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image.go
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image.go
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// Copyright 2019 Google LLC All Rights Reserved.
//
// Licensed under the Apache License, Version 2.0 (the "License");
// you may not use this file except in compliance with the License.
// You may obtain a copy of the License at
//
// http://www.apache.org/licenses/LICENSE-2.0
//
// Unless required by applicable law or agreed to in writing, software
// distributed under the License is distributed on an "AS IS" BASIS,
// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
// See the License for the specific language governing permissions and
// limitations under the License.
package mutate
import (
"bytes"
"encoding/json"
"errors"
"strings"
v1 "github.com/google/go-containerregistry/pkg/v1"
"github.com/google/go-containerregistry/pkg/v1/partial"
"github.com/google/go-containerregistry/pkg/v1/stream"
"github.com/google/go-containerregistry/pkg/v1/types"
)
type image struct {
base v1.Image
adds []Addendum
computed bool
configFile *v1.ConfigFile
manifest *v1.Manifest
annotations map[string]string
mediaType *types.MediaType
configMediaType *types.MediaType
diffIDMap map[v1.Hash]v1.Layer
digestMap map[v1.Hash]v1.Layer
}
var _ v1.Image = (*image)(nil)
func (i *image) MediaType() (types.MediaType, error) {
if i.mediaType != nil {
return *i.mediaType, nil
}
return i.base.MediaType()
}
func (i *image) compute() error {
// Don't re-compute if already computed.
if i.computed {
return nil
}
var configFile *v1.ConfigFile
if i.configFile != nil {
configFile = i.configFile
} else {
cf, err := i.base.ConfigFile()
if err != nil {
return err
}
configFile = cf.DeepCopy()
}
diffIDs := configFile.RootFS.DiffIDs
history := configFile.History
diffIDMap := make(map[v1.Hash]v1.Layer)
digestMap := make(map[v1.Hash]v1.Layer)
for _, add := range i.adds {
history = append(history, add.History)
if add.Layer != nil {
diffID, err := add.Layer.DiffID()
if err != nil {
return err
}
diffIDs = append(diffIDs, diffID)
diffIDMap[diffID] = add.Layer
}
}
m, err := i.base.Manifest()
if err != nil {
return err
}
manifest := m.DeepCopy()
manifestLayers := manifest.Layers
for _, add := range i.adds {
if add.Layer == nil {
// Empty layers include only history in manifest.
continue
}
desc, err := partial.Descriptor(add.Layer)
if err != nil {
return err
}
// Fields in the addendum override the original descriptor.
if len(add.Annotations) != 0 {
desc.Annotations = add.Annotations
}
if len(add.URLs) != 0 {
desc.URLs = add.URLs
}
if add.MediaType != "" {
desc.MediaType = add.MediaType
}
manifestLayers = append(manifestLayers, *desc)
digestMap[desc.Digest] = add.Layer
}
configFile.RootFS.DiffIDs = diffIDs
configFile.History = history
manifest.Layers = manifestLayers
rcfg, err := json.Marshal(configFile)
if err != nil {
return err
}
d, sz, err := v1.SHA256(bytes.NewBuffer(rcfg))
if err != nil {
return err
}
manifest.Config.Digest = d
manifest.Config.Size = sz
// If Data was set in the base image, we need to update it in the mutated image.
if m.Config.Data != nil {
manifest.Config.Data = rcfg
}
// If the user wants to mutate the media type of the config
if i.configMediaType != nil {
manifest.Config.MediaType = *i.configMediaType
}
// With OCI media types, this should not be set, see discussion:
// https://github.com/opencontainers/image-spec/pull/795
if i.mediaType != nil {
if strings.Contains(string(*i.mediaType), types.OCIVendorPrefix) {
manifest.MediaType = ""
} else if strings.Contains(string(*i.mediaType), types.DockerVendorPrefix) {
manifest.MediaType = *i.mediaType
}
}
if i.annotations != nil {
if manifest.Annotations == nil {
manifest.Annotations = map[string]string{}
}
for k, v := range i.annotations {
manifest.Annotations[k] = v
}
}
i.configFile = configFile
i.manifest = manifest
i.diffIDMap = diffIDMap
i.digestMap = digestMap
i.computed = true
return nil
}
// Layers returns the ordered collection of filesystem layers that comprise this image.
// The order of the list is oldest/base layer first, and most-recent/top layer last.
func (i *image) Layers() ([]v1.Layer, error) {
if err := i.compute(); err == stream.ErrNotComputed {
// Image contains a streamable layer which has not yet been
// consumed. Just return the layers we have in case the caller
// is going to consume the layers.
layers, err := i.base.Layers()
if err != nil {
return nil, err
}
for _, add := range i.adds {
layers = append(layers, add.Layer)
}
return layers, nil
} else if err != nil {
return nil, err
}
diffIDs, err := partial.DiffIDs(i)
if err != nil {
return nil, err
}
ls := make([]v1.Layer, 0, len(diffIDs))
for _, h := range diffIDs {
l, err := i.LayerByDiffID(h)
if err != nil {
return nil, err
}
ls = append(ls, l)
}
return ls, nil
}
// ConfigName returns the hash of the image's config file.
func (i *image) ConfigName() (v1.Hash, error) {
if err := i.compute(); err != nil {
return v1.Hash{}, err
}
return partial.ConfigName(i)
}
// ConfigFile returns this image's config file.
func (i *image) ConfigFile() (*v1.ConfigFile, error) {
if err := i.compute(); err != nil {
return nil, err
}
return i.configFile.DeepCopy(), nil
}
// RawConfigFile returns the serialized bytes of ConfigFile()
func (i *image) RawConfigFile() ([]byte, error) {
if err := i.compute(); err != nil {
return nil, err
}
return json.Marshal(i.configFile)
}
// Digest returns the sha256 of this image's manifest.
func (i *image) Digest() (v1.Hash, error) {
if err := i.compute(); err != nil {
return v1.Hash{}, err
}
return partial.Digest(i)
}
// Size implements v1.Image.
func (i *image) Size() (int64, error) {
if err := i.compute(); err != nil {
return -1, err
}
return partial.Size(i)
}
// Manifest returns this image's Manifest object.
func (i *image) Manifest() (*v1.Manifest, error) {
if err := i.compute(); err != nil {
return nil, err
}
return i.manifest.DeepCopy(), nil
}
// RawManifest returns the serialized bytes of Manifest()
func (i *image) RawManifest() ([]byte, error) {
if err := i.compute(); err != nil {
return nil, err
}
return json.Marshal(i.manifest)
}
// LayerByDigest returns a Layer for interacting with a particular layer of
// the image, looking it up by "digest" (the compressed hash).
func (i *image) LayerByDigest(h v1.Hash) (v1.Layer, error) {
if cn, err := i.ConfigName(); err != nil {
return nil, err
} else if h == cn {
return partial.ConfigLayer(i)
}
if layer, ok := i.digestMap[h]; ok {
return layer, nil
}
return i.base.LayerByDigest(h)
}
// LayerByDiffID is an analog to LayerByDigest, looking up by "diff id"
// (the uncompressed hash).
func (i *image) LayerByDiffID(h v1.Hash) (v1.Layer, error) {
if layer, ok := i.diffIDMap[h]; ok {
return layer, nil
}
return i.base.LayerByDiffID(h)
}
func validate(adds []Addendum) error {
for _, add := range adds {
if add.Layer == nil && !add.History.EmptyLayer {
return errors.New("unable to add a nil layer to the image")
}
}
return nil
}