sunank200 commented on code in PR #51153: URL: https://github.com/apache/airflow/pull/51153#discussion_r2123382794
########## task-sdk/docs/index.rst: ########## @@ -0,0 +1,161 @@ + .. Licensed to the Apache Software Foundation (ASF) under one + or more contributor license agreements. See the NOTICE file + distributed with this work for additional information + regarding copyright ownership. The ASF licenses this file + to you under the Apache License, Version 2.0 (the + "License"); you may not use this file except in compliance + with the License. You may obtain a copy of the License at + + .. http://www.apache.org/licenses/LICENSE-2.0 + + .. Unless required by applicable law or agreed to in writing, + software distributed under the License is distributed on an + "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY + KIND, either express or implied. See the License for the + specific language governing permissions and limitations + under the License. + +Apache Airflow Task Execution SDK +================================= + +:any:`DAG` is where to start. :any:`dag` + +The Apache Airflow Task Execution SDK(Task SDK) provides Python-native interfaces for defining DAGs (via decorators), +executing tasks in isolated subprocesses and interacting with Airflow resources +(e.g., Connections, Variables, XComs, Metrics, Logs, and OpenLineage events) at runtime. +It also includes core execution-time components to manage communication between the worker +and the Airflow scheduler/backend. + +This approach minimises boilerplate and keeps your DAG definitions concise and readable. + + +Installation +------------ +To install the Task SDK, run: + +.. code-block:: bash + + pip install apache-airflow-task-sdk + +Getting Started +--------------- +Define a basic DAG and task in just a few lines of Python: + +.. literalinclude:: ../../airflow-core/src/airflow/example_dags/example_simplest_dag.py + :language: python + :start-after: [START simplest_dag] + :end-before: [END simplest_dag] + :caption: Simplest DAG with ``@dag`` and ``@task`` + +Key Concepts +------------ +Defining DAGs +~~~~~~~~~~~~~ +Use ``@dag`` to convert a function into an Airflow DAG. All nested ``@task`` calls +become part of the workflow. + +.. literalinclude:: ../../airflow-core/src/airflow/example_dags/example_dag_decorator.py + :language: python + :start-after: [START dag_decorator_usage] + :end-before: [END dag_decorator_usage] + :caption: Using the ``@dag`` decorator with custom tasks and operators. + +Decorators +~~~~~~~~~~ +Simplify DAG and task definitions using decorators: + +- ``@task``: define tasks. +- ``@task_group``: group related tasks into logical units. +- ``@setup`` and ``@teardown``: define setup and teardown tasks for DAGs and TaskGroups. + +.. literalinclude:: ../../airflow-core/src/airflow/example_dags/example_task_group_decorator.py + :language: python + :start-after: [START howto_task_group_decorator] + :end-before: [END howto_task_group_decorator] + :caption: Group tasks using the ``@task_group`` decorator. + +.. literalinclude:: ../../airflow-core/src/airflow/example_dags/example_setup_teardown_taskflow.py + :language: python + :caption: Define setup and teardown tasks with ``@setup`` and ``@teardown``. + +Tasks and Operators +~~~~~~~~~~~~~~~~~~~ +Wrap Python callables with ``@task`` to create tasks, leverage dynamic task mapping with +``.expand()``, and pass data via ``XComArg``. You can also create traditional Operators +(e.g., sensors) via classes imported from the SDK: + + - **BaseOperator**, **Sensor**, **OperatorLink**, **Notifier**, "XComArg", etc. + (see the **api reference** section for details) + +.. literalinclude:: ../../airflow-core/src/airflow/example_dags/example_dynamic_task_mapping.py + :language: python + :start-after: [START example_dynamic_task_mapping] + :end-before: [END example_dynamic_task_mapping] + :caption: Dynamic task mapping with ``expand()`` + +.. literalinclude:: ../../airflow-core/src/airflow/example_dags/example_xcomargs.py + :language: python + :caption: Using ``XComArg`` to chain tasks based on return values. + +Assets +~~~~~~ +Model data as assets and emit them to downstream tasks with the SDK's asset library under +``airflow.sdk.definitions.asset``. You can use: + + - ``@asset``, ``AssetAlias``, etc. (see the **api reference** section below) + +.. literalinclude:: ../../airflow-core/src/airflow/example_dags/example_assets.py + :language: python + :start-after: [START asset_def] + :end-before: [END asset_def] + :caption: Defining an ``Asset`` + +.. literalinclude:: ../../airflow-core/src/airflow/example_dags/example_asset_alias.py + :language: python + :caption: Defining asset aliases with ``AssetAlias``. + +Execution Time Components +~~~~~~~~~~~~~~~~~~~~~~~~~ +At runtime, tasks run in an isolated subprocess managed by the SDK: + + - **Supervisor** coordinates the worker's lifecycle. + - **TaskRunner** actually executes the user's task code. + - **Context** objects provide runtime metadata (e.g., connections, variables). + (see the **Execution Time** section below for details) + + +Everything Else +--------------- +In addition to "DAG" and "task"-level decorators, the Task SDK provides: + + * **Bases** (under ``airflow.sdk.bases``): + - ``BaseOperator`` + - ``Sensor`` + - ``OperatorLink`` + - ``Notifier`` + - ``XComArg`` + + * **Decorators**: + - ``@task``, ``@task_group``, ``@setup``, ``@teardown`` (exported at top level). + - These live in ``airflow.sdk.decorator`` but are re-exported in ``airflow.sdk``. 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