package buildah import ( "bytes" "context" "encoding/json" "fmt" "io" "io/ioutil" "os" "path/filepath" "time" "github.com/containers/image/docker/reference" "github.com/containers/image/image" is "github.com/containers/image/storage" "github.com/containers/image/types" "github.com/containers/storage" "github.com/containers/storage/pkg/archive" "github.com/containers/storage/pkg/ioutils" digest "github.com/opencontainers/go-digest" specs "github.com/opencontainers/image-spec/specs-go" "github.com/opencontainers/image-spec/specs-go/v1" "github.com/pkg/errors" "github.com/projectatomic/buildah/docker" "github.com/sirupsen/logrus" ) const ( // OCIv1ImageManifest is the MIME type of an OCIv1 image manifest, // suitable for specifying as a value of the PreferredManifestType // member of a CommitOptions structure. It is also the default. OCIv1ImageManifest = v1.MediaTypeImageManifest // Dockerv2ImageManifest is the MIME type of a Docker v2s2 image // manifest, suitable for specifying as a value of the // PreferredManifestType member of a CommitOptions structure. Dockerv2ImageManifest = docker.V2S2MediaTypeManifest ) type containerImageRef struct { store storage.Store compression archive.Compression name reference.Named names []string containerID string mountLabel string layerID string oconfig []byte dconfig []byte created time.Time createdBy string historyComment string annotations map[string]string preferredManifestType string exporting bool squash bool tarPath func(path string) (io.ReadCloser, error) parent string } type containerImageSource struct { path string ref *containerImageRef store storage.Store containerID string mountLabel string layerID string names []string compression archive.Compression config []byte configDigest digest.Digest manifest []byte manifestType string exporting bool } func (i *containerImageRef) NewImage(ctx context.Context, sc *types.SystemContext) (types.ImageCloser, error) { src, err := i.NewImageSource(ctx, sc) if err != nil { return nil, err } return image.FromSource(ctx, sc, src) } func expectedOCIDiffIDs(image v1.Image) int { expected := 0 for _, history := range image.History { if !history.EmptyLayer { expected = expected + 1 } } return expected } func expectedDockerDiffIDs(image docker.V2Image) int { expected := 0 for _, history := range image.History { if !history.EmptyLayer { expected = expected + 1 } } return expected } // Compute the media types which we need to attach to a layer, given the type of // compression that we'll be applying. func (i *containerImageRef) computeLayerMIMEType(what string) (omediaType, dmediaType string, err error) { omediaType = v1.MediaTypeImageLayer dmediaType = docker.V2S2MediaTypeUncompressedLayer if i.compression != archive.Uncompressed { switch i.compression { case archive.Gzip: omediaType = v1.MediaTypeImageLayerGzip dmediaType = docker.V2S2MediaTypeLayer logrus.Debugf("compressing %s with gzip", what) case archive.Bzip2: // Until the image specs define a media type for bzip2-compressed layers, even if we know // how to decompress them, we can't try to compress layers with bzip2. return "", "", errors.New("media type for bzip2-compressed layers is not defined") case archive.Xz: // Until the image specs define a media type for xz-compressed layers, even if we know // how to decompress them, we can't try to compress layers with xz. return "", "", errors.New("media type for xz-compressed layers is not defined") default: logrus.Debugf("compressing %s with unknown compressor(?)", what) } } return omediaType, dmediaType, nil } // Extract the container's whole filesystem as if it were a single layer. func (i *containerImageRef) extractRootfs() (io.ReadCloser, error) { mountPoint, err := i.store.Mount(i.containerID, i.mountLabel) if err != nil { return nil, errors.Wrapf(err, "error extracting container %q", i.containerID) } rc, err := i.tarPath(mountPoint) if