Descriptor: align field order with OCI image specification

I am looking at aligning the types defined in this repository with the
OCI image specification, and potentially exchanging local types with
those from the specification.

This patch is a stepping-stone towards that effort, but as this changes
the format of the serialized JSON, I wanted to put this up first before
proceeding with the other work in case there are concerns.

Signed-off-by: Sebastiaan van Stijn <github@gone.nl>

blobs.go

@@ -63,13 +63,13 @@ type Descriptor struct {
 	// encoded as utf-8.
 	MediaType string `json:"mediaType,omitempty"`
 
-	// Size in bytes of content.
-	Size int64 `json:"size,omitempty"`
-
 	// Digest uniquely identifies the content. A byte stream can be verified
 	// against this digest.
 	Digest digest.Digest `json:"digest,omitempty"`
 
+	// Size in bytes of content.
+	Size int64 `json:"size,omitempty"`
+
 	// URLs contains the source URLs of this content.
 	URLs []string `json:"urls,omitempty"`
 

docs/notifications.md

@@ -93,8 +93,8 @@ manifest:
       "action": "pull",
       "target": {
         "mediaType": "application/vnd.docker.distribution.manifest.v2+json",
-        "size": 708,
         "digest": "sha256:fea8895f450959fa676bcc1df0611ea93823a735a01205fd8622846041d0c7cf",
+        "size": 708,
         "length": 708,
         "repository": "hello-world",
         "url": "http://192.168.100.227:5000/v2/hello-world/manifests/sha256:fea8895f450959fa676bcc1df0611ea93823a735a01205fd8622846041d0c7cf",
@@ -171,8 +171,8 @@ Content-Type: application/vnd.docker.distribution.events.v1+json
       "action": "push",
       "target": {
         "mediaType": "application/vnd.docker.distribution.manifest.v1+json",
-        "length": 1,
         "digest": "sha256:fea8895f450959fa676bcc1df0611ea93823a735a01205fd8622846041d0c7cf",
+        "length": 1,
         "repository": "library/test",
         "url": "https://example.com/v2/library/test/manifests/sha256:c3b3692957d439ac1928219a83fac91e7bf96c153725526874673ae1f2023f8d5"
       },
@@ -196,8 +196,8 @@ Content-Type: application/vnd.docker.distribution.events.v1+json
       "action": "push",
       "target": {
         "mediaType": "application/vnd.docker.container.image.rootfs.diff+x-gtar",
-        "length": 2,
         "digest": "sha256:c3b3692957d439ac1928219a83fac91e7bf96c153725526874673ae1f2023f8d5",
+        "length": 2,
         "repository": "library/test",
         "url": "https://example.com/v2/library/test/blobs/sha256:c3b3692957d439ac1928219a83fac91e7bf96c153725526874673ae1f2023f8d5"
       },
@@ -221,8 +221,8 @@ Content-Type: application/vnd.docker.distribution.events.v1+json
       "action": "push",
       "target": {
         "mediaType": "application/vnd.docker.container.image.rootfs.diff+x-gtar",
-        "length": 3,
         "digest": "sha256:c3b3692957d439ac1928219a83fac91e7bf96c153725526874673ae1f2023f8d5",
+        "length": 3,
         "repository": "library/test",
         "url": "https://example.com/v2/library/test/blobs/sha256:c3b3692957d439ac1928219a83fac91e7bf96c153725526874673ae1f2023f8d5"
       },

