Prepare rollback-safe legacy migration data contract (#7)

2026-09-09 21:42:41 +00:00
parent 2d1964106b
commit 38e87678e1
10 changed files with 289 additions and 2 deletions
@@ -0,0 +1,60 @@
+"""Keep outbound Celery work paused during a verified cold-data migration.
+
+The operator creates the hold file in the candidate data clone before startup
+and removes it only after committing the verified deployment. Normal startups
+without a hold file behave unchanged. This does not pause an existing worker.
+"""
+
+import os
+import stat
+import sys
+import time
+from pathlib import Path
+
+HOLD_FILE = Path("/app/local/.migration-worker-hold")
+COMMANDS = {
+    "worker": [
+        "/app/.venv/bin/celery",
+        "-A",
+        "config",
+        "worker",
+        "-l",
+        "INFO",
+        "-Q",
+        "high,default,low",
+        "--concurrency=2",
+    ],
+    "scheduler": [
+        "/app/.venv/bin/celery",
+        "-A",
+        "config",
+        "beat",
+        "-l",
+        "INFO",
+        "--schedule",
+        "/tmp/celerybeat-schedule",  # noqa: S108 - existing supervised container-local schedule path
+    ],
+}
+
+
+def hold_active(path=HOLD_FILE):
+    try:
+        mode = path.lstat().st_mode
+    except FileNotFoundError:
+        return False
+    if not stat.S_ISREG(mode):
+        raise RuntimeError("Migration hold must be a regular file")
+    return True
+
+
+def start(role, *, check=hold_active, sleep=time.sleep, execute=os.execv):
+    if role not in COMMANDS:
+        raise ValueError("Unsupported supervised process")
+    while check():
+        sleep(1)
+    command = COMMANDS[role]
+    execute(command[0], command)
+
+
+if __name__ == "__main__":
+    start(sys.argv[1] if len(sys.argv) == 2 else "")