From 56a35d5cb9b8e10f04bc3ea7966f5beb1e8985b4 Mon Sep 17 00:00:00 2001
From: Derek McGowan <derek@mcgstyle.net>
Date: Thu, 16 Nov 2017 16:54:30 -0800
Subject: [PATCH] Update docker pusher check tag

Currently pushing a new tag to a manifest which already
exists in the registry skips the tag push because it
only checks that the manifest exists. This updates the
logic to instead check if the tag exists and is at the
same digest.

Signed-off-by: Derek McGowan <derek@mcgstyle.net>
---
 remotes/docker/pusher.go | 35 +++++++++++++++++++++++++----------
 1 file changed, 25 insertions(+), 10 deletions(-)

diff --git a/remotes/docker/pusher.go b/remotes/docker/pusher.go
index c97fd4f73..405480b54 100644
--- a/remotes/docker/pusher.go
+++ b/remotes/docker/pusher.go
@@ -52,7 +52,11 @@ func (p dockerPusher) Push(ctx context.Context, desc ocispec.Descriptor) (conten
 	case images.MediaTypeDockerSchema2Manifest, images.MediaTypeDockerSchema2ManifestList,
 		ocispec.MediaTypeImageManifest, ocispec.MediaTypeImageIndex:
 		isManifest = true
-		existCheck = path.Join("manifests", desc.Digest.String())
+		if p.tag == "" {
+			existCheck = path.Join("manifests", desc.Digest.String())
+		} else {
+			existCheck = path.Join("manifests", p.tag)
+		}
 	default:
 		existCheck = path.Join("blobs", desc.Digest.String())
 	}
@@ -71,15 +75,26 @@ func (p dockerPusher) Push(ctx context.Context, desc ocispec.Descriptor) (conten
 		log.G(ctx).WithError(err).Debugf("Unable to check existence, continuing with push")
 	} else {
 		if resp.StatusCode == http.StatusOK {
-			p.tracker.SetStatus(ref, Status{
-				Status: content.Status{
-					Ref: ref,
-					// TODO: Set updated time?
-				},
-			})
-			return nil, errors.Wrapf(errdefs.ErrAlreadyExists, "content %v on remote", desc.Digest)
-		}
-		if resp.StatusCode != http.StatusNotFound {
+			var exists bool
+			if isManifest && p.tag != "" {
+				dgstHeader := digest.Digest(resp.Header.Get("Docker-Content-Digest"))
+				if dgstHeader == desc.Digest {
+					exists = true
+				}
+			} else {
+				exists = true
+			}
+
+			if exists {
+				p.tracker.SetStatus(ref, Status{
+					Status: content.Status{
+						Ref: ref,
+						// TODO: Set updated time?
+					},
+				})
+				return nil, errors.Wrapf(errdefs.ErrAlreadyExists, "content %v on remote", desc.Digest)
+			}
+		} else if resp.StatusCode != http.StatusNotFound {
 			// TODO: log error
 			return nil, errors.Errorf("unexpected response: %s", resp.Status)
 		}