Reduce database accesses

No need to check secret variables for every operator, making the
mount_variables variable global to cache it

dags/synaptor_ops.py

@@ -19,6 +19,16 @@
 
 airflow_broker_url = conf.get("celery", "broker_url")
 
+maybe_aws = Variable.get("aws-secret.json", None)
+maybe_gcp = Variable.get("google-secret.json", None)
+
+mount_variables = ["synaptor_param.json"]
+
+if maybe_aws is not None:
+    mount_variables.append("aws-secret.json")
+if maybe_gcp is not None:
+    mount_variables.append("google-secret.json")
+
 # hard-coding these for now
 MOUNT_POINT = "/root/.cloudvolume/secrets/"
 TASK_QUEUE_NAME = "synaptor"
@@ -204,11 +214,8 @@ def manager_op(
     config_path = os.path.join(MOUNT_POINT, "synaptor_param.json")
     command = f"{synaptor_task_name} {config_path}"
 
-    # these variables will be mounted in the containers
-    variables = ["synaptor_param.json"]
-
     return worker_op(
-        variables=variables,
+        variables=mount_variables,
         mount_point=MOUNT_POINT,
         task_id=synaptor_task_name,
         command=command,
@@ -243,12 +250,10 @@ def generate_op(
         command += f" --clusterkey {tag}"
 
     # these variables will be mounted in the containers
-    variables = add_secrets_if_defined(["synaptor_param.json"])
-
     task_id = f"generate_{taskname}" if tag is None else f"generate_{taskname}_{tag}"
 
     return worker_op(
-        variables=variables,
+        variables=mount_variables,
         mount_point=MOUNT_POINT,
         task_id=task_id,
         command=command,
@@ -282,13 +287,10 @@ def synaptor_op(
         " --lease_seconds 300"
     )
 
-    # these variables will be mounted in the containers
-    variables = add_secrets_if_defined(["synaptor_param.json"])
-
     task_id = f"worker_{i}" if tag is None else f"worker_{tag}_{i}"
 
     return worker_op(
-        variables=variables,
+        variables=mount_variables,
         mount_point=MOUNT_POINT,
         task_id=task_id,
         command=command,
@@ -321,21 +323,3 @@ def wait_op(dag: DAG, taskname: str) -> PythonOperator:
         queue="manager",
         dag=dag,
     )
-
-
-# Helper functions
-def add_secrets_if_defined(variables: list[str]) -> list[str]:
-    """Adds CloudVolume secret files to the mounted variables if defined.
-
-    Synaptor still needs to store the google-secret.json file sometimes
-    bc it currently uses an old version of gsutil.
-    """
-    maybe_aws = Variable.get("aws-secret.json", None)
-    maybe_gcp = Variable.get("google-secret.json", None)
-
-    if maybe_aws is not None:
-        variables.append("aws-secret.json")
-    if maybe_gcp is not None:
-        variables.append("google-secret.json")
-
-    return variables