#
# 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.
import os
import signal
from subprocess import PIPE, STDOUT, Popen
from tempfile import TemporaryDirectory, gettempdir
from typing import Dict, Optional
from airflow.exceptions import AirflowException
from airflow.models import BaseOperator
from airflow.utils.decorators import apply_defaults
from airflow.utils.operator_helpers import context_to_airflow_vars
[docs]class BashOperator(BaseOperator):
r"""
Execute a Bash script, command or set of commands.
.. seealso::
For more information on how to use this operator, take a look at the guide:
:ref:`howto/operator:BashOperator`
If BaseOperator.do_xcom_push is True, the last line written to stdout
will also be pushed to an XCom when the bash command completes
:param bash_command: The command, set of commands or reference to a
bash script (must be '.sh') to be executed. (templated)
:type bash_command: str
:param env: If env is not None, it must be a dict that defines the
environment variables for the new process; these are used instead
of inheriting the current process environment, which is the default
behavior. (templated)
:type env: dict
:param output_encoding: Output encoding of bash command
:type output_encoding: str
On execution of this operator the task will be up for retry
when exception is raised. However, if a sub-command exits with non-zero
value Airflow will not recognize it as failure unless the whole shell exits
with a failure. The easiest way of achieving this is to prefix the command
with ``set -e;``
Example:
.. code-block:: python
bash_command = "set -e; python3 script.py '{{ next_execution_date }}'"
.. note::
Add a space after the script name when directly calling a ``.sh`` script with the
``bash_command`` argument -- for example ``bash_command="my_script.sh "``. This
is because Airflow tries to apply load this file and process it as a Jinja template to
it ends with ``.sh``, which will likely not be what most users want.
.. 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 "" }}'},
)
"""
[docs] template_fields = ('bash_command', 'env')
[docs] template_fields_renderers = {'bash_command': 'bash', 'env': 'json'}
[docs] template_ext = (
'.sh',
'.bash',
)
@apply_defaults
def __init__(
self,
*,
bash_command: str,
env: Optional[Dict[str, str]] = None,
output_encoding: str = 'utf-8',
**kwargs,
) -> None:
super().__init__(**kwargs)
self.bash_command = bash_command
self.env = env
self.output_encoding = output_encoding
if kwargs.get('xcom_push') is not None:
raise AirflowException("'xcom_push' was deprecated, use 'BaseOperator.do_xcom_push' instead")
self.sub_process = None
[docs] def execute(self, context):
"""
Execute the bash command in a temporary directory
which will be cleaned afterwards
"""
self.log.info('Tmp dir root location: \n %s', gettempdir())
# Prepare env for child process.
env = self.env
if env is None:
env = os.environ.copy()
airflow_context_vars = context_to_airflow_vars(context, in_env_var_format=True)
self.log.debug(
'Exporting the following env vars:\n%s',
'\n'.join([f"{k}={v}" for k, v in airflow_context_vars.items()]),
)
env.update(airflow_context_vars)
with TemporaryDirectory(prefix='airflowtmp') as tmp_dir:
def pre_exec():
# Restore default signal disposition and invoke setsid
for sig in ('SIGPIPE', 'SIGXFZ', 'SIGXFSZ'):
if hasattr(signal, sig):
signal.signal(getattr(signal, sig), signal.SIG_DFL)
os.setsid()
self.log.info('Running command: %s', self.bash_command)
self.sub_process = Popen( # pylint: disable=subprocess-popen-preexec-fn
['bash', "-c", self.bash_command],
stdout=PIPE,
stderr=STDOUT,
cwd=tmp_dir,
env=env,
preexec_fn=pre_exec,
)
self.log.info('Output:')
line = ''
for raw_line in iter(self.sub_process.stdout.readline, b''):
line = raw_line.decode(self.output_encoding).rstrip()
self.log.info("%s", line)
self.sub_process.wait()
self.log.info('Command exited with return code %s', self.sub_process.returncode)
if self.sub_process.returncode != 0:
raise AirflowException('Bash command failed. The command returned a non-zero exit code.')
return line
[docs] def on_kill(self):
self.log.info('Sending SIGTERM signal to bash process group')
if self.sub_process and hasattr(self.sub_process, 'pid'):
os.killpg(os.getpgid(self.sub_process.pid), signal.SIGTERM)