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image.go
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image.go
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package buildah
import (
"archive/tar"
"bytes"
"context"
"encoding/json"
"errors"
"fmt"
"io"
"os"
"path/filepath"
"strings"
"time"
"github.com/containers/buildah/copier"
"github.com/containers/buildah/define"
"github.com/containers/buildah/docker"
"github.com/containers/buildah/internal/config"
"github.com/containers/buildah/internal/mkcw"
"github.com/containers/buildah/internal/tmpdir"
"github.com/containers/image/v5/docker/reference"
"github.com/containers/image/v5/image"
"github.com/containers/image/v5/manifest"
is "github.com/containers/image/v5/storage"
"github.com/containers/image/v5/types"
"github.com/containers/storage"
"github.com/containers/storage/pkg/archive"
"github.com/containers/storage/pkg/idtools"
"github.com/containers/storage/pkg/ioutils"
digest "github.com/opencontainers/go-digest"
specs "github.com/opencontainers/image-spec/specs-go"
v1 "github.com/opencontainers/image-spec/specs-go/v1"
"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 = define.OCIv1ImageManifest
// 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 = define.Dockerv2ImageManifest
)
// ExtractRootfsOptions is consumed by ExtractRootfs() which allows users to
// control whether various information like the like setuid and setgid bits and
// xattrs are preserved when extracting file system objects.
type ExtractRootfsOptions struct {
StripSetuidBit bool // strip the setuid bit off of items being extracted.
StripSetgidBit bool // strip the setgid bit off of items being extracted.
StripXattrs bool // don't record extended attributes of items being extracted.
}
type containerImageRef struct {
fromImageName string
fromImageID string
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
squash bool
confidentialWorkload ConfidentialWorkloadOptions
omitHistory bool
emptyLayer bool
idMappingOptions *define.IDMappingOptions
parent string
blobDirectory string
preEmptyLayers []v1.History
postEmptyLayers []v1.History
overrideChanges []string
overrideConfig *manifest.Schema2Config
extraImageContent map[string]string
}
type blobLayerInfo struct {
ID string
Size int64
}
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
blobDirectory string
blobLayers map[digest.Digest]blobLayerInfo
}
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 computeLayerMIMEType(what string, layerCompression archive.Compression) (omediaType, dmediaType string, err error) {
omediaType = v1.MediaTypeImageLayer
dmediaType = docker.V2S2MediaTypeUncompressedLayer
if layerCompression != archive.Uncompressed {
switch layerCompression {
case archive.Gzip:
omediaType = v1.MediaTypeImageLayerGzip
dmediaType = manifest.DockerV2Schema2LayerMediaType
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")
case archive.Zstd:
// Until the image specs define a media type for zstd-compressed layers, even if we know
// how to decompress them, we can't try to compress layers with zstd.
return "", "", errors.New("media type for zstd-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 a filesystem image, wrapped
// in LUKS-compatible encryption.
func (i *containerImageRef) extractConfidentialWorkloadFS(options ConfidentialWorkloadOptions) (io.ReadCloser, error) {
var image v1.Image
if err := json.Unmarshal(i.oconfig, &image); err != nil {
return nil, fmt.Errorf("recreating OCI configuration for %q: %w", i.containerID, err)
}
if options.TempDir == "" {
cdir, err := i.store.ContainerDirectory(i.containerID)
if err != nil {
return nil, fmt.Errorf("getting the per-container data directory for %q: %w", i.containerID, err)
}
tempdir, err := os.MkdirTemp(cdir, "buildah-rootfs")
if err != nil {
return nil, fmt.Errorf("creating a temporary data directory to hold a rootfs image for %q: %w", i.containerID, err)
}
defer func() {
if err := os.RemoveAll(tempdir); err != nil {
logrus.Warnf("removing temporary directory %q: %v", tempdir, err)
}
}()
options.TempDir = tempdir
}
mountPoint, err := i.store.Mount(i.containerID, i.mountLabel)
if err != nil {
return nil, fmt.Errorf("mounting container %q: %w", i.containerID, err)
}
archiveOptions := mkcw.ArchiveOptions{
AttestationURL: options.AttestationURL,
CPUs: options.CPUs,
Memory: options.Memory,
TempDir: options.TempDir,
TeeType: options.TeeType,
IgnoreAttestationErrors: options.IgnoreAttestationErrors,
WorkloadID: options.WorkloadID,
DiskEncryptionPassphrase: options.DiskEncryptionPassphrase,
Slop: options.Slop,
FirmwareLibrary: options.FirmwareLibrary,
GraphOptions: i.store.GraphOptions(),
ExtraImageContent: i.extraImageContent,
}
rc, _, err := mkcw.Archive(mountPoint, &image, archiveOptions)
if err != nil {
if _, err2 := i.store.Unmount(i.containerID, false); err2 != nil {
logrus.Debugf("unmounting container %q: %v", i.containerID, err2)
}
return nil, fmt.Errorf("converting rootfs %q: %w", i.containerID, err)
}
return ioutils.NewReadCloserWrapper(rc, func() error {
if err = rc.Close(); err != nil {
err = fmt.Errorf("closing tar archive of container %q: %w", i.containerID, err)
}
if _, err2 := i.store.Unmount(i.containerID, false); err == nil {
if err2 != nil {
err2 = fmt.Errorf("unmounting container %q: %w", i.containerID, err2)
}
err = err2
} else {
logrus.Debugf("unmounting container %q: %v", i.containerID, err2)
}
return err
}), nil
}
// Extract the container's whole filesystem as if it were a single layer.
