Update copy command cache key logic

Include the digest of the stage specified in the --from argument for
COPY commands which use --from

pkg/commands/copy.go

@@ -161,6 +161,10 @@ func (c *CopyCommand) CacheCommand(img v1.Image) DockerCommand {
  }
 }
 
+func (c *CopyCommand) From() string {
+ return cr.cmd.From
+}
+
 type CachingCopyCommand struct {
  BaseCommand
  img v1.Image

pkg/config/stage.go

@@ -16,7 +16,9 @@ limitations under the License.
 
 package config
 
-import "github.com/moby/buildkit/frontend/dockerfile/instructions"
+import (
+ "github.com/moby/buildkit/frontend/dockerfile/instructions"
+)
 
 // KanikoStage wraps a stage of the Dockerfile and provides extra information
 type KanikoStage struct {

pkg/executor/build.go

@@ -63,10 +63,11 @@ type stageBuilder struct {
  cmds []commands.DockerCommand
  args *dockerfile.BuildArgs
  crossStageDeps map[int][]string
+ digestMap map[string]v1.Hash
 }
 
 // newStageBuilder returns a new type stageBuilder which contains all the information required to build the stage
-func newStageBuilder(opts *config.KanikoOptions, stage config.KanikoStage, crossStageDeps map[int][]string) (*stageBuilder, error) {
+func newStageBuilder(opts *config.KanikoOptions, stage config.KanikoStage, crossStageDeps map[int][]string, dm map[string]v1.Hash) (*stageBuilder, error) {
  sourceImage, err := util.RetrieveSourceImage(stage, opts)
  if err != nil {
  return nil, err
@@ -100,6 +101,7 @@ func newStageBuilder(opts *config.KanikoOptions, stage config.KanikoStage, cross
  baseImageDigest: digest.String(),
  opts: opts,
  crossStageDeps: crossStageDeps,
+ digestMap: dm,
  }
 
  for _, cmd := range s.stage.Commands {
@@ -147,6 +149,15 @@ func (s *stageBuilder) optimize(compositeKey CompositeCache, cfg v1.Config) erro
  if command == nil {
  continue
  }
+ switch v := command.(type) {
+ case *commands.CopyCommand:
+ if v.From() != "" {
+ digest := s.digestMap[v.From()].String()
+ logrus.Debugf("adding digest %v from previous stage to composite key for %v", digest, command.String())
+ compositeKey.AddKey(digest)
+ }
+ }
+
  compositeKey.AddKey(command.String())
  // If the command uses files from the context, add them.
  files, err := command.FilesUsedFromContext(&cfg, s.args)
@@ -283,6 +294,7 @@ func (s *stageBuilder) build() error {
  if err := cacheGroup.Wait(); err != nil {
  logrus.Warnf("error uploading layer to cache: %s", err)
  }
+
  return nil
 }
 
@@ -354,7 +366,6 @@ func (s *stageBuilder) saveSnapshotToImage(createdBy string, tarPath string) err
  },
  )
  return err
-
 }
 
 func CalculateDependencies(opts *config.KanikoOptions) (map[int][]string, error) {
@@ -422,6 +433,9 @@ func CalculateDependencies(opts *config.KanikoOptions) (map[int][]string, error)
 // DoBuild executes building the Dockerfile
 func DoBuild(opts *config.KanikoOptions) (v1.Image, error) {
  t := timing.Start("Total Build Time")
+
+ digestMap := make(map[string]v1.Hash)
+
  // Parse dockerfile and unpack base image to root
  stages, err := dockerfile.Stages(opts)
  if err != nil {
@@ -442,13 +456,21 @@ func DoBuild(opts *config.KanikoOptions) (v1.Image, error) {
  logrus.Infof("Built cross stage deps: %v", crossStageDependencies)
 
  for index, stage := range stages {
- sb, err := newStageBuilder(opts, stage, crossStageDependencies)
+ sb, err := newStageBuilder(opts, stage, crossStageDependencies, digestMap)
  if err != nil {
  return nil, err
  }
  if err := sb.build(); err != nil {
  return nil, errors.Wrap(err, "error building stage")
  }
+
+ d, err := sb.image.Digest()
+ if err != nil {
+ return nil, err
+ }
+
+ digestMap[fmt.Sprintf("%d", sb.stage.Index)] = d
+
  reviewConfig(stage, &sb.cf.Config)
  sourceImage, err := mutate.Config(sb.image, sb.cf.Config)
  if err != nil {