CMS: Move and rewrite check_unlocked_replicas

cms/check_unlocked_replicas

@@ -0,0 +1,62 @@
+#!/usr/bin/env python3
+# Copyright European Organization for Nuclear Research (CERN) since 2012
+#
+# Licensed under the Apache License, Version 2.0 (the "License");
+# you may not use this file except in compliance with the License.
+# You may obtain a copy of the License at
+#
+#    http://www.apache.org/licenses/LICENSE-2.0
+#
+# Unless required by applicable law or agreed to in writing, software
+# distributed under the License is distributed on an "AS IS" BASIS,
+# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+# See the License for the specific language governing permissions and
+# limitations under the License.
+
+"""
+Probe to check the backlog of unlocked replicas.
+"""
+
+import sys
+from datetime import datetime
+import traceback
+from sqlalchemy import func, select, null, and_
+
+from rucio.db.sqla import models
+from rucio.db.sqla.session import get_session
+
+from utils.common import PrometheusPusher
+
+# Exit statuses
+OK, WARNING, CRITICAL, UNKNOWN = 0, 1, 2, 3
+
+if __name__ == "__main__":
+    try:
+        session = get_session()
+        base_statement =  select(
+            func.count()
+        ).select_from(
+            models.RSEFileAssociation
+        )
+        # Expired replicas 
+        statement = base_statement.where(
+            and_(
+                models.RSEFileAssociation.tombstone != null(),
+                models.RSEFileAssociation.tombstone < datetime.utcnow()
+            )
+        )
+        expired_replicas = session.execute(statement).scalar_one()
+
+        # Unlocked replicas
+        statement = base_statement.where(
+            models.RSEFileAssociation.tombstone != null()
+        )
+        unlocked_replicas = session.execute(statement).scalar_one()
+
+        with PrometheusPusher() as manager:
+            manager.gauge("reaper.expired_replicas").set(expired_replicas)
+            manager.gauge("reaper.unlocked_replicas").set(unlocked_replicas)
+    except Exception:
+        print(traceback.format_exc())
+        sys.exit(UNKNOWN)
+    sys.exit(OK)