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commit.go
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commit.go
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package buildah
import (
"context"
"fmt"
"io"
"io/ioutil"
"strings"
"time"
"github.com/containers/buildah/pkg/blobcache"
"github.com/containers/buildah/util"
cp "github.com/containers/image/copy"
"github.com/containers/image/docker/reference"
"github.com/containers/image/manifest"
"github.com/containers/image/signature"
is "github.com/containers/image/storage"
"github.com/containers/image/transports"
"github.com/containers/image/types"
"github.com/containers/storage"
"github.com/containers/storage/pkg/archive"
"github.com/containers/storage/pkg/stringid"
digest "github.com/opencontainers/go-digest"
"github.com/pkg/errors"
"github.com/sirupsen/logrus"
)
// CommitOptions can be used to alter how an image is committed.
type CommitOptions struct {
// PreferredManifestType is the preferred type of image manifest. The
// image configuration format will be of a compatible type.
PreferredManifestType string
// Compression specifies the type of compression which is applied to
// layer blobs. The default is to not use compression, but
// archive.Gzip is recommended.
Compression archive.Compression
// SignaturePolicyPath specifies an override location for the signature
// policy which should be used for verifying the new image as it is
// being written. Except in specific circumstances, no value should be
// specified, indicating that the shared, system-wide default policy
// should be used.
SignaturePolicyPath string
// AdditionalTags is a list of additional names to add to the image, if
// the transport to which we're writing the image gives us a way to add
// them.
AdditionalTags []string
// ReportWriter is an io.Writer which will be used to log the writing
// of the new image.
ReportWriter io.Writer
// HistoryTimestamp is the timestamp used when creating new items in the
// image's history. If unset, the current time will be used.
HistoryTimestamp *time.Time
// github.com/containers/image/types SystemContext to hold credentials
// and other authentication/authorization information.
SystemContext *types.SystemContext
// IIDFile tells the builder to write the image ID to the specified file
IIDFile string
// Squash tells the builder to produce an image with a single layer
// instead of with possibly more than one layer.
Squash bool
// BlobDirectory is the name of a directory in which we'll look for
// prebuilt copies of layer blobs that we might otherwise need to
// regenerate from on-disk layers. If blobs are available, the
// manifest of the new image will reference the blobs rather than
// on-disk layers.
BlobDirectory string
// EmptyLayer tells the builder to omit the diff for the working
// container.
EmptyLayer bool
// OmitTimestamp forces epoch 0 as created timestamp to allow for
// deterministic, content-addressable builds.
OmitTimestamp bool
}
// PushOptions can be used to alter how an image is copied somewhere.
type PushOptions struct {
// Compression specifies the type of compression which is applied to
// layer blobs. The default is to not use compression, but
// archive.Gzip is recommended.
Compression archive.Compression
// SignaturePolicyPath specifies an override location for the signature
// policy which should be used for verifying the new image as it is
// being written. Except in specific circumstances, no value should be
// specified, indicating that the shared, system-wide default policy
// should be used.
SignaturePolicyPath string
// ReportWriter is an io.Writer which will be used to log the writing
// of the new image.
ReportWriter io.Writer
// Store is the local storage store which holds the source image.
Store storage.Store
// github.com/containers/image/types SystemContext to hold credentials
// and other authentication/authorization information.
SystemContext *types.SystemContext
// ManifestType is the format to use when saving the imge using the 'dir' transport
// possible options are oci, v2s1, and v2s2
ManifestType string
// BlobDirectory is the name of a directory in which we'll look for
// prebuilt copies of layer blobs that we might otherwise need to
// regenerate from on-disk layers, substituting them in the list of
// blobs to copy whenever possible.
BlobDirectory string
// Quiet is a boolean value that determines if minimal output to
// the user will be displayed, this is best used for logging.
// The default is false.
Quiet bool
}
var (
// commitPolicy bypasses any signing requirements when committing containers to images
commitPolicy = &signature.Policy{
Default: []signature.PolicyRequirement{signature.NewPRReject()},
Transports: map[string]signature.PolicyTransportScopes{
is.Transport.Name(): {
"": []signature.PolicyRequirement{
signature.NewPRInsecureAcceptAnything(),
},
},
},
}
// pushPolicy bypasses any signing requirements when pushing (copying) images from local storage
pushPolicy = commitPolicy
)
// Commit writes the contents of the container, along with its updated
// configuration, to a new image in the specified location, and if we know how,
// add any additional tags that were specified. Returns the ID of the new image
// if commit was successful and the image destination was local.
