| .. 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. |
| |
| |
| |
| .. _howto/operator:BashOperator: |
| |
| BashOperator |
| ============ |
| |
| Use the :class:`~airflow.operators.bash.BashOperator` to execute |
| commands in a `Bash <https://www.gnu.org/software/bash/>`__ shell. |
| |
| .. exampleinclude:: /../../airflow/example_dags/example_bash_operator.py |
| :language: python |
| :start-after: [START howto_operator_bash] |
| :end-before: [END howto_operator_bash] |
| |
| Templating |
| ---------- |
| |
| You can use :ref:`Jinja templates <jinja-templating>` to parameterize the |
| ``bash_command`` argument. |
| |
| .. exampleinclude:: /../../airflow/example_dags/example_bash_operator.py |
| :language: python |
| :start-after: [START howto_operator_bash_template] |
| :end-before: [END howto_operator_bash_template] |
| |
| |
| .. warning:: |
| |
| Care should be taken with "user" input or when using Jinja templates in the |
| ``bash_command``, as this bash operator does not perform any escaping or |
| sanitization of the command. |
| |
| This applies mostly to using "dag_run" conf, as that can be submitted via |
| users in the Web UI. Most of the default template variables are not at |
| risk. |
| |
| For example, do **not** do this: |
| |
| .. code-block:: python |
| |
| bash_task = BashOperator( |
| task_id="bash_task", |
| bash_command='echo "Here is the message: \'{{ dag_run.conf["message"] if dag_run else "" }}\'"', |
| ) |
| |
| Instead, you should pass this via the ``env`` kwarg and use double-quotes |
| inside the bash_command, as below: |
| |
| .. code-block:: python |
| |
| bash_task = BashOperator( |
| task_id="bash_task", |
| bash_command='echo "here is the message: \'$message\'"', |
| env={'message': '{{ dag_run.conf["message"] if dag_run else "" }}'}, |
| ) |
| |
| Troubleshooting |
| --------------- |
| |
| Jinja template not found |
| """""""""""""""""""""""" |
| |
| Add a space after the script name when directly calling a Bash script with |
| the ``bash_command`` argument. This is because Airflow tries to apply a Jinja |
| template to it, which will fail. |
| |
| .. code-block:: python |
| |
| t2 = BashOperator( |
| task_id='bash_example', |
| |
| # This fails with 'Jinja template not found' error |
| # bash_command="/home/batcher/test.sh", |
| |
| # This works (has a space after) |
| bash_command="/home/batcher/test.sh ", |
| dag=dag) |
| |
| However, if you want to use templating in your bash script, do not add the space |
| and instead put your bash script in a location relative to the directory containing |
| the DAG file. So if your DAG file is in ``/usr/local/airflow/dags/test_dag.py``, you can |
| move your ``test.sh`` file to any location under ``/usr/local/airflow/dags/`` (Example: |
| ``/usr/local/airflow/dags/scripts/test.sh``) and pass the relative path to ``bash_command`` |
| as shown below: |
| |
| .. code-block:: python |
| |
| t2 = BashOperator( |
| task_id='bash_example', |
| # "scripts" folder is under "/usr/local/airflow/dags" |
| bash_command="scripts/test.sh", |
| dag=dag) |
| |
| Creating separate folder for bash scripts may be desirable for many reasons, like |
| separating your script's logic and pipeline code, allowing for proper code highlighting |
| in files composed in different languages, and general flexibility in structuring |
| pipelines. |
| |
| It is also possible to define your ``template_searchpath`` as pointing to any folder |
| locations in the DAG constructor call. |
| |
| Example: |
| |
| .. code-block:: python |
| |
| dag = DAG("example_bash_dag", template_searchpath="/opt/scripts") |
| t2 = BashOperator( |
| task_id='bash_example', |
| # "test.sh" is a file under "/opt/scripts" |
| bash_command="test.sh ", |
| dag=dag) |