err != nil { return nil, errors.Wrapf(err, "error extracting container %q", i.containerID) } return ioutils.NewReadCloserWrapper(rc, func() error { err := rc.Close() if err != nil { err = errors.Wrapf(err, "error closing tar archive of container %q", i.containerID) } if err2 := i.store.Unmount(i.containerID); err == nil { if err2 != nil { err2 = errors.Wrapf(err2, "error unmounting container %q", i.containerID) } err = err2 } return err }), nil } // Build fresh copies of the container configuration structures so that we can edit them // without making unintended changes to the original Builder. func (i *containerImageRef) createConfigsAndManifests() (v1.Image, v1.Manifest, docker.V2Image, docker.V2S2Manifest, error) { created := i.created // Build an empty image, and then decode over it. oimage := v1.Image{} if err := json.Unmarshal(i.oconfig, &oimage); err != nil { return v1.Image{}, v1.Manifest{}, docker.V2Image{}, docker.V2S2Manifest{}, err } // Always replace this value, since we're newer than our base image. oimage.Created = &created // Clear the list of diffIDs, since we always repopulate it. oimage.RootFS.Type = docker.TypeLayers oimage.RootFS.DiffIDs = []digest.Digest{} // Only clear the history if we're squashing, otherwise leave it be so that we can append // entries to it. if i.squash { oimage.History = []v1.History{} } // Build an empty image, and then decode over it. dimage := docker.V2Image{} if err := json.Unmarshal(i.dconfig, &dimage); err != nil { return v1.Image{}, v1.Manifest{}, docker.V2Image{}, docker.V2S2Manifest{}, err } dimage.Parent = docker.ID(digest.FromString(i.parent)) // Always replace this value, since we're newer than our base image. dimage.Created = created // Clear the list of diffIDs, since we always repopulate it. dimage.RootFS = &docker.V2S2RootFS{} dimage.RootFS.Type = docker.TypeLayers dimage.RootFS.DiffIDs = []digest.Digest{} // Only clear the history if we're squashing, otherwise leave it be so that we can append // entries to it. if i.squash { dimage.History = []docker.V2S2History{} } // Build empty manifests. The Layers lists will be populated later. omanifest := v1.Manifest{ Versioned: specs.Versioned{ SchemaVersion: 2, }, Config: v1.Descriptor{ MediaType: v1.MediaTypeImageConfig, }, Layers: []v1.Descriptor{}, Annotations: i.annotations, } dmanifest := docker.V2S2Manifest{ V2Versioned: docker.V2Versioned{ SchemaVersion: 2, MediaType: docker.V2S2MediaTypeManifest, }, Config: docker.V2S2Descriptor{ MediaType: docker.V2S2MediaTypeImageConfig, }, Layers: []docker.V2S2Descriptor{}, } return oimage, omanifest, dimage, dmanifest, nil } func (i *containerImageRef) NewImageSource(ctx context.Context, sc *types.SystemContext) (src types.ImageSource, err error) { // Decide which type of manifest and configuration output we're going to provide. manifestType := i.preferredManifestType // If it's not a format we support, return an error. if manifestType != v1.MediaTypeImageManifest && manifestType != docker.V2S2MediaTypeManifest { return nil, errors.Errorf("no supported manifest types (attempted to use %q, only know %q and %q)", manifestType, v1.MediaTypeImageManifest, docker.V2S2MediaTypeManifest) } // Start building the list of layers using the read-write layer. layers := []string{} layerID := i.layerID layer, err := i.store.Layer(layerID) if err != nil { return nil, errors.Wrapf(err, "unable to read layer %q", layerID) } // Walk the list of parent layers, prepending each as we go. If we're squashing, // stop at the layer ID of the top layer, which we won't really be using anyway. for layer != nil { layers = append(append([]string{}, layerID), layers...) layerID = layer.Parent if layerID == "" || i.squash { err = nil break } layer, err = i.store.Layer(layerID) if err != nil { return nil, errors.Wrapf(err, "unable to read layer %q", layerID) } } logrus.Debugf("layer list: %q", layers) // Make a temporary directory to hold blobs. path, err := ioutil.TempDir(os.TempDir(), Package) if err != nil { return nil, err } logrus.Debugf("using %q to hold temporary data", path) defer func() { if src == nil { err2 := os.RemoveAll(path) if err2 != nil { logrus.Errorf("error removing %q: %v", path, err) } } }() // Build fresh copies of the configurations and manifest so that we don't mess with any // values in the Builder object itself. oimage, omanifest, dimage, dmanifest, err := i.createConfigsAndManifests() if err != nil { return nil, err } // Extract each layer and compute its digests, both compressed (if requested) and uncompressed. for _, layerID := range layers { what := fmt.Sprintf("layer %q", layerID) if i.squash { what = fmt.Sprintf("container %q", i.containerID) } // The default layer media type assumes no compression. omediaType := v1.MediaTypeImageLayer dmediaType := docker.V2S2MediaTypeUncompressedLayer // If we're not re-exporting the data, and we're reusing layers individually, reuse // the blobsum and diff IDs. if !i.exporting && !i.squash && layerID != i.layerID { layer, err2 := i.store.Layer(layerID) if err2 != nil { return nil, errors.Wrapf(err, "unable to locate layer %q", layerID) } if layer.UncompressedDigest == "" { return nil, errors.Errorf("unable to look up size of layer %q", layerID) } layerBlobSum := layer.UncompressedDigest layerBlobSize := layer.UncompressedSize // Note this layer in the manifest, using the uncompressed blobsum. olayerDescriptor := v1.Descriptor{ MediaType: omediaType, Digest: layerBlobSum, Size: layerBlobSize, } omanifest.Layers = append(omanifest.Layers, olayerDescriptor) dlayerDescriptor := docker.V2S2Descriptor{ MediaType: dmediaType, Digest: layerBlobSum, Size: layerBlobSize, } dmanifest.Layers = append(dmanifest.Layers, dlayerDescriptor) // Note this layer in the list of diffIDs, again using the uncompressed blobsum. oimage.RootFS.DiffIDs = append(oimage.RootFS.DiffIDs, layerBlobSum) dimage.RootFS.DiffIDs = append(dimage.RootFS.DiffIDs, layerBlobSum) continue } // Figure out if we need to change the media type, in case we're using compression. omediaType, dmediaType, err = i.computeLayerMIMEType(what) if err != nil { return nil, err } // Start reading either the layer or the whole container rootfs. noCompression := archive.Uncompressed diffOptions := &storage.DiffOptions{ Compression: &noCompression, } var rc io.ReadCloser if i.squash { // Extract the root filesystem as a single layer. rc, err = i.extractRootfs() if err != nil { return nil, err } defer rc.Close() } else { // Extract this layer, one of possibly many. rc, err = i.store.Diff("", layerID, diffOptions) if err != nil { return nil, errors.Wrapf(err, "error extracting %s", what) } defer rc.Close() } srcHasher := digest.Canonical.Digester() reader := io.TeeReader(rc, srcHasher.Hash()) // Set up to write the possibly-recompressed blob. layerFile, err := os.OpenFile(filepath.Join(path, "layer"), os.O_CREATE|os.O_WRONLY, 0600) if err != nil { return nil, errors.Wrapf(err, "error opening file for %s", what) } destHasher := digest.Canonical.Digester() counter := ioutils.NewWriteCounter(layerFile) multiWriter := io.MultiWriter(counter, destHasher.Hash()) // Compress the layer, if we're recompressing it. writer, err := archive.CompressStream(multiWriter, i.compression) if err != nil { return nil, errors.Wrapf(err, "error compressing %s", what) } size, err := io.Copy(writer, reader) if err != nil { return nil, errors.Wrapf(err, "error storing %s to file", what) } writer.Close() layerFile.Close() if i.compression == archive.Uncompressed { if size != counter.Count { return nil, errors.Errorf("error storing %s to file: inconsistent layer size (copied %d, wrote %d)", what, size, counter.Count) } } else { size = counter.Count } logrus.Debugf("%s size is %d bytes", what, size) // Rename the layer so