Fix #858 Add --all sync flag to emulate copy --all

This replicates the --all copy flag to sync to perform the same
behavior. Namely, the default is CopySystemImage unless --all is passed
which changes the behavior to CopyAllImages. While it is probably
desirable for --all to be the default as there is no option to override
ones architecture with the sync command, --all can potentially break
existing sync incantations depending on registry support. Hence
CopySystemImage remains the default.

Signed-off-by: Andrew DeMaria <ademaria@cloudflare.com>

cmd/skopeo/sync.go

@@ -36,6 +36,7 @@ type syncOptions struct {
 	source            string // Source repository name
 	destination       string // Destination registry name
 	scoped            bool   // When true, namespace copied images at destination using the source repository name
+	all               bool   // Copy all of the images if an image in the source is a list
 }
 
 // repoDescriptor contains information of a single repository used as a sync source.
@@ -97,6 +98,7 @@ See skopeo-sync(1) for details.
 	flags.StringVarP(&opts.source, "src", "s", "", "SOURCE transport type")
 	flags.StringVarP(&opts.destination, "dest", "d", "", "DESTINATION transport type")
 	flags.BoolVar(&opts.scoped, "scoped", false, "Images at DESTINATION are prefix using the full source image path as scope")
+	flags.BoolVarP(&opts.all, "all", "a", false, "Copy all images if SOURCE-IMAGE is a list")
 	flags.AddFlagSet(&sharedFlags)
 	flags.AddFlagSet(&srcFlags)
 	flags.AddFlagSet(&destFlags)
@@ -523,6 +525,11 @@ func (opts *syncOptions) run(args []string, stdout io.Writer) error {
 		return errors.New("sync from 'dir' to 'dir' not implemented, consider using rsync instead")
 	}
 
+	imageListSelection := copy.CopySystemImage
+	if opts.all {
+		imageListSelection = copy.CopyAllImages
+	}
+
 	sourceCtx, err := opts.srcImage.newSystemContext()
 	if err != nil {
 		return err
@@ -548,10 +555,11 @@ func (opts *syncOptions) run(args []string, stdout io.Writer) error {
 
 	imagesNumber := 0
 	options := copy.Options{
-		RemoveSignatures: opts.removeSignatures,
-		SignBy:           opts.signByFingerprint,
-		ReportWriter:     os.Stdout,
-		DestinationCtx:   destinationCtx,
+		RemoveSignatures:   opts.removeSignatures,
+		SignBy:             opts.signByFingerprint,
+		ReportWriter:       os.Stdout,
+		DestinationCtx:     destinationCtx,
+		ImageListSelection: imageListSelection,
 	}
 
 	for _, srcRepo := range srcRepoList {

docs/skopeo-sync.1.md

@@ -32,6 +32,11 @@ When the `--scoped` option is specified, images are prefixed with the source ima
 name can be stored at _destination_.
 
 ## OPTIONS
+**--all**
+If one of the images in __src__ refers to a list of images, instead of copying just the image which matches the current OS and
+architecture (subject to the use of the global --override-os, --override-arch and --override-variant options), attempt to copy all of
+the images in the list, and the list itself.
+
 **--authfile** _path_
 
 Path of the authentication file. Default is ${XDG\_RUNTIME\_DIR}/containers/auth.json, which is set using `skopeo login`.

integration/sync_test.go

@@ -117,6 +117,34 @@ func (s *SyncSuite) TestDocker2DirTagged(c *check.C) {
 	c.Assert(out, check.Equals, "")
 }
 
+func (s *SyncSuite) TestDocker2DirTaggedAll(c *check.C) {
+	tmpDir, err := ioutil.TempDir("", "skopeo-sync-test")
+	c.Assert(err, check.IsNil)
+	defer os.RemoveAll(tmpDir)
+
+	// FIXME: It would be nice to use one of the local Docker registries instead of neeeding an Internet connection.
+	image := "busybox:latest"
+	imageRef, err := docker.ParseReference(fmt.Sprintf("//%s", image))
+	c.Assert(err, check.IsNil)
+	imagePath := imageRef.DockerReference().String()
+
+	dir1 := path.Join(tmpDir, "dir1")
+	dir2 := path.Join(tmpDir, "dir2")
+
+	// sync docker => dir
+	assertSkopeoSucceeds(c, "", "sync", "--all", "--scoped", "--src", "docker", "--dest", "dir", image, dir1)
+	_, err = os.Stat(path.Join(dir1, imagePath, "manifest.json"))
+	c.Assert(err, check.IsNil)
+
+	// copy docker => dir
+	assertSkopeoSucceeds(c, "", "copy", "--all", "docker://"+image, "dir:"+dir2)
+	_, err = os.Stat(path.Join(dir2, "manifest.json"))
+	c.Assert(err, check.IsNil)
+
+	out := combinedOutputOfCommand(c, "diff", "-urN", path.Join(dir1, imagePath), dir2)
+	c.Assert(out, check.Equals, "")
+}
+
 func (s *SyncSuite) TestScoped(c *check.C) {
 	// FIXME: It would be nice to use one of the local Docker registries instead of needing an Internet connection.
 	image := "busybox:latest"