libimage/copier: wire ForceCompressionFormat for image copy

Implement containers/image#2068 for
libimage/copier.

Signed-off-by: Aditya R <[email protected]>

libimage/copier.go

@@ -49,6 +49,10 @@ type CopyOptions struct {
 	CompressionFormat *compression.Algorithm
 	// CompressionLevel specifies what compression level is used
 	CompressionLevel *int
+	// ForceCompressionFormat ensures that the compression algorithm set in
+	// CompressionFormat is used exclusively, and blobs of other compression
+	// algorithms are not reused.
+	ForceCompressionFormat bool
 
 	// containers-auth.json(5) file to use when authenticating against
 	// container registries.
@@ -294,6 +298,7 @@ func (r *Runtime) newCopier(options *CopyOptions) (*copier, error) {
 		c.imageCopyOptions.ProgressInterval = time.Second
 	}
 
+	c.imageCopyOptions.ForceCompressionFormat = options.ForceCompressionFormat
 	c.imageCopyOptions.ForceManifestMIMEType = options.ManifestMIMEType
 	c.imageCopyOptions.SourceCtx = c.systemContext
 	c.imageCopyOptions.DestinationCtx = c.systemContext

libimage/push_test.go

@@ -3,9 +3,12 @@ package libimage
 import (
 	"context"
 	"os"
+	"path/filepath"
 	"testing"
 
 	"github.com/containers/common/pkg/config"
+	"github.com/containers/image/v5/pkg/compression"
+	"github.com/stretchr/testify/assert"
 	"github.com/stretchr/testify/require"
 )
 
@@ -96,3 +99,70 @@ func TestPushOtherPlatform(t *testing.T) {
 	_, err = runtime.Push(ctx, "docker.io/library/alpine:latest", "docker-archive:"+tmp.Name(), pushOptions)
 	require.NoError(t, err)
 }
+
+func TestPushWithForceCompression(t *testing.T) {
+	runtime, cleanup := testNewRuntime(t)
+	defer cleanup()
+	ctx := context.Background()
+
+	// Prefetch alpine.
+	pullOptions := &PullOptions{}
+	pullOptions.Writer = os.Stdout
+	pullOptions.Architecture = "arm64"
+	pulledImages, err := runtime.Pull(ctx, "docker.io/library/alpine:latest", config.PullPolicyAlways, pullOptions)
+	require.NoError(t, err)
+	require.Len(t, pulledImages, 1)
+
+	data, err := pulledImages[0].Inspect(ctx, nil)
+	require.NoError(t, err)
+	require.Equal(t, "arm64", data.Architecture)
+
+	pushOptions := &PushOptions{}
+	pushOptions.CompressionFormat = &compression.Zstd
+	pushOptions.Writer = os.Stdout
+	tmp := t.TempDir()
+	_, err = runtime.Push(ctx, "docker.io/library/alpine:latest", "oci:"+tmp, pushOptions)
+	require.NoError(t, err)
+
+	// blobs from first push
+	entries, err := os.ReadDir(filepath.Join(tmp, "blobs", "sha256"))
+	require.NoError(t, err)
+	blobsFirstPush := []string{}
+	for _, e := range entries {
+		blobsFirstPush = append(blobsFirstPush, e.Name())
+	}
+
+	_, err = runtime.Push(ctx, "docker.io/library/alpine:latest", "oci:"+tmp, pushOptions)
+	require.NoError(t, err)
+
+	// blobs from second push
+	entries, err = os.ReadDir(filepath.Join(tmp, "blobs", "sha256"))
+	require.NoError(t, err)
+	blobsSecondPush := []string{}
+	for _, e := range entries {
+		blobsSecondPush = append(blobsSecondPush, e.Name())
+	}
+
+	// All blobs of first push should be equivalent to blobs of
+	// second push since same compression was used
+	assert.Equal(t, blobsSecondPush, blobsFirstPush)
+
+	pushOptions = &PushOptions{}
+	pushOptions.CompressionFormat = &compression.Gzip
+	pushOptions.ForceCompressionFormat = true
+	pushOptions.Writer = os.Stdout
+
+	_, err = runtime.Push(ctx, "docker.io/library/alpine:latest", "oci:"+tmp, pushOptions)
+	require.NoError(t, err)
+
+	entries, err = os.ReadDir(filepath.Join(tmp, "blobs", "sha256"))
+	require.NoError(t, err)
+	blobsThirdPush := []string{}
+	for _, e := range entries {
+		blobsThirdPush = append(blobsThirdPush, e.Name())
+	}
+	// Blobs of third push should not be equivalent to blobs of
+	// second and first push since different compression was used
+	// and ForceCompressionFormat is `true`
+	assert.NotEqual(t, blobsThirdPush, blobsFirstPush)
+}