that we can more easily find it by digest later. err = os.Rename(filepath.Join(path, "layer"), filepath.Join(path, destHasher.Digest().String())) if err != nil { return nil, errors.Wrapf(err, "error storing %s to file", what) } // Add a note in the manifest about the layer. The blobs are identified by their possibly- // compressed blob digests. olayerDescriptor := v1.Descriptor{ MediaType: omediaType, Digest: destHasher.Digest(), Size: size, } omanifest.Layers = append(omanifest.Layers, olayerDescriptor) dlayerDescriptor := docker.V2S2Descriptor{ MediaType: dmediaType, Digest: destHasher.Digest(), Size: size, } dmanifest.Layers = append(dmanifest.Layers, dlayerDescriptor) // Add a note about the diffID, which is always the layer's uncompressed digest. oimage.RootFS.DiffIDs = append(oimage.RootFS.DiffIDs, srcHasher.Digest()) dimage.RootFS.DiffIDs = append(dimage.RootFS.DiffIDs, srcHasher.Digest()) } // Build history notes in the image configurations. onews := v1.History{ Created: &i.created, CreatedBy: i.createdBy, Author: oimage.Author, Comment: i.historyComment, EmptyLayer: false, } oimage.History = append(oimage.History, onews) dnews := docker.V2S2History{ Created: i.created, CreatedBy: i.createdBy, Author: dimage.Author, Comment: i.historyComment, EmptyLayer: false, } dimage.History = append(dimage.History, dnews) dimage.Parent = docker.ID(digest.FromString(i.parent)) // Sanity check that we didn't just create a mismatch between non-empty layers in the // history and the number of diffIDs. expectedDiffIDs := expectedOCIDiffIDs(oimage) if len(oimage.RootFS.DiffIDs) != expectedDiffIDs { return nil, errors.Errorf("internal error: history lists %d non-empty layers, but we have %d layers on disk", expectedDiffIDs, len(oimage.RootFS.DiffIDs)) } expectedDiffIDs = expectedDockerDiffIDs(dimage) if len(dimage.RootFS.DiffIDs) != expectedDiffIDs { return nil, errors.Errorf("internal error: history lists %d non-empty layers, but we have %d layers on disk", expectedDiffIDs, len(dimage.RootFS.DiffIDs)) } // Encode the image configuration blob. oconfig, err := json.Marshal(&oimage) if err != nil { return nil, err } logrus.Debugf("OCIv1 config = %s", oconfig) // Add the configuration blob to the manifest. omanifest.Config.Digest = digest.Canonical.FromBytes(oconfig) omanifest.Config.Size = int64(len(oconfig)) omanifest.Config.MediaType = v1.MediaTypeImageConfig // Encode the manifest. omanifestbytes, err := json.Marshal(&omanifest) if err != nil { return nil, err } logrus.Debugf("OCIv1 manifest = %s", omanifestbytes) // Encode the image configuration blob. dconfig, err := json.Marshal(&dimage) if err != nil { return nil, err } logrus.Debugf("Docker v2s2 config = %s", dconfig) // Add the configuration blob to the manifest. dmanifest.Config.Digest = digest.Canonical.FromBytes(dconfig) dmanifest.Config.Size = int64(len(dconfig)) dmanifest.Config.MediaType = docker.V2S2MediaTypeImageConfig // Encode the manifest. dmanifestbytes, err := json.Marshal(&dmanifest) if err != nil { return nil, err } logrus.Debugf("Docker v2s2 manifest = %s", dmanifestbytes) // Decide which manifest and configuration blobs we'll actually output. var config []byte var manifest []byte switch manifestType { case v1.MediaTypeImageManifest: manifest = omanifestbytes config = oconfig case docker.V2S2MediaTypeManifest: manifest = dmanifestbytes config = dconfig default: panic("unreachable code: unsupported manifest type") } src = &containerImageSource{ path: path, ref: i, store: i.store, containerID: i.containerID, mountLabel: i.mountLabel, layerID: i.layerID, names: i.names, compression: i.compression, config: config, configDigest: digest.Canonical.FromBytes(config), manifest: manifest, manifestType: manifestType, exporting: i.exporting, } return src, nil } func (i *containerImageRef) NewImageDestination(ctx context.Context, sc *types.SystemContext) (types.ImageDestination, error) { return