opencontainers · wking · Aug 30, 2016
diff --git a/media-types.md b/media-types.md
@@ -38,6 +38,13 @@ This section shows where the OCI Image Specification is compatible with formats
 
 - [application/vnd.docker.container.image.v1+json](https://github.com/docker/docker/blob/master/image/spec/v1.md#image-json-description)
 
+    Differences compared to the OCI schema:
+
+    * Docker's [v1.1](https://github.com/docker/docker/blob/master/image/spec/v1.1.md#container-runconfig-field-descriptions) and [v1.2](https://github.com/docker/docker/blob/master/image/spec/v1.2.md#container-runconfig-field-descriptions) declare a [`rootfs.type`] property but only document a `layers` argument.
+      The OCI configuration does not provide a `rootfs.type` property, and treats all configurations as if they used Docker's `layers` value.
+      Translators converting Docker v1.1 or v1.2 configurations to OCI configurations should error out if `rootfs.type` contains any string other than `layers`.
+      Translators converting OCI configurations to Docker v1.1 or v1.2 configurations should always set `rootfs.type` to `layers`.
+
 ## Relations
 
 The following figure shows how the above media types reference each other:

diff --git a/schema/config_test.go b/schema/config_test.go
@@ -136,8 +136,7 @@ func TestConfig(t *testing.T) {
       "diff_ids": [
         "sha256:9d3dd9504c685a304985025df4ed0283e47ac9ffa9bd0326fddf4d59513f0827",
         "sha256:2b689805fbd00b2db1df73fae47562faac1a626d5f61744bfe29946ecff5d73d"
-      ],
-      "type": "layers"
+      ]
     },
     "history": [
       {

diff --git a/schema/defs-config.json b/schema/defs-config.json
@@ -74,9 +74,6 @@
           "items": {
             "type": "string"
           }
-        },
-        "layers": {
-          "type": "string"
         }
       }
     },

diff --git a/serialization.md b/serialization.md
@@ -302,12 +302,9 @@ Note: whitespace has been added to this example for clarity. Whitespace is OPTIO
     <dd>
         The rootfs key references the layer content addresses used by the image.
 	This makes the image config hash depend on the filesystem hash.
-        rootfs has two subkeys:
+        Subkeys:
 
         <ul>
-          <li>
-            <code>type</code> is usually set to <code>layers</code>.
-          </li>
           <li>
             <code>diff_ids</code> is an array of layer content hashes (<code>DiffIDs</code>), in order from bottom-most to top-most.
           </li>
@@ -321,8 +318,7 @@ Note: whitespace has been added to this example for clarity. Whitespace is OPTIO
     "sha256:c6f988f4874bb0add23a778f753c65efe992244e148a1d2ec2a8b664fb66bbd1",
     "sha256:5f70bf18a086007016e948b04aed3b82103a36bea41755b6cddfaf10ace3c6ef",
     "sha256:13f53e08df5a220ab6d13c58b2bf83a59cbdc2e04d0a3f041ddf4b0ba4112d49"
-  ],
-  "type": "layers"
+  ]
 }</pre>
     </dd>
     <dt>

diff --git a/specs-go/v1/config.go b/specs-go/v1/config.go
@@ -49,9 +49,6 @@ type ImageConfig struct {
 
 // RootFS describes a layer content addresses
 type RootFS struct {
-	// Type is the type of the rootfs.
-	Type string `json:"type"`
-
 	// DiffIDs is an array of layer content hashes (DiffIDs), in order from bottom-most to top-most.
 	DiffIDs []string `json:"diff_ids"`
 }