libimage: pull: normalize docker-daemon

Normalize images pulled from the docker-daemon transport to docker.io
and not to localhost.  That preserves previous behavior of Podman.

Also fix a parsing bug in the pull code that was revealed while testing
the changes; parsing errors should be returned if there is a matching
transport without falling through to pulling the input string as an
image from a registry.

Context: containers/podman/issues/10998
Signed-off-by: Valentin Rothberg <rothberg@redhat.com>

libimage/pull.go

@@ -10,6 +10,7 @@ import (
 	"github.com/containers/common/pkg/config"
 	registryTransport "github.com/containers/image/v5/docker"
 	dockerArchiveTransport "github.com/containers/image/v5/docker/archive"
+	dockerDaemonTransport "github.com/containers/image/v5/docker/daemon"
 	"github.com/containers/image/v5/docker/reference"
 	ociArchiveTransport "github.com/containers/image/v5/oci/archive"
 	ociTransport "github.com/containers/image/v5/oci/layout"
@@ -55,6 +56,13 @@ func (r *Runtime) Pull(ctx context.Context, name string, pullPolicy config.PullP
 	var possiblyUnqualifiedName string // used for short-name resolution
 	ref, err := alltransports.ParseImageName(name)
 	if err != nil {
+		// Check whether `name` points to a transport.  If so, we
+		// return the error.  Otherwise we assume that `name` refers to
+		// an image on a registry (e.g., "fedora").
+		if alltransports.TransportFromImageName(name) != nil {
+			return nil, err
+		}
+
 		// If the image clearly refers to a local one, we can look it up directly.
 		// In fact, we need to since they are not parseable.
 		if strings.HasPrefix(name, "sha256:") || (len(name) == 64 && !strings.ContainsAny(name, "/.:@")) {
@@ -169,6 +177,15 @@ func (r *Runtime) copyFromDefault(ctx context.Context, ref types.ImageReference,
 	var storageName, imageName string
 	switch ref.Transport().Name() {
 
+	case dockerDaemonTransport.Transport.Name():
+		// Normalize to docker.io if needed (see containers/podman/issues/10998).
+		named, err := reference.ParseNormalizedNamed(ref.StringWithinTransport())
+		if err != nil {
+			return nil, err
+		}
+		imageName = named.String()
+		storageName = imageName
+
 	case ociTransport.Transport.Name():
 		split := strings.SplitN(ref.StringWithinTransport(), ":", 2)
 		storageName = toLocalImageName(split[0])

libimage/pull_test.go

@@ -19,6 +19,12 @@ func TestPull(t *testing.T) {
 	pullOptions := &PullOptions{}
 	pullOptions.Writer = os.Stdout
 
+	// Make sure that parsing errors of the daemon transport are returned
+	// and that we do not fallthrough attempting to pull the specified
+	// string as an image from a registry.
+	_, err := runtime.Pull(ctx, "docker-daemon:alpine", config.PullPolicyAlways, pullOptions)
+	require.Error(t, err, "return parsing error from daemon transport")
+
 	for _, test := range []struct {
 		input       string
 		expectError bool