Remove sensitive information from Celery executor warning (#34954)

airflow/providers/celery/executors/default_celery.py

@@ -132,9 +132,10 @@ def _get_celery_ssl_active() -> bool:
         f"all necessary certs and key ({e})."
     )
 
-if re2.search("rediss?://|amqp://|rpc://", result_backend):
+match_not_recommended_backend = re2.search("rediss?://|amqp://|rpc://", result_backend)
+if match_not_recommended_backend:
     log.warning(
-        "You have configured a result_backend of %s, it is highly recommended "
-        "to use an alternative result_backend (i.e. a database).",
-        result_backend,
+        "You have configured a result_backend using the protocol `%s`,"
+        " it is highly recommended to use an alternative result_backend (i.e. a database).",
+        match_not_recommended_backend.group(0).strip("://"),
     )

tests/providers/celery/executors/test_celery_executor.py

@@ -330,3 +330,19 @@ def test_send_tasks_to_celery_hang(register_signals):
         # multiprocessing.
         results = executor._send_tasks_to_celery(task_tuples_to_send)
         assert results == [(None, None, 1) for _ in task_tuples_to_send]
+
+
+@conf_vars({("celery", "result_backend"): "rediss://test_user:test_password@localhost:6379/0"})
+def test_celery_executor_with_no_recommended_result_backend(caplog):
+    import importlib
+
+    from airflow.providers.celery.executors.default_celery import log
+
+    with caplog.at_level(logging.WARNING, logger=log.name):
+        # reload celery conf to apply the new config
+        importlib.reload(default_celery)
+        assert "test_password" not in caplog.text
+        assert (
+            "You have configured a result_backend using the protocol `rediss`,"
+            " it is highly recommended to use an alternative result_backend (i.e. a database)."
+        ) in caplog.text