Close outdated pulumi-bot PRs automatically (#729)

pulumi-bot opens lots of PRs. Because of the number of repos we
maintain, all PRs that pulumi-bot opens that we want to merge are set to
auto-merge. Other PRs are opened for test purposes, but we don't intend
to merge these. We want to close these PRs after a couple of days to
avoid them cluttering up the repo.

This adds a script (invoked every night on a cron) that cleans up PRs by
`pulumi-bot` that are not set to auto-merge and that are older then 3
days old.

.github/workflows/close-pulumi-bot-prs.yml

@@ -0,0 +1,17 @@
+# This calls close_outdated_bridge_prs.py as part of a daily cron.
+#
+name: Close pulumi-bot PRs
+on:
+  schedule:
+  # 4 AM UTC ~ 9 PM PDT - specifically selected to avoid putting load on the CI system during working hours.
+  - cron: 0 4 * * *
+  workflow_dispatch:
+
+env:
+  GITHUB_TOKEN: ${{ secrets.PULUMI_BOT_TOKEN }}
+jobs:
+  close-outdated-prs:
+    runs-on: ubuntu-latest
+    steps:
+      - uses: actions/checkout@v2
+      - run: ./scripts/close_outdated_bridge_prs.py

scripts/close_outdated_bridge_prs.py

@@ -0,0 +1,77 @@
+#!/usr/bin/env python3
+
+# This script closes pulumi-bot PRs that we will not merge.
+#
+# pulumi-bot opens lots of PRs. Because of the number of repos we maintain, all PRs that
+# pulumi-bot opens that we want to merge are set to auto-merge. Other PRs are opened for
+# test purposes, but we don't intend to merge these. We want to close these PRs after a
+# couple of days to avoid them cluttering up the repo.
+#
+# This script accomplishes that.
+
+import subprocess
+import json
+from datetime import datetime, timedelta
+
+
+def cmd(*args: str, prefix="Exec: ") -> str:
+    print(prefix + " ".join(args))
+    return subprocess.run(args,
+                   capture_output=True,
+                   check=True,
+                   encoding="utf-8").stdout
+
+# PRs that would otherwise be closed are allowed to live for PR_LIFETIME_DAYS after their
+# creation date.
+PR_LIFETIME_DAYS=3
+
+def close_outdated(repo: str):
+    cutoff_date = (datetime.now() - timedelta(days=PR_LIFETIME_DAYS)).date().isoformat()
+    issues = cmd("gh", "pr", "list",
+                 "--repo", repo,
+                 "--json", "author,title,autoMergeRequest,number",
+                 "--search", f"author:pulumi-bot created:<{cutoff_date}",
+                 )
+    # Issues have this shape:
+    #
+    #     {
+    #       "author": {
+    #         "id": "MDQ6VXNlcjMwMzUxOTU1",
+    #         "is_bot": false,
+    #         "login": "pulumi-bot",
+    #         "name": "Pulumi Bot"
+    #       },
+    #       "autoMergeRequest": {
+    #         "authorEmail": null,
+    #         "commitBody": null,
+    #         "commitHeadline": null,
+    #         "mergeMethod": "SQUASH",
+    #         "enabledAt": "2023-11-22T00:23:34Z",
+    #         "enabledBy": {
+    #           "id": "MDQ6VXNlcjMwMzUxOTU1",
+    #           "is_bot": false,
+    #           "login": "pulumi-bot",
+    #           "name": "Pulumi Bot"
+    #         }
+    #       },
+    #       "number": 2204,
+    #       "title": "Upgrade pulumi-terraform-bridge to v3.66.0"
+    #     }
+    #
+    # "autoMergeRequest" may be `null`
+    for issue in json.loads(issues):
+        if issue["autoMergeRequest"] or issue["author"]["login"] != "pulumi-bot":
+            # auto-merge: we don't need to close
+            # non-bot author: not our concern
+            continue
+        issue_title = issue["title"]
+        issue_number = issue["number"]
+        cmd("gh", "pr", "close", str(issue_number), "--repo", repo, prefix=f"Closing \"{issue_title}\":\n\t")
+
+def all_repos() -> [str]:
+    with open("provider-ci/providers.json", "r") as f:
+        return [f"pulumi/pulumi-{p}" for p in json.loads(f.read())]
+
+if __name__ == "__main__":
+    for repo in all_repos():
+        close_outdated(repo)