99 lines
2.5 KiB
Go
99 lines
2.5 KiB
Go
package blobs
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import (
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gocontext "context"
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"github.com/containerd/containerd/mount"
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"github.com/containerd/containerd/rootfs"
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"github.com/moby/buildkit/cache"
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"github.com/moby/buildkit/snapshot"
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"github.com/moby/buildkit/util/flightcontrol"
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digest "github.com/opencontainers/go-digest"
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ocispec "github.com/opencontainers/image-spec/specs-go/v1"
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"github.com/pkg/errors"
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"golang.org/x/net/context"
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"golang.org/x/sync/errgroup"
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)
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var g flightcontrol.Group
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type DiffPair struct {
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DiffID digest.Digest
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Blobsum digest.Digest
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}
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type blobmapper interface {
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GetBlob(ctx gocontext.Context, key string) (digest.Digest, error)
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SetBlob(ctx gocontext.Context, key string, blob digest.Digest) error
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}
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func GetDiffPairs(ctx context.Context, snapshotter snapshot.Snapshotter, differ rootfs.MountDiffer, ref cache.ImmutableRef) ([]DiffPair, error) {
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blobmap, ok := snapshotter.(blobmapper)
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if !ok {
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return nil, errors.Errorf("image exporter requires snapshotter with blobs mapping support")
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}
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eg, ctx := errgroup.WithContext(ctx)
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var diffPairs []DiffPair
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var currentPair DiffPair
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parent := ref.Parent()
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if parent != nil {
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defer parent.Release(context.TODO())
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eg.Go(func() error {
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dp, err := GetDiffPairs(ctx, snapshotter, differ, parent)
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if err != nil {
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return err
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}
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diffPairs = dp
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return nil
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})
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}
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eg.Go(func() error {
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dp, err := g.Do(ctx, ref.ID(), func(ctx context.Context) (interface{}, error) {
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blob, err := blobmap.GetBlob(ctx, ref.ID())
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if err != nil {
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return nil, err
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}
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if blob != "" {
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diffID, err := digest.Parse(ref.ID())
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if err != nil {
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diffID = blob
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}
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return DiffPair{DiffID: diffID, Blobsum: blob}, nil
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}
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// reference needs to be committed
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parent := ref.Parent()
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var lower []mount.Mount
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if parent != nil {
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defer parent.Release(context.TODO())
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lower, err = parent.Mount(ctx, true)
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if err != nil {
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return nil, err
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}
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}
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upper, err := ref.Mount(ctx, true)
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if err != nil {
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return nil, err
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}
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descr, err := differ.DiffMounts(ctx, lower, upper, ocispec.MediaTypeImageLayer, ref.ID())
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if err != nil {
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return nil, err
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}
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if err := blobmap.SetBlob(ctx, ref.ID(), descr.Digest); err != nil {
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return nil, err
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}
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return DiffPair{DiffID: descr.Digest, Blobsum: descr.Digest}, nil
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})
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if err != nil {
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return err
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}
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currentPair = dp.(DiffPair)
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return nil
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})
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err := eg.Wait()
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if err != nil {
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return nil, err
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}
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return append(diffPairs, currentPair), nil
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}
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