resolve_xcom_backend ( ) ¶ Resolves custom XCom class. Unnecessary request or other resource consuming operations whenĬreating XCom orm model. From left to right, The key is the identifier of your XCom. You can think of an XCom as a little object with the following fields: that is stored IN the metadata database of Airflow. This method should be overridden in custom XCom backends to avoid Yes XComs What is an Airflow XCom XCom stands for cross-communication and allows to exchange messages or small amount of data between tasks. Serialize Xcom value to str or pickled object static deserialize_value ( result : ‘XCom’ ) ¶ĭeserialize XCom value from str or pickle object orm_deserialize_value ( self ) ¶ĭeserialize method which is used to reconstruct ORM XCom object. XCom objects can be quite big and you might want to limit theĬlassmethod delete ( cls, xcoms, session = None ) ¶ĭelete Xcom static serialize_value ( value : Any ) ¶ Limit ( int) – If required, limit the number of returned objects. Include_prior_dates ( bool) – If False, only XComs from the currentĮxecution_date are returned. Task_ids ( str or iterable of strings ( representing task_ids )) – Only XComs from tasks with matching ids will beĭag_ids ( str) – If provided, only pulls XComs from this DAG. Session ( ) – database sessionĬlassmethod get_many ( cls, execution_date : pendulum.DateTime, key : Optional = None, task_ids : Optional ] ] = None, dag_ids : Optional ] ] = None, include_prior_dates : bool = False, limit : Optional = None, session : Session = None ) ¶Ĭomposes a query to get one or more values from the xcom table. Include_prior_dates ( bool) – If False, only XCom from the currentĮxecution_date are returned. If None (default), the DAG of the calling task is used. Can pass None to remove the filter.ĭag_id ( str) – If provided, only pulls XCom from this DAG. Task_id ( str) – Only XComs from task with matching id will be Returns NoneĮxecution_date ( pendulum.datetime) – Execution date for the task Retrieve an XCom value, optionally meeting certain criteria. As it turns out, you can use a made up task id and it will save it to the xcom table under that id. xcompush and xcompull both just call class methods on XCom.
I was able to come up with a workaround however. None classmethod get_one ( cls, execution_date : pendulum.DateTime, key : Optional = None, task_id : Optional ] ] = None, dag_id : Optional ] ] = None, include_prior_dates : bool = False, session : Session = None ) ¶ 2 Answers Sorted by: 7 Yong Wang's answer explains really well why I wasn't able to get the values I wanted. _repr_ ( self ) ¶ classmethod set ( cls, key, value, execution_date, task_id, dag_id, session = None ) ¶ I.e automatically deserialize Xcom value when loading from DB. _tablename_ = xcom ¶ key ¶ value ¶ timestamp ¶ execution_date ¶ task_id ¶ dag_id ¶ init_on_load ( self ) ¶Ĭalled by the ORM after the instance has been loaded from the DB or otherwise reconstituted BaseXCom ¶īases:, _mixin.LoggingMixinīase class for XCom objects. With this, your virtualenv won't be discarded but newer dependencies will be eventually installed by the Operator.Module Contents ¶. Naturally, you can get rid of the try-finally in ReusableTemporaryDirectory and put back the usual suffix and dir arguments, I made minimal changes to make it easy to compare with the original TemporaryDirectory class. With ReusableTemporaryDirectory(prefix='cached-venv') as tmp_dir: You can subclass PythonVirtualenvOperator and simply use your own context manager that reuses temporary directories: import ReusableTemporaryDirectory(prefix):Įxisting = glob.glob('/tmp/' + prefix + '*') So it looks like it doesn't delete the virtualenv explicitly (it relies on TemporaryDirectory to do that). Return self._read_result(output_filename) With TemporaryDirectory(prefix='venv') as tmp_dir:
#Airflow xcom delete code#
Push return code from bash operator to XCom. Push and pull from other Airflow Operator than pythonOperator. Airflow Push and pull same ID from several operator.
Reading the implementation of PythonVirtualenvOperator's execution method: def execute_callable(self): Learning Airflow XCom is no trivial, So here are some examples based on use cases I have personaly tested: Basic push/pull example based on official example. Implementing a "virtualenv cache" shouldn't be difficult. Or, you can let the Operator create the environment and subsequent operators may reuse it - which is, I believe, the easiest and most dangerous approach. If you use a PythonOperator then only run very very simple code, that must only do simple IO operations (like transform a small XCOM), otherwise run your job. That being said, it's not as much of a big deal, just like you have to preinstall packages to the global environment you can pre-bake a few environments. You operators should be portable, so using longstanding virtualenvs is somewhat against that principle. First things first: you should not (in general) rely on pre-existing resources for your Operators.
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