incubator-airflow/docs/code.rst

API Reference
=============

Operators
---------
Operators allow for generation of certain types of tasks that become nodes in
the DAG when instantiated. All operators derive from ``BaseOperator`` and
inherit many attributes and methods that way. Refer to the BaseOperator_
documentation for more details.

There are 3 main types of operators:

- Operators that performs an **action**, or tell another system to
  perform an action
- **Transfer** operators move data from one system to another
- **Sensors** are a certain type of operator that will keep running until a
  certain criterion is met. Examples include a specific file landing in HDFS or
  S3, a partition appearing in Hive, or a specific time of the day. Sensors
  are derived from ``BaseSensorOperator`` and run a poke
  method at a specified ``poke_interval`` until it returns ``True``.

BaseOperator
''''''''''''
All operators are derived from ``BaseOperator`` and acquire much
functionality through inheritance. Since this is the core of the engine,
it's worth taking the time to understand the parameters of ``BaseOperator``
to understand the primitive features that can be leveraged in your
DAGs.


.. autoclass:: airflow.models.BaseOperator


BaseSensorOperator
'''''''''''''''''''
All sensors are derived from ``BaseSensorOperator``. All sensors inherit
the ``timeout`` and ``poke_interval`` on top of the ``BaseOperator``
attributes.

.. autoclass:: airflow.sensors.base_sensor_operator.BaseSensorOperator


Core Operators
''''''''''''''

Operators
^^^^^^^^^

.. autoclass:: airflow.operators.bash_operator.BashOperator
.. autoclass:: airflow.operators.python_operator.BranchPythonOperator
.. autoclass:: airflow.operators.check_operator.CheckOperator
.. autoclass:: airflow.operators.docker_operator.DockerOperator
.. autoclass:: airflow.operators.dummy_operator.DummyOperator
.. autoclass:: airflow.operators.email_operator.EmailOperator
.. autoclass:: airflow.operators.generic_transfer.GenericTransfer
.. autoclass:: airflow.operators.hive_to_druid.HiveToDruidTransfer
.. autoclass:: airflow.operators.hive_to_mysql.HiveToMySqlTransfer
.. autoclass:: airflow.operators.hive_to_samba_operator.Hive2SambaOperator
.. autoclass:: airflow.operators.hive_operator.HiveOperator
.. autoclass:: airflow.operators.hive_stats_operator.HiveStatsCollectionOperator
.. autoclass:: airflow.operators.check_operator.IntervalCheckOperator
.. autoclass:: airflow.operators.jdbc_operator.JdbcOperator
.. autoclass:: airflow.operators.latest_only_operator.LatestOnlyOperator
.. autoclass:: airflow.operators.mssql_operator.MsSqlOperator
.. autoclass:: airflow.operators.mssql_to_hive.MsSqlToHiveTransfer
.. autoclass:: airflow.operators.mysql_operator.MySqlOperator
.. autoclass:: airflow.operators.mysql_to_hive.MySqlToHiveTransfer
.. autoclass:: airflow.operators.oracle_operator.OracleOperator
.. autoclass:: airflow.operators.pig_operator.PigOperator
.. autoclass:: airflow.operators.postgres_operator.PostgresOperator
.. autoclass:: airflow.operators.presto_check_operator.PrestoCheckOperator
.. autoclass:: airflow.operators.presto_check_operator.PrestoIntervalCheckOperator
.. autoclass:: airflow.operators.presto_to_mysql.PrestoToMySqlTransfer
.. autoclass:: airflow.operators.presto_check_operator.PrestoValueCheckOperator
.. autoclass:: airflow.operators.python_operator.PythonOperator
.. autoclass:: airflow.operators.python_operator.PythonVirtualenvOperator
.. autoclass:: airflow.operators.s3_file_transform_operator.S3FileTransformOperator
.. autoclass:: airflow.operators.s3_to_hive_operator.S3ToHiveTransfer
.. autoclass:: airflow.operators.python_operator.ShortCircuitOperator
.. autoclass:: airflow.operators.http_operator.SimpleHttpOperator
.. autoclass:: airflow.operators.slack_operator.SlackAPIOperator
.. autoclass:: airflow.operators.sqlite_operator.SqliteOperator
.. autoclass:: airflow.operators.subdag_operator.SubDagOperator
.. autoclass:: airflow.operators.dagrun_operator.TriggerDagRunOperator
.. autoclass:: airflow.operators.check_operator.ValueCheckOperator
.. autoclass:: airflow.operators.redshift_to_s3_operator.RedshiftToS3Transfer

