Worker coordination cleanup

src/alpine_bits_python/worker_coordination.py

@@ -21,12 +21,32 @@ class WorkerLock:
     services like schedulers only run on one worker.
     """
 
-    def __init__(self, lock_file: str = "/tmp/alpinebits_primary_worker.lock"):
+    def __init__(self, lock_file: str | None = None):
         """Initialize the worker lock.
 
         Args:
-            lock_file: Path to the lock file
+            lock_file: Path to the lock file. If None, will try /var/run first,
+                      falling back to /tmp if /var/run is not writable.
         """
+        if lock_file is None:
+            # Try /var/run first (more persistent), fall back to /tmp
+            for candidate in ["/var/run/alpinebits_primary_worker.lock",
+                            "/tmp/alpinebits_primary_worker.lock"]:
+                try:
+                    candidate_path = Path(candidate)
+                    candidate_path.parent.mkdir(parents=True, exist_ok=True)
+                    # Test if we can write to this location
+                    test_file = candidate_path.parent / ".alpinebits_test"
+                    test_file.touch()
+                    test_file.unlink()
+                    lock_file = candidate
+                    break
+                except (PermissionError, OSError):
+                    continue
+            else:
+                # If all fail, default to /tmp
+                lock_file = "/tmp/alpinebits_primary_worker.lock"
+
         self.lock_file = Path(lock_file)
         self.lock_fd = None
         self.is_primary = False
@@ -107,6 +127,7 @@ def is_primary_worker() -> tuple[bool, WorkerLock | None]:
     """Determine if this worker should run singleton services.
 
     Uses file-based locking to coordinate between workers.
+    Includes stale lock detection and cleanup.
 
     Returns:
         Tuple of (is_primary, lock_object)
@@ -114,6 +135,31 @@ def is_primary_worker() -> tuple[bool, WorkerLock | None]:
         - lock_object: WorkerLock instance (must be kept alive)
     """
     lock = WorkerLock()
+
+    # Check for stale locks from dead processes
+    if lock.lock_file.exists():
+        try:
+            with open(lock.lock_file, 'r') as f:
+                old_pid_str = f.read().strip()
+                if old_pid_str:
+                    old_pid = int(old_pid_str)
+                    # Check if the process with this PID still exists
+                    try:
+                        os.kill(old_pid, 0)  # Signal 0 just checks existence
+                        _LOGGER.debug("Lock held by active process pid=%d", old_pid)
+                    except ProcessLookupError:
+                        # Process is dead, remove stale lock
+                        _LOGGER.warning(
+                            "Removing stale lock file from dead process pid=%d",
+                            old_pid
+                        )
+                        try:
+                            lock.lock_file.unlink()
+                        except Exception as e:
+                            _LOGGER.warning("Failed to remove stale lock: %s", e)
+        except (ValueError, FileNotFoundError, PermissionError) as e:
+            _LOGGER.warning("Error checking lock file: %s", e)
+
     is_primary = lock.acquire()
 
     return is_primary, lock