c8d/commit: Don't produce an empty layer
If the diff is empty and don't produce an empty layer. Signed-off-by: Paweł Gronowski <pawel.gronowski@docker.com>
This commit is contained in:
Paweł Gronowski
parent
a01bcf9767
commit
eb56493f4e
2 changed files with 76 additions and 32 deletions
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@ -21,6 +21,7 @@ import (
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"github.com/containerd/containerd/snapshots"
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"github.com/docker/docker/api/types/backend"
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"github.com/docker/docker/image"
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"github.com/docker/docker/pkg/archive"
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"github.com/opencontainers/go-digest"
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"github.com/opencontainers/image-spec/identity"
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"github.com/opencontainers/image-spec/specs-go"
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@ -38,28 +39,27 @@ func (i *ImageService) CommitImage(ctx context.Context, cc backend.CommitConfig)
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container := i.containers.Get(cc.ContainerID)
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cs := i.client.ContentStore()
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imageManifest, err := getContainerImageManifest(container)
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if err != nil {
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return "", err
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}
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var parentManifest ocispec.Manifest
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var parentImage ocispec.Image
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imageManifestBytes, err := content.ReadBlob(ctx, cs, imageManifest)
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if err != nil {
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return "", err
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}
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// ImageManifest can be nil when committing an image with base FROM scratch
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if container.ImageManifest != nil {
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imageManifestBytes, err := content.ReadBlob(ctx, cs, *container.ImageManifest)
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if err != nil {
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return "", err
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}
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var manifest ocispec.Manifest
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if err := json.Unmarshal(imageManifestBytes, &manifest); err != nil {
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return "", err
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}
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if err := json.Unmarshal(imageManifestBytes, &parentManifest); err != nil {
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return "", err
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}
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imageConfigBytes, err := content.ReadBlob(ctx, cs, manifest.Config)
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if err != nil {
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return "", err
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}
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var ociimage ocispec.Image
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if err := json.Unmarshal(imageConfigBytes, &ociimage); err != nil {
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return "", err
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imageConfigBytes, err := content.ReadBlob(ctx, cs, parentManifest.Config)
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if err != nil {
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return "", err
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}
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if err := json.Unmarshal(imageConfigBytes, &parentImage); err != nil {
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return "", err
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}
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}
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var (
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@ -78,15 +78,19 @@ func (i *ImageService) CommitImage(ctx context.Context, cc backend.CommitConfig)
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if err != nil {
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return "", fmt.Errorf("failed to export layer: %w", err)
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}
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imageConfig := generateCommitImageConfig(parentImage, diffID, cc)
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imageConfig := generateCommitImageConfig(ociimage, diffID, cc)
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layers := parentManifest.Layers
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if diffLayerDesc != nil {
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rootfsID := identity.ChainID(imageConfig.RootFS.DiffIDs).String()
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rootfsID := identity.ChainID(imageConfig.RootFS.DiffIDs).String()
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if err := applyDiffLayer(ctx, rootfsID, ociimage, sn, differ, diffLayerDesc); err != nil {
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return "", fmt.Errorf("failed to apply diff: %w", err)
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if err := applyDiffLayer(ctx, rootfsID, parentImage, sn, differ, *diffLayerDesc); err != nil {
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return "", fmt.Errorf("failed to apply diff: %w", err)
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}
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layers = append(layers, *diffLayerDesc)
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}
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layers := append(manifest.Layers, diffLayerDesc)
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commitManifestDesc, err := writeContentsForImage(ctx, container.Driver, cs, imageConfig, layers)
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if err != nil {
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return "", err
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@ -130,6 +134,12 @@ func generateCommitImageConfig(baseConfig ocispec.Image, diffID digest.Digest, o
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log.G(context.TODO()).Warnf("assuming os=%q", os)
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}
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log.G(context.TODO()).Debugf("generateCommitImageConfig(): arch=%q, os=%q", arch, os)
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diffIds := baseConfig.RootFS.DiffIDs
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if diffID != "" {
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diffIds = append(diffIds, diffID)
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}
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return ocispec.Image{
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Platform: ocispec.Platform{
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Architecture: arch,
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@ -140,7 +150,7 @@ func generateCommitImageConfig(baseConfig ocispec.Image, diffID digest.Digest, o
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Config: containerConfigToOciImageConfig(opts.Config),
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RootFS: ocispec.RootFS{
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Type: "layers",
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DiffIDs: append(baseConfig.RootFS.DiffIDs, diffID),
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DiffIDs: diffIds,
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},
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History: append(baseConfig.History, ocispec.History{
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Created: &createdTime,
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@ -217,28 +227,43 @@ func writeContentsForImage(ctx context.Context, snName string, cs content.Store,
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}
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// createDiff creates a layer diff into containerd's content store.
