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.

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.

BaseSensorOperator

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

Operators packages

All operators are in the following packages:

• airflow.operators
• airflow.sensors
• airflow.contrib.operators
• airflow.contrib.sensors

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 BaseHook.

Hooks packages

All hooks are in the following packages:

• airflow.hooks
• airflow.contrib.hooks

Executors

Executors are the mechanism by which task instances get run. All executors are derived from BaseExecutor.

Executors packages

All executors are in the following packages:

• airflow.executors
• airflow.contrib.executors

Models

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

• airflow.models

Core and community package

Formerly the core code was maintained by the original creators - Airbnb. The code that was in the contrib package was supported by the community. The project was passed to the Apache community and currently the entire code is maintained by the community, so now the division has no justification, and it is only due to historical reasons. Currently, all new classes are added only to the contrib package.