Sensors
^^^^^^^
.. autoclass:: airflow.sensors.external_task_sensor.ExternalTaskSensor
.. autoclass:: airflow.sensors.hdfs_sensor.HdfsSensor
.. autoclass:: airflow.sensors.hive_partition_sensor.HivePartitionSensor
.. autoclass:: airflow.sensors.http_sensor.HttpSensor
.. autoclass:: airflow.sensors.metastore_partition_sensor.MetastorePartitionSensor
.. autoclass:: airflow.sensors.named_hive_partition_sensor.NamedHivePartitionSensor
.. autoclass:: airflow.sensors.s3_key_sensor.S3KeySensor
.. autoclass:: airflow.sensors.s3_prefix_sensor.S3PrefixSensor
.. autoclass:: airflow.sensors.sql_sensor.SqlSensor
.. autoclass:: airflow.sensors.time_sensor.TimeSensor
.. autoclass:: airflow.sensors.time_delta_sensor.TimeDeltaSensor
.. autoclass:: airflow.sensors.web_hdfs_sensor.WebHdfsSensor

Community-contributed Operators
'''''''''''''''''''''''''''''''

Operators
^^^^^^^^^

.. autoclass:: airflow.contrib.operators.awsbatch_operator.AWSBatchOperator
.. autoclass:: airflow.contrib.operators.bigquery_check_operator.BigQueryCheckOperator
.. autoclass:: airflow.contrib.operators.bigquery_check_operator.BigQueryValueCheckOperator
.. autoclass:: airflow.contrib.operators.bigquery_check_operator.BigQueryIntervalCheckOperator
.. autoclass:: airflow.contrib.operators.bigquery_get_data.BigQueryGetDataOperator
.. autoclass:: airflow.contrib.operators.bigquery_operator.BigQueryCreateEmptyTableOperator
.. autoclass:: airflow.contrib.operators.bigquery_operator.BigQueryCreateExternalTableOperator
.. autoclass:: airflow.contrib.operators.bigquery_operator.BigQueryOperator
.. autoclass:: airflow.contrib.operators.bigquery_table_delete_operator.BigQueryTableDeleteOperator
.. autoclass:: airflow.contrib.operators.bigquery_to_bigquery.BigQueryToBigQueryOperator
.. autoclass:: airflow.contrib.operators.bigquery_to_gcs.BigQueryToCloudStorageOperator
.. autoclass:: airflow.contrib.operators.databricks_operator.DatabricksSubmitRunOperator
.. autoclass:: airflow.contrib.operators.dataflow_operator.DataFlowJavaOperator
.. autoclass:: airflow.contrib.operators.dataflow_operator.DataflowTemplateOperator
.. autoclass:: airflow.contrib.operators.dataflow_operator.DataFlowPythonOperator
.. autoclass:: airflow.contrib.operators.dataproc_operator.DataprocClusterCreateOperator
.. autoclass:: airflow.contrib.operators.dataproc_operator.DataprocClusterDeleteOperator
.. autoclass:: airflow.contrib.operators.dataproc_operator.DataProcPigOperator
.. autoclass:: airflow.contrib.operators.dataproc_operator.DataProcHiveOperator
.. autoclass:: airflow.contrib.operators.dataproc_operator.DataProcSparkSqlOperator
.. autoclass:: airflow.contrib.operators.dataproc_operator.DataProcSparkOperator
.. autoclass:: airflow.contrib.operators.dataproc_operator.DataProcHadoopOperator
.. autoclass:: airflow.contrib.operators.dataproc_operator.DataProcPySparkOperator
.. autoclass:: airflow.contrib.operators.dataproc_operator.DataprocWorkflowTemplateInstantiateOperator
.. autoclass:: airflow.contrib.operators.dataproc_operator.DataprocWorkflowTemplateInstantiateInlineOperator
.. autoclass:: airflow.contrib.operators.datastore_export_operator.DatastoreExportOperator
.. autoclass:: airflow.contrib.operators.datastore_import_operator.DatastoreImportOperator
.. autoclass:: airflow.contrib.operators.discord_webhook_operator.DiscordWebhookOperator