// The ExtractRootfsOptions control whether or not to preserve setuid and
// setgid bits and extended attributes on contents.
func (i *containerImageRef) extractRootfs(opts ExtractRootfsOptions) (io.ReadCloser, chan error, error) {
var uidMap, gidMap []idtools.IDMap
mountPoint, err := i.store.Mount(i.containerID, i.mountLabel)
if err != nil {
return nil, nil, fmt.Errorf("mounting container %q: %w", i.containerID, err)
}
pipeReader, pipeWriter := io.Pipe()
errChan := make(chan error, 1)
go func() {
defer close(errChan)
if len(i.extraImageContent) > 0 {
// Abuse the tar format and _prepend_ the synthesized
// data items to the archive we'll get from
// copier.Get(), in a way that looks right to a reader
// as long as we DON'T Close() the tar Writer.
filename, _, _, err := i.makeExtraImageContentDiff(false)
if err != nil {
errChan <- err
return
}
file, err := os.Open(filename)
if err != nil {
errChan <- err
return
}
defer file.Close()
if _, err = io.Copy(pipeWriter, file); err != nil {
errChan <- err
return
}
}
if i.idMappingOptions != nil {
uidMap, gidMap = convertRuntimeIDMaps(i.idMappingOptions.UIDMap, i.idMappingOptions.GIDMap)
}
copierOptions := copier.GetOptions{
UIDMap: uidMap,
GIDMap: gidMap,
StripSetuidBit: opts.StripSetuidBit,
StripSetgidBit: opts.StripSetgidBit,
StripXattrs: opts.StripXattrs,
}
err := copier.Get(mountPoint, mountPoint, copierOptions, []string{"."}, pipeWriter)
errChan <- err
pipeWriter.Close()
}()
return ioutils.NewReadCloserWrapper(pipeReader, func() error {
if err = pipeReader.Close(); err != nil {
err = fmt.Errorf("closing tar archive of container %q: %w", i.containerID, err)
}
if _, err2 := i.store.Unmount(i.containerID, false); err == nil {
if err2 != nil {
err2 = fmt.Errorf("unmounting container %q: %w", i.containerID, err2)
}
err = err2
}
return err
}), errChan, 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 := time.Now().UTC()
if i.created != nil {
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.confidentialWorkload.Convert || i.squash || i.omitHistory {
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(i.parent)
dimage.Container = i.containerID
if dimage.Config != nil {
dimage.ContainerConfig = *dimage.Config
}
// 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. Clear the parent, too, to reflect
// that we no longer include its layers and history.
if i.confidentialWorkload.Convert || i.squash || i.omitHistory {
dimage.Parent = ""
dimage.History = []docker.V2S2History{}
}
// If we were supplied with a configuration, copy fields from it to
// matching fields in both formats.
if err := config.Override(dimage.Config, &oimage.Config, i.overrideChanges, i.overrideConfig); err != nil {
return v1.Image{}, v1.Manifest{}, docker.V2Image{}, docker.V2S2Manifest{}, fmt.Errorf("applying changes: %w", err)
}
// If we're producing a confidential workload, override the command and
// assorted other settings that aren't expected to work correctly.
