Clean up PR previews (Qiskit#1697)

Adds a script and action to delete PR previews for closed PRs. See
ce7e3fb for an example.

---------

Co-authored-by: Eric Arellano <[email protected]>

.github/workflows/pr-cleanup.yml

@@ -0,0 +1,34 @@
+# This code is a Qiskit project.
+#
+# (C) Copyright IBM 2024.
+#
+# This code is licensed under the Apache License, Version 2.0. You may
+# obtain a copy of this license in the LICENSE file in the root directory
+# of this source tree or at http://www.apache.org/licenses/LICENSE-2.0.
+#
+# Any modifications or derivative works of this code must retain this
+# copyright notice, and modified files need to carry a notice indicating
+# that they have been altered from the originals.
+
+name: PR preview cleanup
+on:
+  workflow_dispatch:
+  push:
+    branches:
+      - "main"
+
+jobs:
+  preview-cleanup:
+    name: PR preview cleanup
+    runs-on: ubuntu-latest
+    if: github.repository_owner == 'Qiskit'
+    steps:
+      - uses: actions/checkout@v4
+      - uses: actions/setup-python@v5
+        with:
+          python-version: "3.11"
+
+      - name: Clean up PR previews
+        run: scripts/pr_previews/cleanup.py
+        env:
+          GH_TOKEN: ${{ github.token }}

.github/workflows/pr-preview.yml

@@ -52,8 +52,6 @@ jobs:
 
       - name: Deploy to GitHub Pages
         run: scripts/pr_previews/deploy.py ${{ env.PR_PREVIEW_PATH }}
-      - name: Switch back to original branch
-        uses: actions/checkout@v4
 
       - name: Determine deployment result
         run: scripts/pr_previews/poll_deployment.py ${{ env.PR_PREVIEW_URL }}

scripts/pr_previews/cleanup.py

@@ -0,0 +1,64 @@
+#!/usr/bin/env python3
+
+# This code is a Qiskit project.
+#
+# (C) Copyright IBM 2024.
+#
+# This code is licensed under the Apache License, Version 2.0. You may
+# obtain a copy of this license in the LICENSE file in the root directory
+# of this source tree or at http://www.apache.org/licenses/LICENSE-2.0.
+#
+# Any modifications or derivative works of this code must retain this
+# copyright notice, and modified files need to carry a notice indicating
+# that they have been altered from the originals.
+
+import json
+import logging
+import shutil
+from pathlib import Path
+
+logger = logging.getLogger(__name__)
+
+from utils import (
+    configure_logging,
+    run_subprocess,
+    setup_git_account,
+    switch_branch,
+    changed_files,
+    commit_all_and_push,
+)
+
+
+def main() -> None:
+    setup_git_account()
+
+    with switch_branch("gh-pages"):
+        delete_closed_pr_folders()
+
+        if not changed_files():
+            logger.info("No changed files detected, so no push made to gh-pages")
+            return
+
+        commit_all_and_push("Clean up PR previews")
+        logger.info("Pushed updates to gh-pages branch")
+
+
+def get_active_pr_folders() -> set[str]:
+    raw = run_subprocess(
+        ["gh", "pr", "list", "--state", "open", "--json", "number", "--limit", "1000"]
+    ).stdout
+    # `raw` is JSON string of form: { number: int }[]
+    return {f"pr-{obj['number']}" for obj in json.loads(raw)}
+
+
+def delete_closed_pr_folders() -> None:
+    active_pr_folders = get_active_pr_folders()
+    for folder in Path(".").glob("pr-*"):
+        if folder.name not in active_pr_folders:
+            logger.info(f"Deleting {folder}")
+            shutil.rmtree(folder)
+
+
+if __name__ == "__main__":
+    configure_logging()
+    main()

scripts/pr_previews/deploy.py

@@ -19,7 +19,14 @@
 
 logger = logging.getLogger(__name__)
 
-from utils import configure_logging, run_subprocess
+from utils import (
+    configure_logging,
+    run_subprocess,
+    setup_git_account,
+    switch_branch,
+    changed_files,
+    commit_all_and_push,
+)
 
 
 def create_parser() -> ArgumentParser:
@@ -36,33 +43,21 @@ def main() -> None:
         raise AssertionError(
             f"Expected {folder} to have been created with the new content"
         )
-
-    run_subprocess(["git", "config", "user.name", "github-actions[bot]"])
-    run_subprocess(
-        ["git", "config", "user.email", "github-actions[bot]@users.noreply.github.com"]
-    )
-
-    run_subprocess(["git", "fetch", "origin", "gh-pages"])
+    setup_git_account()
 
     # Handle if the content folder already exists on gh-pages branch.
     run_subprocess(["git", "stash", "--include-untracked"])
-    run_subprocess(["git", "switch", "gh-pages"])
-    if folder.exists():
-        shutil.rmtree(folder)
-    run_subprocess(["git", "stash", "pop"])
+    with switch_branch("gh-pages"):
+        if folder.exists():
+            shutil.rmtree(folder)
+        run_subprocess(["git", "stash", "pop"])
 
-    changed_files = run_subprocess(["git", "status", "--porcelain"]).stdout.strip()
-    if changed_files:
-        run_subprocess(["git", "add", "."])
-        run_subprocess(["git", "commit", "-m", f"Deploy PR preview for {folder}"])
-        run_subprocess(["git", "push"])
-        logger.info("Pushed updates to gh-pages branch")
-    else:
-        logger.info("No changed files detected, so no push made to gh-pages")
+        if not changed_files():
+            logger.info("No changed files detected, so no push made to gh-pages")
+            return
 
-    logger.warning(
-        "The branch is set to gh-pages. You probably want to `git switch` back to your original branch"
-    )
+        commit_all_and_push(f"Deploy PR preview for {folder}")
+        logger.info("Pushed updates to gh-pages branch")
 
 
 if __name__ == "__main__":

scripts/pr_previews/utils.py

@@ -14,7 +14,9 @@
 
 import logging
 import subprocess
+from contextlib import contextmanager
 from pathlib import Path
+from typing import Iterator
 
 
 logger = logging.getLogger(__name__)
@@ -28,6 +30,31 @@ def configure_logging() -> None:
     )
 
 
+def setup_git_account() -> None:
+    run_subprocess(["git", "config", "user.name", "github-actions[bot]"])
+    run_subprocess(
+        ["git", "config", "user.email", "github-actions[bot]@users.noreply.github.com"]
+    )
+
+
+def changed_files() -> str:
+    return run_subprocess(["git", "status", "--porcelain"]).stdout.strip()
+
+
+def commit_all_and_push(commit_message: str) -> None:
+    run_subprocess(["git", "add", "."])
+    run_subprocess(["git", "commit", "-m", commit_message])
+    run_subprocess(["git", "push"])
+
+
+@contextmanager
+def switch_branch(branchname: str) -> Iterator[None]:
+    run_subprocess(["git", "fetch", "origin", branchname])
+    run_subprocess(["git", "switch", branchname])
+    yield
+    run_subprocess(["git", "checkout", "-"])
+
+
 def run_subprocess(
     cmd: list[str],
     *,
@@ -52,4 +79,4 @@ def run_subprocess(
     if not stream_output:
         logger.error(f"stdout: {result.stdout}")
         logger.error(f"stderr: {result.stderr}")
-    raise SystemExit()
+    raise SystemExit(1)