.. autoclass:: airflow.contrib.operators.druid_operator.DruidOperator
.. autoclass:: airflow.contrib.operators.ecs_operator.ECSOperator
.. autoclass:: airflow.contrib.operators.emr_add_steps_operator.EmrAddStepsOperator
.. autoclass:: airflow.contrib.operators.emr_create_job_flow_operator.EmrCreateJobFlowOperator
.. autoclass:: airflow.contrib.operators.emr_terminate_job_flow_operator.EmrTerminateJobFlowOperator
.. autoclass:: airflow.contrib.operators.file_to_gcs.FileToGoogleCloudStorageOperator
.. autoclass:: airflow.contrib.operators.file_to_wasb.FileToWasbOperator
.. autoclass:: airflow.contrib.operators.gcs_copy_operator.GoogleCloudStorageCopyOperator
.. autoclass:: airflow.contrib.operators.gcs_download_operator.GoogleCloudStorageDownloadOperator
.. autoclass:: airflow.contrib.operators.gcs_list_operator.GoogleCloudStorageListOperator
.. autoclass:: airflow.contrib.operators.gcs_operator.GoogleCloudStorageCreateBucketOperator
.. autoclass:: airflow.contrib.operators.gcs_to_bq.GoogleCloudStorageToBigQueryOperator
.. autoclass:: airflow.contrib.operators.gcs_to_gcs.GoogleCloudStorageToGoogleCloudStorageOperator
.. autoclass:: airflow.contrib.operators.hipchat_operator.HipChatAPIOperator
.. autoclass:: airflow.contrib.operators.hipchat_operator.HipChatAPISendRoomNotificationOperator
.. autoclass:: airflow.contrib.operators.hive_to_dynamodb.HiveToDynamoDBTransferOperator
.. autoclass:: airflow.contrib.operators.jira_operator.JiraOperator
.. autoclass:: airflow.contrib.operators.kubernetes_pod_operator.KubernetesPodOperator
.. autoclass:: airflow.contrib.operators.mlengine_operator.MLEngineBatchPredictionOperator
.. autoclass:: airflow.contrib.operators.mlengine_operator.MLEngineModelOperator
.. autoclass:: airflow.contrib.operators.mlengine_operator.MLEngineVersionOperator
.. autoclass:: airflow.contrib.operators.mlengine_operator.MLEngineTrainingOperator
.. autoclass:: airflow.contrib.operators.mysql_to_gcs.MySqlToGoogleCloudStorageOperator
.. autoclass:: airflow.contrib.operators.postgres_to_gcs_operator.PostgresToGoogleCloudStorageOperator
.. autoclass:: airflow.contrib.operators.pubsub_operator.PubSubTopicCreateOperator
.. autoclass:: airflow.contrib.operators.pubsub_operator.PubSubTopicDeleteOperator
.. autoclass:: airflow.contrib.operators.pubsub_operator.PubSubSubscriptionCreateOperator
.. autoclass:: airflow.contrib.operators.pubsub_operator.PubSubSubscriptionDeleteOperator
.. autoclass:: airflow.contrib.operators.pubsub_operator.PubSubPublishOperator
.. autoclass:: airflow.contrib.operators.qubole_operator.QuboleOperator
.. autoclass:: airflow.contrib.operators.sftp_operator.SFTPOperator
.. autoclass:: airflow.contrib.operators.spark_jdbc_operator.SparkJDBCOperator
.. autoclass:: airflow.contrib.operators.spark_sql_operator.SparkSqlOperator
.. autoclass:: airflow.contrib.operators.spark_submit_operator.SparkSubmitOperator
.. autoclass:: airflow.contrib.operators.sqoop_operator.SqoopOperator
.. autoclass:: airflow.contrib.operators.ssh_operator.SSHOperator
.. autoclass:: airflow.contrib.operators.vertica_operator.VerticaOperator
.. autoclass:: airflow.contrib.operators.spark_submit_operator.SparkSubmitOperator
.. autoclass:: airflow.contrib.operators.vertica_to_hive.VerticaToHiveTransfer