if i.confidentialWorkload.Convert {
dimage.Config.Entrypoint = []string{"/entrypoint"}
oimage.Config.Entrypoint = []string{"/entrypoint"}
dimage.Config.Cmd = nil
oimage.Config.Cmd = nil
dimage.Config.User = ""
oimage.Config.User = ""
dimage.Config.WorkingDir = ""
oimage.Config.WorkingDir = ""
dimage.Config.Healthcheck = nil
dimage.Config.Shell = nil
dimage.Config.Volumes = nil
oimage.Config.Volumes = nil
dimage.Config.ExposedPorts = nil
oimage.Config.ExposedPorts = nil
}
// Build empty manifests. The Layers lists will be populated later.
omanifest := v1.Manifest{
Versioned: specs.Versioned{
SchemaVersion: 2,
},
MediaType: v1.MediaTypeImageManifest,
Config: v1.Descriptor{
MediaType: v1.MediaTypeImageConfig,
},
Layers: []v1.Descriptor{},
Annotations: i.annotations,
}
dmanifest := docker.V2S2Manifest{
V2Versioned: docker.V2Versioned{
SchemaVersion: 2,
MediaType: manifest.DockerV2Schema2MediaType,
},
Config: docker.V2S2Descriptor{
MediaType: manifest.DockerV2Schema2ConfigMediaType,
},
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 != manifest.DockerV2Schema2MediaType {
return nil, fmt.Errorf("no supported manifest types (attempted to use %q, only know %q and %q)",
manifestType, v1.MediaTypeImageManifest, manifest.DockerV2Schema2MediaType)
}
// 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, fmt.Errorf("unable to read layer %q: %w", layerID, err)
}
// Walk the list of parent layers, prepending each as we go. If we're squashing
// or making a confidential workload, we're only producing one layer, so 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.confidentialWorkload.Convert || i.squash {
err = nil
break
}
layer, err = i.store.Layer(layerID)
if err != nil {
return nil, fmt.Errorf("unable to read layer %q: %w", layerID, err)
}
}
layer = nil
// If we're slipping in a synthesized layer, we need to add a placeholder for it
// to the list.
const synthesizedLayerID = "(synthesized layer)"
if len(i.extraImageContent) > 0 && !i.confidentialWorkload.Convert && !i.squash {
layers = append(layers, synthesizedLayerID)
}
logrus.Debugf("layer list: %q", layers)
// Make a temporary directory to hold blobs.
path, err := os.MkdirTemp(tmpdir.GetTempDir(), define.Package)
if err != nil {
return nil, fmt.Errorf("creating temporary directory to hold layer blobs: %w", 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 layer blob directory: %v", 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.
var extraImageContentDiff string
var extraImageContentDiffDigest digest.Digest
blobLayers := make(map[digest.Digest]blobLayerInfo)
for _, layerID := range layers {
what := fmt.Sprintf("layer %q", layerID)
if i.confidentialWorkload.Convert || i.squash {
what = fmt.Sprintf("container %q", i.containerID)
}
// The default layer media type assumes no compression.
omediaType := v1.MediaTypeImageLayer
dmediaType := docker.V2S2MediaTypeUncompressedLayer
// Look up this layer.
var layerUncompressedDigest digest.Digest
var layerUncompressedSize int64
if layerID != synthesizedLayerID {
layer, err := i.store.Layer(layerID)
if err != nil {
return nil, fmt.Errorf("unable to locate layer %q: %w", layerID, err)
}
layerID = layer.ID
layerUncompressedDigest = layer.UncompressedDigest
layerUncompressedSize = layer.UncompressedSize
} else {
diffFilename, digest, size, err := i.makeExtraImageContentDiff(true)
if err != nil {
return nil, fmt.Errorf("unable to generate layer for additional content: %w", err)
}
extraImageContentDiff = diffFilename
extraImageContentDiffDigest = digest
layerUncompressedDigest = digest
layerUncompressedSize = size
}
// If we already know the digest of the contents of parent
// layers, reuse their blobsums, diff IDs, and sizes.
