docs-archive/apache-airflow/2.0.0/_sources/python-api-ref.rst.txt

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Python API Reference
====================

.. _pythonapi:operators:

Operators
---------
Operators allow for generation of certain types of tasks that become nodes in
the DAG when instantiated. All operators derive from :class:`~airflow.models.BaseOperator` and
inherit many attributes and methods that way.

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 :class:`~airflow.sensors.base.BaseSensorOperator` and run a poke
  method at a specified :attr:`~airflow.sensors.base.BaseSensorOperator.poke_interval` until it returns ``True``.

BaseOperator
''''''''''''
All operators are derived from :class:`~airflow.models.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 :class:`~airflow.models.BaseOperator`
to understand the primitive features that can be leveraged in your
DAGs.

BaseSensorOperator
''''''''''''''''''
All sensors are derived from :class:`~airflow.sensors.base.BaseSensorOperator`. All sensors inherit
the :attr:`~airflow.sensors.base.BaseSensorOperator.timeout` and :attr:`~airflow.sensors.base.BaseSensorOperator.poke_interval` on top of the :class:`~airflow.models.BaseOperator`
attributes.

Operators packages
''''''''''''''''''
All operators are in the following packages:

.. toctree::
  :includehidden:
  :glob:
  :maxdepth: 1

  _api/airflow/operators/index

  _api/airflow/sensors/index


.. _pythonapi:hooks:

Hooks
-----
Hooks are interfaces to external platforms and databases, implementing a common
interface when possible and acting as building blocks for operators. All hooks
are derived from :class:`~airflow.hooks.base.BaseHook`.

Hooks packages
''''''''''''''
All hooks are in the following packages:

.. toctree::
  :includehidden:
  :glob:
  :maxdepth: 1

  _api/airflow/hooks/index

Executors
---------
Executors are the mechanism by which task instances get run. All executors are
derived from :class:`~airflow.executors.base_executor.BaseExecutor`.

Executors packages
''''''''''''''''''
All executors are in the following packages:

.. toctree::
  :includehidden:
  :glob:
  :maxdepth: 1

  _api/airflow/executors/index

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

.. toctree::
  :includehidden:
  :glob:
  :maxdepth: 1

  _api/airflow/models/index

.. _pythonapi:exceptions:

Exceptions
----------

.. toctree::
  :includehidden:
  :glob:
  :maxdepth: 1

  _api/airflow/exceptions/index

Secrets Backends
----------------
Airflow relies on secrets backends to retrieve :class:`~airflow.models.connection.Connection` objects.
All secrets backends derive from :class:`~airflow.secrets.BaseSecretsBackend`.

.. toctree::
  :includehidden:
  :glob:
  :maxdepth: 1

  _api/airflow/secrets/index