Sensors
^^^^^^^

.. autoclass:: airflow.contrib.sensors.aws_redshift_cluster_sensor.AwsRedshiftClusterSensor
.. autoclass:: airflow.contrib.sensors.bash_sensor.BashSensor
.. autoclass:: airflow.contrib.sensors.bigquery_sensor.BigQueryTableSensor
.. autoclass:: airflow.contrib.sensors.datadog_sensor.DatadogSensor
.. autoclass:: airflow.contrib.sensors.emr_base_sensor.EmrBaseSensor
.. autoclass:: airflow.contrib.sensors.emr_job_flow_sensor.EmrJobFlowSensor
.. autoclass:: airflow.contrib.sensors.emr_step_sensor.EmrStepSensor
.. autoclass:: airflow.contrib.sensors.file_sensor.FileSensor
.. autoclass:: airflow.contrib.sensors.ftp_sensor.FTPSensor
.. autoclass:: airflow.contrib.sensors.ftp_sensor.FTPSSensor
.. autoclass:: airflow.contrib.sensors.gcs_sensor.GoogleCloudStorageObjectSensor
.. autoclass:: airflow.contrib.sensors.gcs_sensor.GoogleCloudStorageObjectUpdatedSensor
.. autoclass:: airflow.contrib.sensors.gcs_sensor.GoogleCloudStoragePrefixSensor
.. autoclass:: airflow.contrib.sensors.hdfs_sensor.HdfsSensorFolder
.. autoclass:: airflow.contrib.sensors.hdfs_sensor.HdfsSensorRegex
.. autoclass:: airflow.contrib.sensors.jira_sensor.JiraSensor
.. autoclass:: airflow.contrib.sensors.pubsub_sensor.PubSubPullSensor
.. autoclass:: airflow.contrib.sensors.qubole_sensor.QuboleSensor
.. autoclass:: airflow.contrib.sensors.redis_key_sensor.RedisKeySensor
.. autoclass:: airflow.contrib.sensors.wasb_sensor.WasbBlobSensor

.. _macros:

Macros
---------
Here's a list of variables and macros that can be used in templates


Default Variables
'''''''''''''''''
The Airflow engine passes a few variables by default that are accessible
in all templates

=================================   ====================================
Variable                            Description
=================================   ====================================
``{{ ds }}``                        the execution date as ``YYYY-MM-DD``
``{{ ds_nodash }}``                 the execution date as ``YYYYMMDD``
``{{ yesterday_ds }}``              yesterday's date as ``YYYY-MM-DD``
``{{ yesterday_ds_nodash }}``       yesterday's date as ``YYYYMMDD``
``{{ tomorrow_ds }}``               tomorrow's date as ``YYYY-MM-DD``
``{{ tomorrow_ds_nodash }}``        tomorrow's date as ``YYYYMMDD``
``{{ ts }}``                        same as ``execution_date.isoformat()``
``{{ ts_nodash }}``                 same as ``ts`` without ``-`` and ``:``
``{{ execution_date }}``            the execution_date, (datetime.datetime)
``{{ prev_execution_date }}``       the previous execution date (if available) (datetime.datetime)
``{{ next_execution_date }}``       the next execution date (datetime.datetime)
``{{ dag }}``                       the DAG object
``{{ task }}``                      the Task object
``{{ macros }}``                    a reference to the macros package, described below
``{{ task_instance }}``             the task_instance object
``{{ end_date }}``                  same as ``{{ ds }}``
``{{ latest_date }}``               same as ``{{ ds }}``
``{{ ti }}``                        same as ``{{ task_instance }}``
``{{ params }}``                    a reference to the user-defined params dictionary
``{{ var.value.my_var }}``          global defined variables represented as a dictionary
``{{ var.json.my_var.path }}``      global defined variables represented as a dictionary
                                    with deserialized JSON object, append the path to the
                                    key within the JSON object
``{{ task_instance_key_str }}``     a unique, human-readable key to the task instance
                                    formatted ``{dag_id}_{task_id}_{ds}``
``{{ conf }}``                      the full configuration object located at
                                    ``airflow.configuration.conf`` which
                                    represents the content of your
                                    ``airflow.cfg``
``{{ run_id }}``                    the ``run_id`` of the current DAG run
``{{ dag_run }}``                   a reference to the DagRun object
``{{ test_mode }}``                 whether the task instance was called using
                                    the CLI's test subcommand
=================================   ====================================

Note that you can access the object's attributes and methods with simple
dot notation. Here are some examples of what is possible:
``{{ task.owner }}``, ``{{ task.task_id }}``, ``{{ ti.hostname }}``, ...
Refer to the models documentation for more information on the objects'
attributes and methods.

