lock: allows global lock to be used from main app (PROJQUAY-788) (#745)

GlobalLock had a dependency on app, which would cause a circular
dependency if imported from the main app. Workaround this by requiring
to pass the configuration to the GlobalLock instead (this is done by a
classmethod, due to the use of Redlock's factory). This means before
the use of GlobalLock, "configure" will need to be called once, per process.

util/locking.py

@@ -3,8 +3,6 @@ import logging
 from redis import RedisError
 from redlock import RedLockFactory, RedLockError
 
-from app import app
-
 logger = logging.getLogger(__name__)
 
 
@@ -14,6 +12,19 @@ class LockNotAcquiredException(Exception):
     """
 
 
+def _redlock_factory(config):
+    _redis_info = dict(config["USER_EVENTS_REDIS"])
+    _redis_info.update(
+        {
+            "socket_connect_timeout": 5,
+            "socket_timeout": 5,
+            "single_connection_client": True,
+        }
+    )
+    lock_factory = RedLockFactory(connection_details=[_redis_info])
+    return lock_factory
+
+
 # TODO(kleesc): GlobalLock should either renew the lock until the caller is done,
 # or signal that it is no longer valid to the caller. Currently, GlobalLock will
 # just silently expire the redis key, making the lock available again while any
@@ -28,21 +39,15 @@ class GlobalLock(object):
 
     lock_factory = None
 
-    def __new__(cls, *args, **kwargs):
+    @classmethod
+    def configure(cls, config):
         if cls.lock_factory is None:
-            _redis_info = dict(app.config["USER_EVENTS_REDIS"])
+            cls.lock_factory = _redlock_factory(config)
-            _redis_info.update(
-                {
-                    "socket_connect_timeout": 5,
-                    "socket_timeout": 5,
-                    "single_connection_client": True,
-                }
-            )
-
-            cls.lock_factory = RedLockFactory(connection_details=[_redis_info])
-        return super(GlobalLock, cls).__new__(cls, *args, **kwargs)
 
     def __init__(self, name, lock_ttl=600):
+        if GlobalLock.lock_factory is None:
+            raise LockNotAcquiredException("GlobalLock not configured")
+
         self._lock_name = name
         self._lock_ttl = lock_ttl
         self._redlock = None

workers/blobuploadcleanupworker/blobuploadcleanupworker.py

@@ -86,5 +86,6 @@ def create_gunicorn_worker():
 
 if __name__ == "__main__":
     logging.config.fileConfig(logfile_path(debug=False), disable_existing_loggers=False)
+    GlobalLock.configure(app.config)
     worker = BlobUploadCleanupWorker()
     worker.start()

workers/gc/gcworker.py

@@ -91,5 +91,6 @@ if __name__ == "__main__":
         while True:
             time.sleep(100000)
 
+    GlobalLock.configure(app.config)
     worker = GarbageCollectionWorker()
     worker.start()

workers/globalpromstats/globalpromstats.py

@@ -87,6 +87,7 @@ def main():
         while True:
             time.sleep(100000)
 
+    GlobalLock.configure(app.config)
     worker = GlobalPrometheusStatsWorker()
     worker.start()
 

workers/logrotateworker.py

@@ -153,6 +153,7 @@ def main():
         while True:
             time.sleep(100000)
 
+    GlobalLock.configure(app.config)
     worker = LogRotateWorker()
     worker.start()
 

workers/namespacegcworker.py

@@ -69,6 +69,7 @@ if __name__ == "__main__":
         while True:
             time.sleep(100000)
 
+    GlobalLock.configure(app.config)
     logger.debug("Starting namespace GC worker")
     worker = NamespaceGCWorker(
         namespace_gc_queue,

workers/repositorygcworker.py

@@ -78,6 +78,7 @@ if __name__ == "__main__":
         while True:
             time.sleep(100000)
 
+    GlobalLock.configure(app.config)
     logger.debug("Starting repository GC worker")
     worker = RepositoryGCWorker(
         repository_gc_queue,