if !i.confidentialWorkload.Convert && !i.squash && layerID != i.layerID && layerID != synthesizedLayerID && layerUncompressedDigest != "" {
layerBlobSum := layerUncompressedDigest
layerBlobSize := layerUncompressedSize
diffID := layerUncompressedDigest
// Note this layer in the manifest, using the appropriate 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 digest.
oimage.RootFS.DiffIDs = append(oimage.RootFS.DiffIDs, diffID)
dimage.RootFS.DiffIDs = append(dimage.RootFS.DiffIDs, diffID)
blobLayers[diffID] = blobLayerInfo{
ID: layerID,
Size: layerBlobSize,
}
continue
}
// Figure out if we need to change the media type, in case we've changed the compression.
omediaType, dmediaType, err = computeLayerMIMEType(what, i.compression)
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
var errChan chan error
if i.confidentialWorkload.Convert {
// Convert the root filesystem into an encrypted disk image.
rc, err = i.extractConfidentialWorkloadFS(i.confidentialWorkload)
if err != nil {
return nil, err
}
} else if i.squash {
// Extract the root filesystem as a single layer.
rc, errChan, err = i.extractRootfs(ExtractRootfsOptions{})
if err != nil {
return nil, err
}
} else {
if layerID != synthesizedLayerID {
// If we're up to the final layer, but we don't want to
// include a diff for it, we're done.
if i.emptyLayer && layerID == i.layerID {
continue
}
// Extract this layer, one of possibly many.
rc, err = i.store.Diff("", layerID, diffOptions)
if err != nil {
return nil, fmt.Errorf("extracting %s: %w", what, err)
}
} else {
// Slip in additional content as an additional layer.
if rc, err = os.Open(extraImageContentDiff); err != nil {
return nil, err
}
}
}
srcHasher := digest.Canonical.Digester()
// 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 {
rc.Close()
return nil, fmt.Errorf("opening file for %s: %w", what, err)
}
counter := ioutils.NewWriteCounter(layerFile)
var destHasher digest.Digester
var multiWriter io.Writer
// Avoid rehashing when we do not compress.
if i.compression != archive.Uncompressed {
destHasher = digest.Canonical.Digester()
multiWriter = io.MultiWriter(counter, destHasher.Hash())
} else {
destHasher = srcHasher
multiWriter = counter
}
// Compress the layer, if we're recompressing it.
writeCloser, err := archive.CompressStream(multiWriter, i.compression)
if err != nil {
layerFile.Close()
rc.Close()
return nil, fmt.Errorf("compressing %s: %w", what, err)
}
writer := io.MultiWriter(writeCloser, srcHasher.Hash())
{
// Tweak the contents of layers we're creating.
nestedWriteCloser := ioutils.NewWriteCloserWrapper(writer, writeCloser.Close)
writeCloser = newTarFilterer(nestedWriteCloser, func(hdr *tar.Header) (bool, bool, io.Reader) {
// Scrub any local user names that might correspond to UIDs or GIDs of
// files in this layer.
hdr.Uname, hdr.Gname = "", ""
// Use specified timestamps in the layer, if we're doing that for history
// entries.
if i.created != nil {
// Changing a zeroed field to a non-zero field can affect the
// format that the library uses for writing the header, so only
// change fields that are already set to avoid changing the
// format (and as a result, changing the length) of the header
// that we write.
if !hdr.ModTime.IsZero() {
hdr.ModTime = *i.created
}
if !hdr.AccessTime.IsZero() {
hdr.AccessTime = *i.created
}
if !hdr.ChangeTime.IsZero() {
hdr.ChangeTime = *i.created
}
return false, false, nil
}
return false, false, nil
})
writer = io.Writer(writeCloser)
}
// Okay, copy from the raw diff through the filter, compressor, and counter and
// digesters.
size, err := io.Copy(writer, rc)
if err := writeCloser.Close(); err != nil {
layerFile.Close()
rc.Close()
return nil, fmt.Errorf("storing %s to file: %w on pipe close", what, err)
}
if err := layerFile.Close(); err != nil {
rc.Close()
return nil, fmt.Errorf("storing %s to file: %w on file close", what, err)
}
rc.Close()
if errChan != nil {
err = <-errChan
if err != nil {
return nil, fmt.Errorf("extracting container rootfs: %w", err)
}
}
if err != nil {
return nil, fmt.Errorf("storing %s to file: %w", what, err)
}
if i.compression == archive.Uncompressed {
if size != counter.Count {
return nil, fmt.Errorf("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, uncompressed digest %s, possibly-compressed digest %s", what, size, srcHasher.Digest().String(), destHasher.Digest().String())
// Rename the layer so that we can more easily find it by digest later.
