remotecache: enable image-manifest by default

Signed-off-by: Tonis Tiigi <tonistiigi@gmail.com>

README.md

@@ -462,7 +462,7 @@ buildctl build ... \
   * `min`: only export layers for the resulting image
   * `max`: export all the layers of all intermediate steps
 * `ref=<ref>`: specify repository reference to store cache, e.g. `docker.io/user/image:tag`
-* `image-manifest=<true|false>`: whether to export cache manifest as an OCI-compatible image manifest rather than a manifest list/index (default: `false`, must be used with `oci-mediatypes=true`)
+* `image-manifest=<true|false>`: whether to export cache manifest as an OCI-compatible image manifest rather than a manifest list/index (default: `true` since BuildKit `v0.21`, must be used with `oci-mediatypes=true`)
 * `oci-mediatypes=<true|false>`: whether to use OCI mediatypes in exported manifests (default: `true`, since BuildKit `v0.8`)
 * `compression=<uncompressed|gzip|estargz|zstd>`: choose compression type for layers newly created and cached, gzip is default value. estargz and zstd should be used with `oci-mediatypes=true`
 * `compression-level=<value>`: choose compression level for gzip, estargz (0-9) and zstd (0-22)
@@ -489,7 +489,7 @@ The directory layout conforms to OCI Image Spec v1.0.
   * `max`: export all the layers of all intermediate steps
 * `dest=<path>`: destination directory for cache exporter
 * `tag=<tag>`: specify custom tag of image to write to local index (default: `latest`)
-* `image-manifest=<true|false>`: whether to export cache manifest as an OCI-compatible image manifest rather than a manifest list/index (default: `false`, must be used with `oci-mediatypes=true`)
+* `image-manifest=<true|false>`: whether to export cache manifest as an OCI-compatible image manifest rather than a manifest list/index (default: `true` since BuildKit `v0.21`, must be used with `oci-mediatypes=true`)
 * `oci-mediatypes=<true|false>`: whether to use OCI mediatypes in exported manifests (default `true`, since BuildKit `v0.8`)
 * `compression=<uncompressed|gzip|estargz|zstd>`: choose compression type for layers newly created and cached, gzip is default value. estargz and zstd should be used with `oci-mediatypes=true`.
 * `compression-level=<value>`: compression level for gzip, estargz (0-9) and zstd (0-22)

cache/remotecache/local/local.go

@@ -51,7 +51,7 @@ func ResolveCacheExporterFunc(sm *session.Manager) remotecache.ResolveCacheExpor
 			}
 			ociMediatypes = b
 		}
-		imageManifest := false
+		imageManifest := true
 		if v, ok := attrs[attrImageManifest]; ok {
 			b, err := strconv.ParseBool(v)
 			if err != nil {

cache/remotecache/registry/registry.go

@@ -69,7 +69,7 @@ func ResolveCacheExporterFunc(sm *session.Manager, hosts docker.RegistryHosts) r
 			}
 			ociMediatypes = b
 		}
-		imageManifest := false
+		imageManifest := true
 		if v, ok := attrs[attrImageManifest]; ok {
 			b, err := strconv.ParseBool(v)
 			if err != nil {

client/client_test.go

@@ -5661,8 +5661,9 @@ func testZstdLocalCacheExport(t *testing.T, sb integration.Sandbox) {
 			{
 				Type: "local",
 				Attrs: map[string]string{
-					"dest":        destDir,
-					"compression": "zstd",
+					"dest":           destDir,
+					"image-manifest": "false",
+					"compression":    "zstd",
 				},
 			},
 		},
@@ -5913,7 +5914,6 @@ func testImageManifestRegistryCacheImportExport(t *testing.T, sb integration.San
 		Type: "registry",
 		Attrs: map[string]string{
 			"ref":            target,
-			"image-manifest": "true",
 			"oci-mediatypes": "true",
 			"mode":           "max",
 		},
@@ -5947,6 +5947,7 @@ func testZstdRegistryCacheImportExport(t *testing.T, sb integration.Sandbox) {
 			"ref":               target,
 			"compression":       "zstd",
 			"force-compression": "true",
+			"image-manifest":    "false",
 			"oci-mediatypes":    "true", // containerd applier supports only zstd with oci-mediatype.
 		},
 	}

frontend/dockerfile/dockerfile_test.go

@@ -5802,7 +5802,6 @@ COPY --from=base unique /
 				Attrs: map[string]string{
 					"ref":            target,
 					"oci-mediatypes": "true",
-					"image-manifest": "true",
 				},
 			},
 		},
@@ -8985,7 +8984,6 @@ COPY --link foo foo
 						Attrs: map[string]string{
 							"ref":            target + "-cache",
 							"oci-mediatypes": "true",
-							"image-manifest": "true",
 						},
 					},
 				},