101 lines
3.2 KiB
Go
101 lines
3.2 KiB
Go
// Copyright 2018 Google LLC All Rights Reserved.
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//
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// Licensed under the Apache License, Version 2.0 (the "License");
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// you may not use this file except in compliance with the License.
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// You may obtain a copy of the License at
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//
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// http://www.apache.org/licenses/LICENSE-2.0
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//
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// Unless required by applicable law or agreed to in writing, software
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// distributed under the License is distributed on an "AS IS" BASIS,
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// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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// See the License for the specific language governing permissions and
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// limitations under the License.
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package mutate
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import (
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"fmt"
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"github.com/google/go-containerregistry/v1"
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"github.com/google/go-containerregistry/v1/empty"
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)
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type RebaseOptions struct {
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// TODO(jasonhall): Rebase seam hint.
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}
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func Rebase(orig, oldBase, newBase v1.Image, opts *RebaseOptions) (v1.Image, error) {
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// Verify that oldBase's layers are present in orig, otherwise orig is
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// not based on oldBase at all.
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origLayers, err := orig.Layers()
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if err != nil {
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return nil, fmt.Errorf("failed to get layers for original: %v", err)
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}
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oldBaseLayers, err := oldBase.Layers()
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if err != nil {
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return nil, err
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}
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if len(oldBaseLayers) > len(origLayers) {
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return nil, fmt.Errorf("image %q is not based on %q (too few layers)", orig, oldBase)
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}
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for i, l := range oldBaseLayers {
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oldLayerDigest, err := l.Digest()
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if err != nil {
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return nil, fmt.Errorf("failed to get digest of layer %d of %q: %v", i, oldBase, err)
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}
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origLayerDigest, err := origLayers[i].Digest()
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if err != nil {
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return nil, fmt.Errorf("failed to get digest of layer %d of %q: %v", i, orig, err)
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}
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if oldLayerDigest != origLayerDigest {
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return nil, fmt.Errorf("image %q is not based on %q (layer %d mismatch)", orig, oldBase, i)
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}
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}
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origConfig, err := orig.ConfigFile()
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if err != nil {
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return nil, fmt.Errorf("failed to get config for original: %v", err)
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}
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// Stitch together an image that contains:
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// - original image's config
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// - new base image's layers + top of original image's layers
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// - new base image's history + top of original image's history
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rebasedImage, err := Config(empty.Image, *origConfig.Config.DeepCopy())
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if err != nil {
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return nil, fmt.Errorf("failed to create empty image with original config: %v", err)
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}
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// Get new base layers and config for history.
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newBaseLayers, err := newBase.Layers()
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if err != nil {
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return nil, fmt.Errorf("could not get new base layers for new base: %v", err)
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}
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newConfig, err := newBase.ConfigFile()
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if err != nil {
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return nil, fmt.Errorf("could not get config for new base: %v", err)
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}
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// Add new base layers.
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for i := range newBaseLayers {
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rebasedImage, err = Append(rebasedImage, Addendum{
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Layer: newBaseLayers[i],
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History: newConfig.History[i],
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})
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if err != nil {
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return nil, fmt.Errorf("failed to append layer %d of new base layers", i)
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}
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}
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// Add original layers above the old base.
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start := len(oldBaseLayers)
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for i := range origLayers[start:] {
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rebasedImage, err = Append(rebasedImage, Addendum{
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Layer: origLayers[start+i],
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History: origConfig.History[start+i],
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})
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if err != nil {
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return nil, fmt.Errorf("failed to append layer %d of original layers", i)
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}
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}
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return rebasedImage, nil
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}
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