OCPBUGS-4959: oc-mirror error on second synchronisation with no change (

#605)

pkg/cli/mirror/mirror.go

@@ -858,8 +858,16 @@ func (o *MirrorOptions) diskToMirrorWrapper(ctx context.Context, cleanup cleanup
 	// Publish from disk to registry
 	// this takes care of syncing the metadata to the
 	// registry backends.
+
 	mapping, err := o.Publish(ctx)
 	if err != nil {
+		// OCPBUGS-4959 for automation processes to end gracefully
+		// when we have the same sequence - i.e nothing to do
+		msqErr := &ErrMirrorSequence{}
+		if errors.As(err, &msqErr) {
+			klog.Info("No diff from previous mirror (sequence is the same), nothing to do")
+			return cleanup()
+		}
 		serr := &ErrInvalidSequence{}
 		if errors.As(err, &serr) {
 			return fmt.Errorf("error during publishing, expecting imageset with prefix mirror_seq%d: %v", serr.wantSeq, err)

pkg/cli/mirror/sequence.go

@@ -17,10 +17,18 @@ type ErrInvalidSequence struct {
 	gotSeq  int
 }
 
+type ErrMirrorSequence struct {
+	msg string
+}
+
 func (s *ErrInvalidSequence) Error() string {
 	return fmt.Sprintf("invalid mirror sequence order, want %v, got %v", s.wantSeq, s.gotSeq)
 }
 
+func (s *ErrMirrorSequence) Error() string {
+	return fmt.Sprintf(s.msg)
+}
+
 func (o *MirrorOptions) checkSequence(incoming, current v1alpha2.Metadata, backendErr error) error {
 	switch {
 	case backendErr != nil && !errors.Is(backendErr, storage.ErrMetadataNotExist):
@@ -40,6 +48,10 @@ func (o *MirrorOptions) checkSequence(incoming, current v1alpha2.Metadata, backe
 		klog.V(3).Info("Checking metadata sequence number")
 		currRun := current.PastMirror
 		incomingRun := incoming.PastMirror
+		// OCPBUGS-4959
+		if incomingRun.Sequence == currRun.Sequence {
+			return &ErrMirrorSequence{msg: "mirror sequence is the same"}
+		}
 		if incomingRun.Sequence != (currRun.Sequence + 1) {
 			return &ErrInvalidSequence{currRun.Sequence + 1, incomingRun.Sequence}
 		}