nil, errors.Errorf("can't write to a container") } func (i *containerImageRef) DockerReference() reference.Named { return i.name } func (i *containerImageRef) StringWithinTransport() string { if len(i.names) > 0 { return i.names[0] } return "" } func (i *containerImageRef) DeleteImage(context.Context, *types.SystemContext) error { // we were never here return nil } func (i *containerImageRef) PolicyConfigurationIdentity() string { return "" } func (i *containerImageRef) PolicyConfigurationNamespaces() []string { return nil } func (i *containerImageRef) Transport() types.ImageTransport { return is.Transport } func (i *containerImageSource) Close() error { err := os.RemoveAll(i.path) if err != nil { logrus.Errorf("error removing %q: %v", i.path, err) } return err } func (i *containerImageSource) Reference() types.ImageReference { return i.ref } func (i *containerImageSource) GetSignatures(ctx context.Context, instanceDigest *digest.Digest) ([][]byte, error) { if instanceDigest != nil { return nil, errors.Errorf("containerImageSource does not support manifest lists") } return nil, nil } func (i *containerImageSource) GetManifest(ctx context.Context, instanceDigest *digest.Digest) ([]byte, string, error) { if instanceDigest != nil { return nil, "", errors.Errorf("containerImageSource does not support manifest lists") } return i.manifest, i.manifestType, nil } func (i *containerImageSource) LayerInfosForCopy(ctx context.Context) ([]types.BlobInfo, error) { return nil, nil } func (i *containerImageSource) GetBlob(ctx context.Context, blob types.BlobInfo) (reader io.ReadCloser, size int64, err error) { if blob.Digest == i.configDigest { logrus.Debugf("start reading config") reader := bytes.NewReader(i.config) closer := func() error { logrus.Debugf("finished reading config") return nil } return ioutils.NewReadCloserWrapper(reader, closer), reader.Size(), nil } layerFile, err := os.OpenFile(filepath.Join(i.path, blob.Digest.String()), os.O_RDONLY, 0600) if err != nil { logrus.Debugf("error reading layer %q: %v", blob.Digest.String(), err) return nil, -1, err } size = -1 st, err := layerFile.Stat() if err != nil { logrus.Warnf("error reading size of layer %q: %v", blob.Digest.String(), err) } else { size = st.Size() } logrus.Debugf("reading layer %q", blob.Digest.String()) closer := func() error { layerFile.Close() logrus.Debugf("finished reading layer %q", blob.Digest.String()) return nil } return ioutils.NewReadCloserWrapper(layerFile, closer), size, nil } func (b *Builder) makeImageRef(manifestType, parent string, exporting bool, squash bool, compress archive.Compression, historyTimestamp *time.Time) (types.ImageReference, error) { var name reference.Named container, err := b.store.Container(b.ContainerID) if err != nil { return nil, errors.Wrapf(err, "error locating container %q", b.ContainerID) } if len(container.Names) > 0 { if parsed, err2 := reference.ParseNamed(container.Names[0]); err2 == nil { name = parsed } } if manifestType == "" { manifestType = OCIv1ImageManifest } oconfig, err := json.Marshal(&b.OCIv1) if err != nil { return nil, errors.Wrapf(err, "error encoding OCI-format image configuration") } dconfig, err := json.Marshal(&b.Docker) if err != nil { return nil, errors.Wrapf(err, "error encoding docker-format image configuration") } created := time.Now().UTC() if historyTimestamp != nil { created = historyTimestamp.UTC() } ref := &containerImageRef{ store: b.store, compression: compress, name: name, names: container.Names, containerID: container.ID, mountLabel: b.MountLabel, layerID: container.LayerID, oconfig: oconfig, dconfig: dconfig, created: created, createdBy: b.CreatedBy(), historyComment: b.HistoryComment(), annotations: b.Annotations(), preferredManifestType: manifestType, exporting: exporting, squash: squash, tarPath: b.tarPath(), parent: parent, } return ref, nil }