feat: introduce JSON schema for metadata format (bazelbuild#1149)

This allows for nice developer ergonomics in the editor, which can now provide autocomplete and error highlighting in metadata.json files, if a $schema property is added.
It also adds a layer of validation for things like required fields in these json documents.

Fixes bazelbuild#1148

.gitignore

@@ -1,2 +1,3 @@
 tools/__pycache__
+tools/node_modules
 /bazel-*

BUILD

@@ -0,0 +1,21 @@
+load("@npm//tools:ajv-cli/package_json.bzl", ajv = "bin")
+
+_METADATA_FILES = glob(["modules/*/metadata.json"])
+
+[
+    ajv.ajv_test(
+        name = "test_metadata." + s.removesuffix("/metadata.json"),
+        args = [
+            "validate",
+            "-s",
+            "$(execpath metadata.schema.json)",
+            "-d",
+            "$(execpath %s)" % s,
+        ],
+        data = [
+            s,
+            "metadata.schema.json",
+        ],
+    )
+    for s in _METADATA_FILES
+]

MODULE.bazel

@@ -4,6 +4,7 @@ module(
     compatibility_level = 1,
 )
 
+bazel_dep(name = "aspect_rules_js", version = "1.34.1")
 bazel_dep(name = "rules_python", version = "0.26.0")
 
 python = use_extension("@rules_python//python/extensions:python.bzl", "python")
@@ -20,3 +21,12 @@ pip.parse(
     requirements_lock = "//tools:requirements_lock.txt",
 )
 use_repo(pip, "pip")
+
+npm = use_extension("@aspect_rules_js//npm:extensions.bzl", "npm", dev_dependency = True)
+
+npm.npm_translate_lock(
+    name = "npm",
+    pnpm_lock = "//tools:pnpm-lock.yaml",
+)
+
+use_repo(npm, "npm")

metadata.schema.json

@@ -0,0 +1,50 @@
+{
+    "$id": "https://github.com/bazelbuild/bazel-central-registry/modules/metadata.schema.json",
+    "title": "Metadata for a Bazel module",
+    "type": "object",
+    "properties": {
+      "$schema": { "type": "string" },
+      "homepage": {"type": "string"},
+      "maintainers": {
+        "description": "Individuals who can be notified when the module requires human attention",
+        "type": "array",
+        "items": {
+          "type": "object",
+          "properties": {
+            "github": {
+              "type": "string",
+              "description": "maintainer's github username"
+            },
+            "email": {
+              "type": "string",
+              "description": "maintainer's email address"
+            },
+            "name": {
+              "type": "string",
+              "description": "maintainer's name"
+            }
+          }
+        }
+      },
+      "repository": {
+        "type": "array",
+        "items": {
+            "description": "repository, typically in the form github:[github org]/[github repo]",
+            "type": "string"
+        }
+      },
+      "versions": {
+        "type": "array",
+        "items": {
+            "description": "semver version",
+            "type": "string"
+        }
+      },
+      "yanked_versions": {
+        "type": "object",
+        "additionalProperties": true
+      }
+    },
+    "additionalProperties": false,
+    "required": ["homepage", "versions"]
+}

modules/rules_nixpkgs_core/metadata.json

@@ -18,5 +18,5 @@
   "versions": [
     "0.10.0"
   ],
-  "yanked_versions": []
+  "yanked_versions": {}
 }

tools/BUILD

@@ -1,6 +1,9 @@
 load("@rules_python//python:defs.bzl", "py_binary", "py_library")
 load("@python_versions//3.11:defs.bzl", compile_pip_requirements_3_11 = "compile_pip_requirements")
 load("@pip//:requirements.bzl", "requirement")
+load("@npm//:defs.bzl", "npm_link_all_packages")
+
+npm_link_all_packages(name = "node_modules")
 
 compile_pip_requirements_3_11(
     name = "requirements",

tools/package.json

@@ -0,0 +1,6 @@
+{
+    "private": true,
+    "devDependencies": {
+      "ajv-cli": "*"
+    }
+}