131 lines
3.4 KiB
Go
131 lines
3.4 KiB
Go
package containerd
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import (
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"context"
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"encoding/json"
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"github.com/containerd/containerd/content"
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"github.com/containerd/containerd/images"
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"github.com/containerd/containerd/rootfs"
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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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)
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// Image describes an image used by containers
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type Image interface {
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// Name of the image
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Name() string
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// Target descriptor for the image content
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Target() ocispec.Descriptor
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// Unpack unpacks the image's content into a snapshot
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Unpack(context.Context, string) error
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// RootFS returns the unpacked diffids that make up images rootfs.
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RootFS(ctx context.Context) ([]digest.Digest, error)
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// Size returns the total size of the image's packed resources.
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Size(ctx context.Context) (int64, error)
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// Config descriptor for the image.
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Config(ctx context.Context) (ocispec.Descriptor, error)
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}
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var _ = (Image)(&image{})
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type image struct {
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client *Client
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i images.Image
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}
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func (i *image) Name() string {
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return i.i.Name
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}
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func (i *image) Target() ocispec.Descriptor {
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return i.i.Target
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}
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func (i *image) RootFS(ctx context.Context) ([]digest.Digest, error) {
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provider := i.client.ContentStore()
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return i.i.RootFS(ctx, provider)
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}
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func (i *image) Size(ctx context.Context) (int64, error) {
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provider := i.client.ContentStore()
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return i.i.Size(ctx, provider)
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}
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func (i *image) Config(ctx context.Context) (ocispec.Descriptor, error) {
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provider := i.client.ContentStore()
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return i.i.Config(ctx, provider)
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}
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func (i *image) Unpack(ctx context.Context, snapshotterName string) error {
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layers, err := i.getLayers(ctx)
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if err != nil {
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return err
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}
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sn := i.client.SnapshotService(snapshotterName)
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a := i.client.DiffService()
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cs := i.client.ContentStore()
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var chain []digest.Digest
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for _, layer := range layers {
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unpacked, err := rootfs.ApplyLayer(ctx, layer, chain, sn, a)
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if err != nil {
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// TODO: possibly wait and retry if extraction of same chain id was in progress
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return err
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}
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if unpacked {
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info, err := cs.Info(ctx, layer.Blob.Digest)
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if err != nil {
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return err
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}
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if info.Labels["containerd.io/uncompressed"] != layer.Diff.Digest.String() {
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if info.Labels == nil {
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info.Labels = map[string]string{}
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}
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info.Labels["containerd.io/uncompressed"] = layer.Diff.Digest.String()
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if _, err := cs.Update(ctx, info, "labels.containerd.io/uncompressed"); err != nil {
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return err
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}
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}
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}
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chain = append(chain, layer.Diff.Digest)
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}
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return nil
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}
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func (i *image) getLayers(ctx context.Context) ([]rootfs.Layer, error) {
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cs := i.client.ContentStore()
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// TODO: Support manifest list
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p, err := content.ReadBlob(ctx, cs, i.i.Target.Digest)
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if err != nil {
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return nil, errors.Wrapf(err, "failed to read manifest blob")
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}
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var manifest ocispec.Manifest
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if err := json.Unmarshal(p, &manifest); err != nil {
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return nil, errors.Wrap(err, "failed to unmarshal manifest")
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}
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diffIDs, err := i.i.RootFS(ctx, cs)
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if err != nil {
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return nil, errors.Wrap(err, "failed to resolve rootfs")
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}
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if len(diffIDs) != len(manifest.Layers) {
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return nil, errors.Errorf("mismatched image rootfs and manifest layers")
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}
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layers := make([]rootfs.Layer, len(diffIDs))
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for i := range diffIDs {
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layers[i].Diff = ocispec.Descriptor{
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// TODO: derive media type from compressed type
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MediaType: ocispec.MediaTypeImageLayer,
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Digest: diffIDs[i],
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}
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layers[i].Blob = manifest.Layers[i]
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}
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return layers, nil
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}
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