Fix content not found with push=true,rewrite-timestamp=true

Fix issue 4793

Signed-off-by: Akihiro Suda <akihiro.suda.cz@hco.ntt.co.jp>
(cherry picked from commit 8bd3dd8)
Signed-off-by: Akihiro Suda <akihiro.suda.cz@hco.ntt.co.jp>

exporter/containerimage/export.go

@@ -339,18 +339,7 @@ func (e *imageExporterInstance) Export(ctx context.Context, src *exporter.Source
 				}
 			}
 			if e.push {
-				if opts.RewriteTimestamp {
-					annotations := map[digest.Digest]map[string]string{}
-					addAnnotations(annotations, *desc)
-					// e.pushImage cannot be used because src ref does not point to the rewritten image
-					//
-					// TODO: change e.pushImage so that it takes Result[Remote] as parameter.
-					// https://github.com/moby/buildkit/pull/4057#discussion_r1324106088
-					err = push.Push(ctx, e.opt.SessionManager, sessionID, e.opt.ImageWriter.opt.ContentStore, e.opt.ImageWriter.ContentStore(),
-						desc.Digest, targetName, e.insecure, e.opt.RegistryHosts, e.pushByDigest, annotations)
-				} else {
-					err = e.pushImage(ctx, src, sessionID, targetName, desc.Digest)
-				}
+				err = e.pushImage(ctx, src, sessionID, targetName, desc.Digest)
 				if err != nil {
 					return nil, nil, errors.Wrapf(err, "failed to push %v", targetName)
 				}

frontend/dockerfile/dockerfile_test.go

@@ -6882,6 +6882,7 @@ func testReproSourceDateEpoch(t *testing.T, sb integration.Sandbox) {
 		dockerfile     string
 		files          []fstest.Applier
 		expectedDigest string
+		noCacheExport  bool
 	}
 	testCases := []testCase{
 		{
@@ -6909,6 +6910,14 @@ COPY --link foo foo
 			files:          []fstest.Applier{fstest.CreateFile("foo", []byte("foo"), 0600)},
 			expectedDigest: "sha256:9f75e4bdbf3d825acb36bb603ddef4a25742afb8ccb674763ffc611ae047d8a6",
 		},
+		{
+			// https://github.com/moby/buildkit/issues/4793
+			name: "NoAdditionalLayer",
+			dockerfile: `FROM amd64/debian:bullseye-20230109-slim
+`,
+			expectedDigest: "sha256:eeba8ef81dec46359d099c5d674009da54e088fa8f29945d4d7fb3a7a88c450e",
+			noCacheExport:  true, // "skipping cache export for empty result"
+		},
 	}
 
 	// https://explore.ggcr.dev/?image=amd64%2Fdebian%3Abullseye-20230109-slim
@@ -6968,7 +6977,10 @@ COPY --link foo foo
 			require.NoError(t, err)
 
 			desc, manifest, img := readImage(t, ctx, target)
-			_, cacheManifest, _ := readImage(t, ctx, target+"-cache")
+			var cacheManifest ocispecs.Manifest
+			if !tc.noCacheExport {
+				_, cacheManifest, _ = readImage(t, ctx, target+"-cache")
+			}
 			t.Log("The digest may change depending on the BuildKit version, the snapshotter configuration, etc.")
 			require.Equal(t, tc.expectedDigest, desc.Digest.String())
 
@@ -6986,9 +6998,11 @@ COPY --link foo foo
 					require.Equal(t, fmt.Sprintf("%d", tm.Unix()), l.Annotations["buildkit/rewritten-timestamp"])
 				}
 			}
-			// Cache layers must *not* have rewritten-timestamp
-			for _, l := range cacheManifest.Layers {
-				require.Empty(t, l.Annotations["buildkit/rewritten-timestamp"])
+			if !tc.noCacheExport {
+				// Cache layers must *not* have rewritten-timestamp
+				for _, l := range cacheManifest.Layers {
+					require.Empty(t, l.Annotations["buildkit/rewritten-timestamp"])
+				}
 			}
 
 			// Build again, after pruning the base image layer cache.