finalBlobName := filepath.Join(path, destHasher.Digest().String())
if err = os.Rename(filepath.Join(path, "layer"), finalBlobName); err != nil {
return nil, fmt.Errorf("storing %s to file while renaming %q to %q: %w", what, filepath.Join(path, "layer"), finalBlobName, err)
}
// 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.
appendHistory := func(history []v1.History) {
for i := range history {
var created *time.Time
if history[i].Created != nil {
copiedTimestamp := *history[i].Created
created = &copiedTimestamp
}
onews := v1.History{
Created: created,
CreatedBy: history[i].CreatedBy,
Author: history[i].Author,
Comment: history[i].Comment,
EmptyLayer: true,
}
oimage.History = append(oimage.History, onews)
if created == nil {
created = &time.Time{}
}
dnews := docker.V2S2History{
Created: *created,
CreatedBy: history[i].CreatedBy,
Author: history[i].Author,
Comment: history[i].Comment,
EmptyLayer: true,
}
dimage.History = append(dimage.History, dnews)
}
}
// Only attempt to append history if history was not disabled explicitly.
if !i.omitHistory {
// Keep track of how many entries the base image's history had
// before we started adding to it.
baseImageHistoryLen := len(oimage.History)
appendHistory(i.preEmptyLayers)
created := time.Now().UTC()
if i.created != nil {
created = (*i.created).UTC()
}
comment := i.historyComment
// Add a comment indicating which base image was used, if it wasn't
// just an image ID.
if strings.Contains(i.parent, i.fromImageID) && i.fromImageName != i.fromImageID {
comment += "FROM " + i.fromImageName
}
onews := v1.History{
Created: &created,
CreatedBy: i.createdBy,
Author: oimage.Author,
Comment: comment,
EmptyLayer: i.emptyLayer,
}
oimage.History = append(oimage.History, onews)
dnews := docker.V2S2History{
Created: created,
CreatedBy: i.createdBy,
Author: dimage.Author,
Comment: comment,
EmptyLayer: i.emptyLayer,
}
dimage.History = append(dimage.History, dnews)
appendHistory(i.postEmptyLayers)
// Add a history entry for the extra image content if we added a layer for it.
if extraImageContentDiff != "" {
createdBy := fmt.Sprintf(`/bin/sh -c #(nop) ADD dir:%s in /",`, extraImageContentDiffDigest.Encoded())
onews := v1.History{
Created: &created,
CreatedBy: createdBy,
}
oimage.History = append(oimage.History, onews)
dnews := docker.V2S2History{
Created: created,
CreatedBy: createdBy,
}
dimage.History = append(dimage.History, dnews)
}
// Confidence check that we didn't just create a mismatch between non-empty layers in the
// history and the number of diffIDs. Only applicable if the base image (if there was
// one) provided us at least one entry to use as a starting point.
if baseImageHistoryLen != 0 {
expectedDiffIDs := expectedOCIDiffIDs(oimage)
if len(oimage.RootFS.DiffIDs) != expectedDiffIDs {
return nil, fmt.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, fmt.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, fmt.Errorf("encoding %#v as json: %w", oimage, 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, fmt.Errorf("encoding %#v as json: %w", omanifest, err)
}
logrus.Debugf("OCIv1 manifest = %s", omanifestbytes)
// Encode the image configuration blob.
dconfig, err := json.Marshal(&dimage)
if err != nil {
return nil, fmt.Errorf("encoding %#v as json: %w", dimage, 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 = manifest.DockerV2Schema2ConfigMediaType
// Encode the manifest.
dmanifestbytes, err := json.Marshal(&dmanifest)
if err != nil {
return nil, fmt.Errorf("encoding %#v as json: %w", dmanifest, err)
}
logrus.Debugf("Docker v2s2 manifest = %s", dmanifestbytes)
// Decide which manifest and configuration blobs we'll actually output.