func (b *Builder) Commit(ctx context.Context, dest types.ImageReference, options CommitOptions) (string, reference.Canonical, digest.Digest, error) {
var imgID string
// If we weren't given a name, build a destination reference using a
// temporary name that we'll remove later. The correct thing to do
// would be to read the manifest and configuration blob, and ask the
// manifest for the ID that we'd give the image, but that computation
// requires that we know the digests of the layer blobs, which we don't
// want to compute here because we'll have to do it again when
// cp.Image() instantiates a source image, and we don't want to do the
// work twice.
nameToRemove := ""
if dest == nil {
nameToRemove = stringid.GenerateRandomID() + "-tmp"
dest2, err := is.Transport.ParseStoreReference(b.store, nameToRemove)
if err != nil {
return imgID, nil, "", errors.Wrapf(err, "error creating temporary destination reference for image")
}
dest = dest2
}
systemContext := getSystemContext(b.store, options.SystemContext, options.SignaturePolicyPath)
blocked, err := isReferenceBlocked(dest, systemContext)
if err != nil {
return "", nil, "", errors.Wrapf(err, "error checking if committing to registry for %q is blocked", transports.ImageName(dest))
}
if blocked {
return "", nil, "", errors.Errorf("commit access to registry for %q is blocked by configuration", transports.ImageName(dest))
}
policyContext, err := signature.NewPolicyContext(commitPolicy)
if err != nil {
return imgID, nil, "", errors.Wrapf(err, "error creating new signature policy context")
}
defer func() {
if err2 := policyContext.Destroy(); err2 != nil {
logrus.Debugf("error destroying signature policy context: %v", err2)
}
}()
// Check if the base image is already in the destination and it's some kind of local
// storage. If so, we can skip recompressing any layers that come from the base image.
exportBaseLayers := true
if transport, destIsStorage := dest.Transport().(is.StoreTransport); destIsStorage && b.FromImageID != "" {
if baseref, err := transport.ParseReference(b.FromImageID); baseref != nil && err == nil {
if img, err := transport.GetImage(baseref); img != nil && err == nil {
logrus.Debugf("base image %q is already present in local storage, no need to copy its layers", b.FromImageID)
exportBaseLayers = false
}
}
}
// Build an image reference from which we can copy the finished image.
src, err := b.makeImageRef(options, exportBaseLayers)
if err != nil {
return imgID, nil, "", errors.Wrapf(err, "error computing layer digests and building metadata for container %q", b.ContainerID)
}
// In case we're using caching, decide how to handle compression for a cache.
// If we're using blob caching, set it up for the source.
maybeCachedSrc := src
maybeCachedDest := dest
if options.BlobDirectory != "" {
compress := types.PreserveOriginal
if options.Compression != archive.Uncompressed {
compress = types.Compress
}
cache, err := blobcache.NewBlobCache(src, options.BlobDirectory, compress)
if err != nil {
return imgID, nil, "", errors.Wrapf(err, "error wrapping image reference %q in blob cache at %q", transports.ImageName(src), options.BlobDirectory)
}
maybeCachedSrc = cache
cache, err = blobcache.NewBlobCache(dest, options.BlobDirectory, compress)
if err != nil {
return imgID, nil, "", errors.Wrapf(err, "error wrapping image reference %q in blob cache at %q", transports.ImageName(dest), options.BlobDirectory)
}
maybeCachedDest = cache
}
// "Copy" our image to where it needs to be.
switch options.Compression {
case archive.Uncompressed:
systemContext.OCIAcceptUncompressedLayers = true
case archive.Gzip:
systemContext.DirForceCompress = true
}
var manifestBytes []byte
if manifestBytes, err = cp.Image(ctx, policyContext, maybeCachedDest, maybeCachedSrc, getCopyOptions(b.store, options.ReportWriter, nil, systemContext, "")); err != nil {
return imgID, nil, "", errors.Wrapf(err, "error copying layers and metadata for container %q", b.ContainerID)
}
// If we've got more names to attach, and we know how to do that for
// the transport that we're writing the new image to, add them now.
if len(options.AdditionalTags) > 0 {
switch dest.Transport().Name() {
case is.Transport.Name():
img, err := is.Transport.GetStoreImage(b.store, dest)
if err != nil {
return imgID, nil, "", errors.Wrapf(err, "error locating just-written image %q", transports.ImageName(dest))
}
if err = util.AddImageNames(b.store, "", systemContext, img, options.AdditionalTags); err != nil {
return imgID, nil, "", errors.Wrapf(err, "error setting image names to %v", append(img.Names, options.AdditionalTags...))