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func createDiff(ctx context.Context, name string, sn snapshots.Snapshotter, cs content.Store, comparer diff.Comparer) (ocispec.Descriptor, digest.Digest, error) {
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// If the diff is empty it returns nil empty digest and no error.
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func createDiff(ctx context.Context, name string, sn snapshots.Snapshotter, cs content.Store, comparer diff.Comparer) (*ocispec.Descriptor, digest.Digest, error) {
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newDesc, err := rootfs.CreateDiff(ctx, name, sn, comparer)
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if err != nil {
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return ocispec.Descriptor{}, "", err
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return nil, "", err
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}
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ra, err := cs.ReaderAt(ctx, newDesc)
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if err != nil {
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return nil, "", fmt.Errorf("failed to read diff archive: %w", err)
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}
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defer ra.Close()
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empty, err := archive.IsEmpty(content.NewReader(ra))
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if err != nil {
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return nil, "", fmt.Errorf("failed to check if archive is empty: %w", err)
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}
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if empty {
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return nil, "", nil
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}
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info, err := cs.Info(ctx, newDesc.Digest)
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if err != nil {
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return ocispec.Descriptor{}, "", err
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return nil, "", fmt.Errorf("failed to get content info: %w", err)
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}
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diffIDStr, ok := info.Labels["containerd.io/uncompressed"]
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if !ok {
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return ocispec.Descriptor{}, "", fmt.Errorf("invalid differ response with no diffID")
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return nil, "", fmt.Errorf("invalid differ response with no diffID")
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}
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diffID, err := digest.Parse(diffIDStr)
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if err != nil {
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return ocispec.Descriptor{}, "", err
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return nil, "", err
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}
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return ocispec.Descriptor{
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return &ocispec.Descriptor{
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MediaType: ocispec.MediaTypeImageLayerGzip,
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Digest: newDesc.Digest,
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Size: info.Size,
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@ -254,7 +279,7 @@ func applyDiffLayer(ctx context.Context, name string, baseImg ocispec.Image, sn
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mount, err := sn.Prepare(ctx, key, parent)
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if err != nil {
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return err
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return fmt.Errorf("failed to prepare snapshot: %w", err)
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}
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defer func() {
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@ -224,6 +224,25 @@ func ApplyUncompressedLayer(dest string, layer io.Reader, options *TarOptions) (
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return applyLayerHandler(dest, layer, options, false)
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}
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// IsEmpty checks if the tar archive is empty (doesn't contain any entries).
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func IsEmpty(rd io.Reader) (bool, error) {
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decompRd, err := DecompressStream(rd)
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if err != nil {
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return true, fmt.Errorf("failed to decompress archive: %v", err)
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}
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defer decompRd.Close()
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tarReader := tar.NewReader(decompRd)
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if _, err := tarReader.Next(); err != nil {
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if err == io.EOF {
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return true, nil
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}
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return false, fmt.Errorf("failed to read next archive header: %v", err)
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}
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return false, nil
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}
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// do the bulk load of ApplyLayer, but allow for not calling DecompressStream
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func applyLayerHandler(dest string, layer io.Reader, options *TarOptions, decompress bool) (int64, error) {
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dest = filepath.Clean(dest)
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