The ``var`` template variable allows you to access variables defined in Airflow's
UI. You can access them as either plain-text or JSON. If you use JSON, you are
also able to walk nested structures, such as dictionaries like:
``{{ var.json.my_dict_var.key1 }}``

Macros
''''''
Macros are a way to expose objects to your templates and live under the
``macros`` namespace in your templates.

A few commonly used libraries and methods are made available.


=================================   ====================================
Variable                            Description
=================================   ====================================
``macros.datetime``                 The standard lib's ``datetime.datetime``
``macros.timedelta``                 The standard lib's ``datetime.timedelta``
``macros.dateutil``                 A reference to the ``dateutil`` package
``macros.time``                     The standard lib's ``time``
``macros.uuid``                     The standard lib's ``uuid``
``macros.random``                   The standard lib's ``random``
=================================   ====================================


Some airflow specific macros are also defined:

.. automodule:: airflow.macros
    :show-inheritance:
    :members:

.. autofunction:: airflow.macros.hive.closest_ds_partition
.. autofunction:: airflow.macros.hive.max_partition

.. _models_ref:

Models
------

Models are built on top of the SQLAlchemy ORM Base class, and instances are
persisted in the database.


.. automodule:: airflow.models
    :show-inheritance:
    :members: DAG, BaseOperator, TaskInstance, DagBag, Connection

Hooks
-----

Hooks are interfaces to external platforms and databases, implementing a common
interface when possible and acting as building blocks for operators.

.. autoclass:: airflow.hooks.dbapi_hook.DbApiHook
.. autoclass:: airflow.hooks.docker_hook.DockerHook
.. automodule:: airflow.hooks.hive_hooks
    :members:
      HiveCliHook,
      HiveMetastoreHook,
      HiveServer2Hook
.. autoclass:: airflow.hooks.http_hook.HttpHook
.. autoclass:: airflow.hooks.druid_hook.DruidDbApiHook
.. autoclass:: airflow.hooks.druid_hook.DruidHook
.. autoclass:: airflow.hooks.jdbc_hook.JdbcHook
.. autoclass:: airflow.hooks.mssql_hook.MsSqlHook
.. autoclass:: airflow.hooks.mysql_hook.MySqlHook
.. autoclass:: airflow.hooks.postgres_hook.PostgresHook
.. autoclass:: airflow.hooks.presto_hook.PrestoHook
.. autoclass:: airflow.hooks.S3_hook.S3Hook
.. autoclass:: airflow.hooks.sqlite_hook.SqliteHook
.. autoclass:: airflow.hooks.webhdfs_hook.WebHDFSHook

Community contributed hooks
'''''''''''''''''''''''''''

.. autoclass:: airflow.contrib.hooks.redshift_hook.RedshiftHook
.. autoclass:: airflow.contrib.hooks.bigquery_hook.BigQueryHook
.. autoclass:: airflow.contrib.hooks.vertica_hook.VerticaHook
.. autoclass:: airflow.contrib.hooks.ftp_hook.FTPHook
.. autoclass:: airflow.contrib.hooks.ssh_hook.SSHHook
.. autoclass:: airflow.contrib.hooks.sftp_hook.SFTPHook
.. autoclass:: airflow.contrib.hooks.cloudant_hook.CloudantHook
.. autoclass:: airflow.contrib.hooks.gcs_hook.GoogleCloudStorageHook
.. autoclass:: airflow.contrib.hooks.gcp_pubsub_hook.PubSubHook
.. autoclass:: airflow.contrib.hooks.discord_webhook_hook.DiscordWebhookHook

Executors
---------
Executors are the mechanism by which task instances get run.

.. autoclass:: airflow.executors.local_executor.LocalExecutor
.. autoclass:: airflow.executors.celery_executor.CeleryExecutor
.. autoclass:: airflow.executors.sequential_executor.SequentialExecutor

Community-contributed executors
'''''''''''''''''''''''''''''''

.. autoclass:: airflow.contrib.executors.mesos_executor.MesosExecutor