package images import ( "context" "encoding/json" "errors" "io/ioutil" "github.com/containerd/containerd/content" "github.com/containerd/containerd/log" digest "github.com/opencontainers/go-digest" ocispec "github.com/opencontainers/image-spec/specs-go/v1" ) // Image provides the model for how containerd views container images. type Image struct { Name string Target ocispec.Descriptor } // TODO(stevvooe): Many of these functions make strong platform assumptions, // which are untrue in a lot of cases. More refactoring must be done here to // make this work in all cases. // Config resolves the image configuration descriptor. // // The caller can then use the descriptor to resolve and process the // configuration of the image. func (image *Image) Config(ctx context.Context, provider content.Provider) (ocispec.Descriptor, error) { var configDesc ocispec.Descriptor return configDesc, Walk(ctx, HandlerFunc(func(ctx context.Context, desc ocispec.Descriptor) ([]ocispec.Descriptor, error) { switch image.Target.MediaType { case MediaTypeDockerSchema2Manifest, ocispec.MediaTypeImageManifest: rc, err := provider.Reader(ctx, image.Target.Digest) if err != nil { return nil, err } defer rc.Close() p, err := ioutil.ReadAll(rc) if err != nil { return nil, err } var manifest ocispec.Manifest if err := json.Unmarshal(p, &manifest); err != nil { return nil, err } configDesc = manifest.Config return nil, nil default: return nil, errors.New("could not resolve config") } }), image.Target) } // RootFS returns the unpacked diffids that make up and images rootfs. // // These are used to verify that a set of layers unpacked to the expected // values. func (image *Image) RootFS(ctx context.Context, provider content.Provider) ([]digest.Digest, error) { desc, err := image.Config(ctx, provider) if err != nil { return nil, err } p, err := content.ReadBlob(ctx, provider, desc.Digest) if err != nil { log.G(ctx).Fatal(err) } var config ocispec.Image if err := json.Unmarshal(p, &config); err != nil { log.G(ctx).Fatal(err) } // TODO(stevvooe): Remove this bit when OCI structure uses correct type for // rootfs.DiffIDs. var diffIDs []digest.Digest for _, diffID := range config.RootFS.DiffIDs { diffIDs = append(diffIDs, digest.Digest(diffID)) } return diffIDs, nil } // Size returns the total size of an image's packed resources. func (image *Image) Size(ctx context.Context, provider content.Provider) (int64, error) { var size int64 return size, Walk(ctx, HandlerFunc(func(ctx context.Context, desc ocispec.Descriptor) ([]ocispec.Descriptor, error) { switch image.Target.MediaType { case MediaTypeDockerSchema2Manifest, ocispec.MediaTypeImageManifest: size += desc.Size rc, err := provider.Reader(ctx, image.Target.Digest) if err != nil { return nil, err } defer rc.Close() p, err := ioutil.ReadAll(rc) if err != nil { return nil, err } var manifest ocispec.Manifest if err := json.Unmarshal(p, &manifest); err != nil { return nil, err } size += manifest.Config.Size for _, layer := range manifest.Layers { size += layer.Size } return nil, nil default: return nil, errors.New("unsupported type") } }), image.Target) }