refactor: remove templated json generation

oci/private/pull.bzl

@@ -326,23 +326,6 @@ load("@bazel_skylib//rules:write_file.bzl", "write_file")
 
 package(default_visibility = ["//visibility:public"])
 
-# Mimic the output of crane pull [image] layout --format=oci
-write_file(
-    name = "write_layout",
-    out = "oci-layout",
-    content = [
-        "{{",
-        "    \\"imageLayoutVersion\\": \\"1.0.0\\"",
-        "}}",
-    ],
-)
-
-write_file(
-    name = "write_index",
-    out = "index.json",
-    content = [\"\"\"{index_content}\"\"\"],
-)
-
 copy_file(
     name = "manifest",
     src = "manifest.json",
@@ -425,45 +408,39 @@ def _oci_pull_impl(rctx):
         if hash not in tars:
             tars.append(hash)
 
-    # To make testing against `crane pull` simple, we take care to produce a byte-for-byte-identical
-    # index.json file, which means we can't use jq (it produces a trailing newline) or starlark
-    # json.encode_indent (it re-orders keys in the dictionary).
+
+    # create index.json manifest entry
+    index_json_manifest = {
+        "mediaType": image_mf["mediaType"],
+        "size": image_mf_len,
+        "digest": image_digest
+    }
+
     if rctx.attr.platform:
-        os, arch = rctx.attr.platform.split("/", 1)
-        index_mf = """\
-{
-   "schemaVersion": 2,
-   "mediaType": "application/vnd.oci.image.index.v1+json",
-   "manifests": [
-      {
-         "mediaType": "%s",
-         "size": %s,
-         "digest": "%s",
-         "platform": {
-            "architecture": "%s",
-            "os": "%s"
-         }
-      }
-   ]
-}""" % (image_mf["mediaType"], image_mf_len, image_digest, arch, os)
-    else:
-        index_mf = """\
-{
-   "schemaVersion": 2,
-   "mediaType": "application/vnd.oci.image.index.v1+json",
-   "manifests": [
-      {
-         "mediaType": "%s",
-         "size": %s,
-         "digest": "%s"
-      }
-   ]
-}""" % (image_mf["mediaType"], image_mf_len, image_digest)
+        platform_parts = rctx.attr.platform.split("/", 2)
+        index_json_manifest["platform"] = {
+            "os": platform_parts[0],
+            "architecture": platform_parts[1],
+        }
+        # add variant if provided
+        if len(platform_parts) == 3:
+            index_json_manifest["platform"]["variant"] = platform_parts[1]
+
+    # create index.json
+    index_json = {
+        "schemaVersion": 2,
+        "mediaType": "application/vnd.oci.image.index.v1+json",
+        "manifests": [index_json_manifest],
+    }
+    oci_layout = {
+        "imageLayoutVersion": "1.0.0"
+    }
 
+    rctx.file("index.json", json.encode_indent(index_json, indent = "  "))
+    rctx.file("oci-layout", json.encode_indent(oci_layout, indent = "    "))
     rctx.file("BUILD.bazel", content = _build_file.format(
         target_name = rctx.attr.target_name,
         tars = tars,
-        index_content = index_mf,
         image_digest = _trim_hash_algorithm(image_digest),
         config_file = image_config_file,
     ))

oci/tests/BUILD.bazel

@@ -16,7 +16,12 @@ IMAGES_TO_TEST = {
     genrule(
         name = "pull_{}".format(repo_name),
         outs = [repo_name],
-        cmd = "$(CRANE_BIN) pull {reference} $@ --format=oci --platform={platform}".format(
+        cmd = """
+$(CRANE_BIN) pull {reference} $@ --format=oci --platform={platform}
+cat "$@/index.json" | $(JQ_BIN) --sort-keys -j '.' > "$@/index-tmp.json"
+rm "$@/index.json"
+mv "$@/index-tmp.json" "$@/index.json"
+""".format(
             platform = _PLATFORM,
             reference = reference,
         ),
@@ -29,6 +34,7 @@ IMAGES_TO_TEST = {
         tags = ["requires-network"],
         toolchains = [
             "@oci_crane_toolchains//:current_toolchain",
+            "@jq_toolchains//:resolved_toolchain"
         ],
         visibility = ["//visibility:public"],
     )
@@ -62,4 +68,4 @@ build_test(
     ],
 )
 
-parse_image_test(name = "parse_image_test")
+parse_image_test(name = "parse_image_test")