Merge pull request #4012 from deitch/remote-tag-with-copy

remote-tag enable copying across repositories and registries

src/cmd/linuxkit/pkg_remotetag.go

@@ -4,6 +4,7 @@ import (
 	"fmt"
 
 	"github.com/google/go-containerregistry/pkg/authn"
+	"github.com/google/go-containerregistry/pkg/crane"
 	namepkg "github.com/google/go-containerregistry/pkg/name"
 	"github.com/google/go-containerregistry/pkg/v1/remote"
 	"github.com/linuxkit/linuxkit/src/cmd/linuxkit/util"
@@ -19,9 +20,13 @@ func pkgRemoteTagCmd() *cobra.Command {
 		Long: `Tag a package in a remote registry with another tag, without downloading or pulling.
 		Will simply tag using the identical descriptor.
 		First argument is "from" tag, second is "to" tag.
+
+		If the "to" and "from" repositories are the same, then it is a simple tag operation.
+		If they are not, then the "from" image is pulled and pushed to the "to" repository.
 `,
 		Args: cobra.ExactArgs(2),
 		RunE: func(cmd *cobra.Command, args []string) error {
+			var finalErr error
 			from := args[0]
 			to := args[1]
 			remoteOptions := []remote.Option{remote.WithAuthFromKeychain(authn.DefaultKeychain)}
@@ -48,15 +53,19 @@ func pkgRemoteTagCmd() *cobra.Command {
 				}
 				log.Infof("image %s already exists in the registry, but is different from %s, overwriting", toFullname, fromFullname)
 			}
-			toTag, err := namepkg.NewTag(toFullname)
-			if err != nil {
-				return err
-			}
-			if err := remote.Tag(toTag, fromDesc, remoteOptions...); err != nil {
-				return fmt.Errorf("error tagging image %s as %s: %v", fromFullname, toFullname, err)
+			// see if they are from the same sources
+			if fromRef.Context().String() == toRef.Context().String() {
+				toTag, err := namepkg.NewTag(toFullname)
+				if err != nil {
+					return err
+				}
+				finalErr = remote.Tag(toTag, fromDesc, remoteOptions...)
+			} else {
+				// different, so need to copy
+				finalErr = crane.Copy(fromFullname, toFullname)
 			}
 
-			return nil
+			return finalErr
 		},
 	}
 	cmd.Flags().StringVar(&release, "release", "", "Release the given version")