docs/spec/manifest-v2-2.md

@@ -124,8 +124,8 @@ image manifest based on the Content-Type returned in the HTTP response.
   "manifests": [
     {
       "mediaType": "application/vnd.docker.distribution.manifest.v2+json",
-      "size": 7143,
       "digest": "sha256:e692418e4cbaf90ca69d05a66403747baa33ee08806650b51fab815ad7fc331f",
+      "size": 7143,
       "platform": {
         "architecture": "ppc64le",
         "os": "linux"
@@ -133,8 +133,8 @@ image manifest based on the Content-Type returned in the HTTP response.
     },
     {
       "mediaType": "application/vnd.docker.distribution.manifest.v2+json",
-      "size": 7682,
       "digest": "sha256:5b0bcabd1ed22e9fb1310cf6c2dec7cdef19f0ad69efa1f392e94a4333501270",
+      "size": 7682,
       "platform": {
         "architecture": "amd64",
         "os": "linux",
@@ -232,24 +232,24 @@ image. It's the direct replacement for the schema-1 manifest.
     "mediaType": "application/vnd.docker.distribution.manifest.v2+json",
     "config": {
         "mediaType": "application/vnd.docker.container.image.v1+json",
-        "size": 7023,
+        "digest": "sha256:b5b2b2c507a0944348e0303114d8d93aaaa081732b86451d9bce1f432a537bc7",
-        "digest": "sha256:b5b2b2c507a0944348e0303114d8d93aaaa081732b86451d9bce1f432a537bc7"
+        "size": 7023
     },
     "layers": [
         {
             "mediaType": "application/vnd.docker.image.rootfs.diff.tar.gzip",
-            "size": 32654,
+            "digest": "sha256:e692418e4cbaf90ca69d05a66403747baa33ee08806650b51fab815ad7fc331f",
-            "digest": "sha256:e692418e4cbaf90ca69d05a66403747baa33ee08806650b51fab815ad7fc331f"
+            "size": 32654
         },
         {
             "mediaType": "application/vnd.docker.image.rootfs.diff.tar.gzip",
-            "size": 16724,
+            "digest": "sha256:3c3a4604a545cdc127456d94e421cd355bca5b528f4a9c1905b15da2eb4a4c6b",
-            "digest": "sha256:3c3a4604a545cdc127456d94e421cd355bca5b528f4a9c1905b15da2eb4a4c6b"
+            "size": 16724
         },
         {
             "mediaType": "application/vnd.docker.image.rootfs.diff.tar.gzip",
-            "size": 73109,
+            "digest": "sha256:ec4b8955958665577945c89419d1af06b5f7636b4ac3da7f12184802ad867736",
-            "digest": "sha256:ec4b8955958665577945c89419d1af06b5f7636b4ac3da7f12184802ad867736"
+            "size": 73109
         }
     ]
 }

manifest/manifestlist/manifestlist_test.go

@@ -18,8 +18,8 @@ const expectedManifestListSerialization = `{
    "manifests": [
       {
          "mediaType": "application/vnd.docker.distribution.manifest.v2+json",
-         "size": 985,
          "digest": "sha256:1a9ec845ee94c202b2d5da74a24f0ed2058318bfa9879fa541efaecba272e86b",
+         "size": 985,
          "platform": {
             "architecture": "amd64",
             "os": "linux",
@@ -30,8 +30,8 @@ const expectedManifestListSerialization = `{
       },
       {
          "mediaType": "application/vnd.docker.distribution.manifest.v2+json",
-         "size": 2392,
          "digest": "sha256:6346340964309634683409684360934680934608934608934608934068934608",
+         "size": 2392,
          "platform": {
             "architecture": "sun4m",
             "os": "sunos"
@@ -142,8 +142,8 @@ const expectedOCIImageIndexSerialization = `{
    "manifests": [
       {
          "mediaType": "application/vnd.oci.image.manifest.v1+json",
-         "size": 985,
          "digest": "sha256:1a9ec845ee94c202b2d5da74a24f0ed2058318bfa9879fa541efaecba272e86b",
+         "size": 985,
          "platform": {
             "architecture": "amd64",
             "os": "linux",
@@ -154,8 +154,8 @@ const expectedOCIImageIndexSerialization = `{
       },
       {
          "mediaType": "application/vnd.oci.image.manifest.v1+json",
-         "size": 985,
          "digest": "sha256:1a9ec845ee94c202b2d5da74a24f0ed2058318bfa9879fa541efaecba272e86b",
+         "size": 985,
          "annotations": {
             "platform": "none"
          },
@@ -166,8 +166,8 @@ const expectedOCIImageIndexSerialization = `{
       },
       {
          "mediaType": "application/vnd.oci.image.manifest.v1+json",
-         "size": 2392,
          "digest": "sha256:6346340964309634683409684360934680934608934608934608934068934608",
+         "size": 2392,
          "annotations": {
             "what": "for"
          },

