Add a script to update the hook definition with the TAG during release (#507)

Fixes #501, fixed relanding of #491.

.taskcluster.yml

@@ -257,12 +257,15 @@ tasks:
             env:
               GIT_REPOSITORY: ${repository}
               GIT_REVISION: ${head_rev}
+              VERSION: {$eval: 'head_branch[10:]'}
             command:
-              - taskboot
-              - build-hook
-              - infra/taskcluster-hook-pipeline-start.json
-              - project-relman
-              - bugbug
+              - "/bin/sh"
+              - "-lcxe"
+              - "git clone ${repository} &&
+                 cd bugbug &&
+                 git checkout ${head_rev} &&
+                 python infra/set_hook_env_var.py TAG $VERSION infra/taskcluster-hook-pipeline-start.json &&
+                 taskboot --target . build-hook infra/taskcluster-hook-pipeline-start.json project-relman bugbug"
           routes:
             - project.relman.bugbug.deploy_ending
           metadata:
@@ -292,12 +295,15 @@ tasks:
             env:
               GIT_REPOSITORY: ${repository}
               GIT_REVISION: ${head_rev}
+              VERSION: {$eval: 'head_branch[10:]'}
             command:
-              - taskboot
-              - build-hook
-              - infra/taskcluster-hook-check-models-start.json
-              - project-relman
-              - bugbug-checks
+              - "/bin/sh"
+              - "-lcxe"
+              - "git clone ${repository} &&
+                 cd bugbug &&
+                 git checkout ${head_rev} &&
+                 python infra/set_hook_env_var.py TAG $VERSION infra/taskcluster-hook-check-models-start.json &&
+                 taskboot --target . build-hook infra/taskcluster-hook-check-models-start.json project-relman bugbug-checks"
           metadata:
             name: bugbug update check hook
             description: bugbug update check hook

infra/set_hook_env_var.py

@@ -0,0 +1,48 @@
+# -*- coding: utf-8 -*-
+# This Source Code Form is subject to the terms of the Mozilla Public
+# License, v. 2.0. If a copy of the MPL was not distributed with this file,
+# You can obtain one at http://mozilla.org/MPL/2.0/.
+
+import argparse
+import json
+import sys
+
+
+def main(raw_args):
+    parser = argparse.ArgumentParser()
+    parser.add_argument(
+        "env_name",
+        metavar="env-name",
+        type=str,
+        help="The name of the environment variable to set",
+    )
+    parser.add_argument(
+        "env_value",
+        metavar="env-value",
+        type=str,
+        help="The value of the environment variable to set",
+    )
+    parser.add_argument(
+        "hook_file",
+        metavar="hook-file",
+        type=str,
+        help="The hook definition file to update in-place",
+    )
+
+    args = parser.parse_args(raw_args)
+
+    with open(args.hook_file, "r") as hook_file:
+        hook_data = json.load(hook_file)
+
+    # Insert or replace the environment variable
+    hook_env = hook_data["task"]["payload"]["env"]
+    hook_env[args.env_name] = args.env_value
+
+    with open(args.hook_file, "w") as hook_file:
+        json.dump(
+            hook_data, hook_file, sort_keys=True, indent=4, separators=(",", ": ")
+        )
+
+
+if __name__ == "__main__":
+    main(sys.argv[1:])