[airflow] Avoid implicit DAG schedule (AIR301)

[uranusjr]

Summary

Airflow 3.0 changes the default of the 'schedule' argument. This causes incompatibility if a DAG previously does not specify a schedule explicitly. This is against best practice anyway---you should always prefer to set a schedule explicitly.

Due to backward compatibility, Airflow 2 also possesses multiple arguments to set the schedule. These are all being combined into 'schedule' in 3.0. Usages of those old arguments are also detected.

Test Plan

A test fixture has been included for the rule.

[github-actions]

ruff-ecosystem results

Linter (stable)

✅ ecosystem check detected no linter changes.

Linter (preview)

ℹ️ ecosystem check detected linter changes. (+35 -0 violations, +0 -0 fixes in 1 projects; 54 projects unchanged)

apache/airflow (+35 -0 violations, +0 -0 fixes)

ruff check --no-cache --exit-zero --ignore RUF9 --output-format concise --preview --select ALL

+ airflow/models/dag.py:296:16: AIR301 DAG should have an explicit `schedule` argument
+ performance/src/performance_dags/performance_dag/performance_dag.py:230:11: AIR301 DAG should have an explicit `schedule` argument
+ providers/src/airflow/providers/arangodb/example_dags/example_arangodb.py:25:7: AIR301 DAG should have an explicit `schedule` argument
+ providers/src/airflow/providers/google/cloud/example_dags/example_cloud_task.py:41:6: AIR301 DAG should have an explicit `schedule` argument
+ providers/src/airflow/providers/google/cloud/example_dags/example_facebook_ads_to_gcs.py:61:6: AIR301 DAG should have an explicit `schedule` argument
+ providers/src/airflow/providers/google/cloud/example_dags/example_looker.py:31:6: AIR301 DAG should have an explicit `schedule` argument
+ providers/src/airflow/providers/google/cloud/example_dags/example_presto_to_gcs.py:52:6: AIR301 DAG should have an explicit `schedule` argument
+ providers/src/airflow/providers/google/cloud/example_dags/example_salesforce_to_gcs.py:47:6: AIR301 DAG should have an explicit `schedule` argument
+ providers/src/airflow/providers/google/marketing_platform/example_dags/example_display_video.py:124:6: AIR301 DAG should have an explicit `schedule` argument
+ providers/src/airflow/providers/google/marketing_platform/example_dags/example_display_video.py:172:6: AIR301 DAG should have an explicit `schedule` argument
+ providers/src/airflow/providers/google/marketing_platform/example_dags/example_display_video.py:91:6: AIR301 DAG should have an explicit `schedule` argument
+ providers/src/airflow/providers/oracle/example_dags/example_oracle.py:25:6: AIR301 DAG should have an explicit `schedule` argument
+ providers/tests/google/cloud/operators/test_looker.py:47:19: AIR301 DAG should have an explicit `schedule` argument
+ providers/tests/google/cloud/utils/airflow_util.py:54:15: AIR301 DAG should have an explicit `schedule` argument
+ providers/tests/google/cloud/utils/test_mlengine_operator_utils.py:64:12: AIR301 DAG should have an explicit `schedule` argument
+ providers/tests/integration/mongo/sensors/test_mongo.py:49:20: AIR301 DAG should have an explicit `schedule` argument
+ providers/tests/integration/qdrant/operators/test_qdrant_ingest.py:38:20: AIR301 DAG should have an explicit `schedule` argument
+ providers/tests/integration/redis/sensors/test_redis_key.py:35:20: AIR301 DAG should have an explicit `schedule` argument
+ providers/tests/integration/redis/sensors/test_redis_pub_sub.py:38:20: AIR301 DAG should have an explicit `schedule` argument
+ providers/tests/integration/ydb/operators/test_ydb.py:51:20: AIR301 DAG should have an explicit `schedule` argument
+ providers/tests/system/apache/kafka/example_dag_event_listener.py:85:6: AIR301 DAG should have an explicit `schedule` argument
+ providers/tests/system/asana/example_asana.py:49:6: AIR301 DAG should have an explicit `schedule` argument
+ providers/tests/system/google/cloud/cloud_functions/example_functions.py:81:6: AIR301 DAG should have an explicit `schedule` argument
+ task_sdk/tests/dags/super_basic.py:24:2: AIR301 DAG should have an explicit `schedule` argument
+ task_sdk/tests/dags/super_basic_run.py:30:2: AIR301 DAG should have an explicit `schedule` argument
+ task_sdk/tests/defintions/test_baseoperator.py:283:23: AIR301 DAG should have an explicit `schedule` argument
+ task_sdk/tests/defintions/test_baseoperator.py:352:10: AIR301 DAG should have an explicit `schedule` argument
+ task_sdk/tests/defintions/test_baseoperator.py:359:10: AIR301 DAG should have an explicit `schedule` argument
+ task_sdk/tests/defintions/test_dag.py:296:9: AIR301 DAG should have an explicit `schedule` argument
+ task_sdk/tests/defintions/test_dag.py:339:14: AIR301 DAG should have an explicit `schedule` argument
+ task_sdk/tests/defintions/test_dag.py:345:16: AIR301 DAG should have an explicit `schedule` argument
+ tests/jobs/test_scheduler_job.py:6434:16: AIR301 DAG should have an explicit `schedule` argument
+ tests/models/test_dag.py:2855:10: AIR301 DAG should have an explicit `schedule` argument
+ tests/serialization/test_serialized_objects.py:218:47: AIR301 DAG should have an explicit `schedule` argument
+ tests/utils/test_log_handlers.py:273:15: AIR301 DAG should have an explicit `schedule` argument

Changes by rule (1 rules affected)

code	total	+ violation	- violation	+ fix	- fix
AIR301	35	35	0	0	0

[MichaReiser]

This overall looks good to me, but I think we have to figure out the right scoping for all the Airflow3 deprecation rules.

[MichaReiser]

Can we tell a bit more about how it breaks existing DAGS that use the implicit default. Will it fail with an exception or is it just that the default is different?

[uranusjr]

Just the default is different—your DAGs will simply stop doing anything silently. I’ll add a paragraph to call this out.

[MichaReiser]

This is great. Thank you :)