}
logrus.Debugf("assigned names %v to image %q", img.Names, img.ID)
default:
logrus.Warnf("don't know how to add tags to images stored in %q transport", dest.Transport().Name())
}
}
img, err := is.Transport.GetStoreImage(b.store, dest)
if err != nil && err != storage.ErrImageUnknown {
return imgID, nil, "", errors.Wrapf(err, "error locating image %q in local storage", transports.ImageName(dest))
}
if err == nil {
imgID = img.ID
prunedNames := make([]string, 0, len(img.Names))
for _, name := range img.Names {
if !(nameToRemove != "" && strings.Contains(name, nameToRemove)) {
prunedNames = append(prunedNames, name)
}
}
if len(prunedNames) < len(img.Names) {
if err = b.store.SetNames(imgID, prunedNames); err != nil {
return imgID, nil, "", errors.Wrapf(err, "failed to prune temporary name from image %q", imgID)
}
logrus.Debugf("reassigned names %v to image %q", prunedNames, img.ID)
dest2, err := is.Transport.ParseStoreReference(b.store, "@"+imgID)
if err != nil {
return imgID, nil, "", errors.Wrapf(err, "error creating unnamed destination reference for image")
}
dest = dest2
}
if options.IIDFile != "" {
if err = ioutil.WriteFile(options.IIDFile, []byte(img.ID), 0644); err != nil {
return imgID, nil, "", errors.Wrapf(err, "failed to write image ID to file %q", options.IIDFile)
}
}
}
manifestDigest, err := manifest.Digest(manifestBytes)
if err != nil {
return imgID, nil, "", errors.Wrapf(err, "error computing digest of manifest of new image %q", transports.ImageName(dest))
}
var ref reference.Canonical
if name := dest.DockerReference(); name != nil {
ref, err = reference.WithDigest(name, manifestDigest)
if err != nil {
logrus.Warnf("error generating canonical reference with name %q and digest %s: %v", name, manifestDigest.String(), err)
}
}
return imgID, ref, manifestDigest, nil
}
// Push copies the contents of the image to a new location.
func Push(ctx context.Context, image string, dest types.ImageReference, options PushOptions) (reference.Canonical, digest.Digest, error) {
systemContext := getSystemContext(options.Store, options.SystemContext, options.SignaturePolicyPath)
if options.Quiet {
options.ReportWriter = nil // Turns off logging output
}
blocked, err := isReferenceBlocked(dest, systemContext)
if err != nil {
return nil, "", errors.Wrapf(err, "error checking if pushing to registry for %q is blocked", transports.ImageName(dest))
}
if blocked {
return nil, "", errors.Errorf("push access to registry for %q is blocked by configuration", transports.ImageName(dest))
}
policyContext, err := signature.NewPolicyContext(pushPolicy)
if err != nil {
return nil, "", errors.Wrapf(err, "error creating new signature policy context")
}
// Look up the image.
src, _, err := util.FindImage(options.Store, "", systemContext, image)
if err != nil {
return nil, "", err
}
maybeCachedSrc := src
if options.BlobDirectory != "" {
compress := types.PreserveOriginal
if options.Compression != archive.Uncompressed {
compress = types.Compress
}
cache, err := blobcache.NewBlobCache(src, options.BlobDirectory, compress)
if err != nil {
return nil, "", errors.Wrapf(err, "error wrapping image reference %q in blob cache at %q", transports.ImageName(src), options.BlobDirectory)
}
maybeCachedSrc = cache
}
// Copy everything.
switch options.Compression {
case archive.Uncompressed:
systemContext.OCIAcceptUncompressedLayers = true
case archive.Gzip:
systemContext.DirForceCompress = true
}
var manifestBytes []byte
if manifestBytes, err = cp.Image(ctx, policyContext, dest, maybeCachedSrc, getCopyOptions(options.Store, options.ReportWriter, nil, systemContext, options.ManifestType)); err != nil {
return nil, "", errors.Wrapf(err, "error copying layers and metadata from %q to %q", transports.ImageName(maybeCachedSrc), transports.ImageName(dest))
}
if options.ReportWriter != nil {
fmt.Fprintf(options.ReportWriter, "")
}
manifestDigest, err := manifest.Digest(manifestBytes)
if err != nil {
return nil, "", errors.Wrapf(err, "error computing digest of manifest of new image %q", transports.ImageName(dest))
}
var ref reference.Canonical
if name := dest.DockerReference(); name != nil {
ref, err = reference.WithDigest(name, manifestDigest)
if err != nil {
logrus.Warnf("error generating canonical reference with name %q and digest %s: %v", name, manifestDigest.String(), err)
}
}
return ref, manifestDigest, nil
}