@ -348,27 +373,27 @@ func Squash(ctx context.Context, client *containerd.Client, option types.ImageSq
 		return err
 	}
 	// generate commit image config
-	imageConfig, err := sr.generateCommitImageConfig(ctx, baseImage, diffID)
+	imageConfig, err := sr.generateCommitImageConfig(ctx, img.image, baseImage, diffID)
 	if err != nil {
 		log.G(ctx).WithError(err).Error("failed to generate commit image config")
 		return fmt.Errorf("failed to generate commit image config: %w", err)
 	}
-	commitManifestDesc, _, err := sr.writeContentsForImage(ctx, sr.opt.GOptions.Snapshotter, imageConfig, image.Manifest.Layers[:remainingLayerCount], diffLayerDesc)
+	commitManifestDesc, _, err := sr.writeContentsForImage(ctx, sr.opt.GOptions.Snapshotter, imageConfig, img.manifest.Layers[:remainingLayerCount], diffLayerDesc)
 	if err != nil {
 		log.G(ctx).WithError(err).Error("failed to write contents for image")
 		return err
 	}
-	nimg := images.Image{
+	nImg := images.Image{
 		Name:      sr.opt.TargetImageName,
 		Target:    commitManifestDesc,
 		UpdatedAt: time.Now(),
 	}
-	_, err = sr.createSquashImage(ctx, nimg)
+	_, err = sr.createSquashImage(ctx, nImg)
 	if err != nil {
 		log.G(ctx).WithError(err).Error("failed to create squash image")
 		return err
 	}
-	cimg := containerd.NewImage(sr.client, nimg)
+	cimg := containerd.NewImage(sr.client, nImg)
 	if err := cimg.Unpack(ctx, sr.opt.GOptions.Snapshotter, containerd.WithSnapshotterPlatformCheck()); err != nil {
 		log.G(ctx).WithError(err).Error("failed to unpack squash image")
 		return err
@@ -434,6 +459,7 @@ func newSquashRuntime(client *containerd.Client, option types.ImageSquashOptions
 }
 
 // copied from github.com/containerd/containerd/rootfs/apply.go
+// which commit hash is 597d0d76ae03e945996ae6e003dae0c668fa158e by McGowan
 func uniquePart() string {
 	t := time.Now()
 	var b [3]byte