var config []byte
var imageManifest []byte
switch manifestType {
case v1.MediaTypeImageManifest:
imageManifest = omanifestbytes
config = oconfig
case manifest.DockerV2Schema2MediaType:
imageManifest = 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: imageManifest,
manifestType: manifestType,
blobDirectory: i.blobDirectory,
blobLayers: blobLayers,
}
return src, nil
}
func (i *containerImageRef) NewImageDestination(ctx context.Context, sc *types.SystemContext) (types.ImageDestination, error) {
return nil, errors.New("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 {
return fmt.Errorf("removing layer blob directory: %w", err)
}
return nil
}
func (i *containerImageSource) Reference() types.ImageReference {
return i.ref
}
func (i *containerImageSource) GetSignatures(ctx context.Context, instanceDigest *digest.Digest) ([][]byte, error) {
return nil, nil
}
func (i *containerImageSource) GetManifest(ctx context.Context, instanceDigest *digest.Digest) ([]byte, string, error) {
return i.manifest, i.manifestType, nil
}
func (i *containerImageSource) LayerInfosForCopy(ctx context.Context, instanceDigest *digest.Digest) ([]types.BlobInfo, error) {
return nil, nil
}
func (i *containerImageSource) HasThreadSafeGetBlob() bool {
return false
}
func (i *containerImageSource) GetBlob(ctx context.Context, blob types.BlobInfo, cache types.BlobInfoCache) (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
}
var layerReadCloser io.ReadCloser
size = -1
if blobLayerInfo, ok := i.blobLayers[blob.Digest]; ok {
noCompression := archive.Uncompressed
diffOptions := &storage.DiffOptions{
Compression: &noCompression,
}
layerReadCloser, err = i.store.Diff("", blobLayerInfo.ID, diffOptions)
size = blobLayerInfo.Size
} else {
for _, blobDir := range []string{i.blobDirectory, i.path} {
var layerFile *os.File
layerFile, err = os.OpenFile(filepath.Join(blobDir, blob.Digest.String()), os.O_RDONLY, 0600)
if err == nil {
st, err := layerFile.Stat()
if err != nil {
logrus.Warnf("error reading size of layer file %q: %v", blob.Digest.String(), err)
} else {
size = st.Size()
layerReadCloser = layerFile
break
}
layerFile.Close()
}
if !errors.Is(err, os.ErrNotExist) {
logrus.Debugf("error checking for layer %q in %q: %v", blob.Digest.String(), blobDir, err)
}
}
}
if err != nil || layerReadCloser == nil || size == -1 {
logrus.Debugf("error reading layer %q: %v", blob.Digest.String(), err)
return nil, -1, fmt.Errorf("opening layer blob: %w", err)
}
logrus.Debugf("reading layer %q", blob.Digest.String())
closer := func() error {
logrus.Debugf("finished reading layer %q", blob.Digest.String())
if err := layerReadCloser.Close(); err != nil {
return fmt.Errorf("closing layer %q after reading: %w", blob.Digest.String(), err)
}
return nil
}
return ioutils.NewReadCloserWrapper(layerReadCloser, closer), size, nil
}
// makeExtraImageContentDiff creates an archive file containing the contents of
// files named in i.extraImageContent. The footer that marks the end of the
// archive may be omitted.
func (i *containerImageRef) makeExtraImageContentDiff(includeFooter bool) (string, digest.Digest, int64, error) {
cdir, err := i.store.ContainerDirectory(i.containerID)
if err != nil {
return "", "", -1, err
}
diff, err := os.CreateTemp(cdir, "extradiff")
if err != nil {
return "", "", -1, err
}
defer diff.Close()
digester := digest.Canonical.Digester()
counter := ioutils.NewWriteCounter(digester.Hash())
tw := tar.NewWriter(io.MultiWriter(diff, counter))
created := time.Now()
if i.created != nil {
created = *i.created
}
for path, contents := range i.extraImageContent {
if err := func() error {
content, err := os.Open(contents)
if err != nil {
return err
}
defer content.Close()
st, err := content.Stat()
if err != nil {
return err
}
if err := tw.WriteHeader(&tar.Header{
Name: path,
Typeflag: tar.TypeReg,
Mode: 0o644,
ModTime: created,
Size: st.Size(),
}); err != nil {
return err
}
if _, err := io.Copy(tw, content); err != nil {
return err
}
if err := tw.Flush(); err != nil {
return err
}
return nil
}(); err != nil {
return "", "", -1, err