manifest/ocischema/manifest_test.go

@@ -18,8 +18,8 @@ const expectedManifestSerialization = `{
    "mediaType": "application/vnd.oci.image.manifest.v1+json",
    "config": {
       "mediaType": "application/vnd.oci.image.config.v1+json",
-      "size": 985,
       "digest": "sha256:1a9ec845ee94c202b2d5da74a24f0ed2058318bfa9879fa541efaecba272e86b",
+      "size": 985,
       "annotations": {
          "apple": "orange"
       }
@@ -27,8 +27,8 @@ const expectedManifestSerialization = `{
    "layers": [
       {
          "mediaType": "application/vnd.oci.image.layer.v1.tar+gzip",
-         "size": 153263,
          "digest": "sha256:62d8908bee94c202b2d35224a221aaa2058318bfa9879fa541efaecba272331b",
+         "size": 153263,
          "annotations": {
             "lettuce": "wrap"
          }

manifest/schema2/manifest_test.go

@@ -15,14 +15,14 @@ const expectedManifestSerialization = `{
    "mediaType": "application/vnd.docker.distribution.manifest.v2+json",
    "config": {
       "mediaType": "application/vnd.docker.container.image.v1+json",
-      "size": 985,
+      "digest": "sha256:1a9ec845ee94c202b2d5da74a24f0ed2058318bfa9879fa541efaecba272e86b",
-      "digest": "sha256:1a9ec845ee94c202b2d5da74a24f0ed2058318bfa9879fa541efaecba272e86b"
+      "size": 985
    },
    "layers": [
       {
          "mediaType": "application/vnd.docker.image.rootfs.diff.tar.gzip",
-         "size": 153263,
+         "digest": "sha256:62d8908bee94c202b2d35224a221aaa2058318bfa9879fa541efaecba272331b",
-         "digest": "sha256:62d8908bee94c202b2d35224a221aaa2058318bfa9879fa541efaecba272331b"
+         "size": 153263
       }
    ]
 }`

notifications/event_test.go

@@ -22,8 +22,8 @@ func TestEventEnvelopeJSONFormat(t *testing.T) {
          "action": "push",
          "target": {
             "mediaType": "application/vnd.docker.distribution.manifest.v1+prettyjws",
-            "size": 1,
             "digest": "sha256:0123456789abcdef0",
+            "size": 1,
             "length": 1,
             "repository": "library/test",
             "url": "http://example.com/v2/library/test/manifests/latest"
@@ -48,8 +48,8 @@ func TestEventEnvelopeJSONFormat(t *testing.T) {
          "action": "push",
          "target": {
             "mediaType": "application/vnd.docker.container.image.rootfs.diff+x-gtar",
-            "size": 2,
             "digest": "sha256:3b3692957d439ac1928219a83fac91e7bf96c153725526874673ae1f2023f8d5",
+            "size": 2,
             "length": 2,
             "repository": "library/test",
             "url": "http://example.com/v2/library/test/manifests/latest"
@@ -74,8 +74,8 @@ func TestEventEnvelopeJSONFormat(t *testing.T) {
          "action": "push",
          "target": {
             "mediaType": "application/vnd.docker.container.image.rootfs.diff+x-gtar",
-            "size": 3,
             "digest": "sha256:3b3692957d439ac1928219a83fac91e7bf96c153725526874673ae1f2023f8d6",
+            "size": 3,
             "length": 3,
             "repository": "library/test",
             "url": "http://example.com/v2/library/test/manifests/latest"