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import inspect
import os
import pickle
import shutil
import sys
import types
import warnings
from tempfile import TemporaryDirectory
from textwrap import dedent
from typing import Callable, Dict, Iterable, List, Optional, Union
import dill
from airflow.exceptions import AirflowException
from airflow.models import BaseOperator
from airflow.models.skipmixin import SkipMixin
from airflow.models.taskinstance import _CURRENT_CONTEXT
from airflow.utils.context import Context
from airflow.utils.operator_helpers import determine_kwargs
from airflow.utils.process_utils import execute_in_subprocess
from airflow.utils.python_virtualenv import prepare_virtualenv, write_python_script
[docs]def task(python_callable: Optional[Callable] = None, multiple_outputs: Optional[bool] = None, **kwargs):
"""
Deprecated function that calls @task.python and allows users to turn a python function into
an Airflow task. Please use the following instead:
from airflow.decorators import task
@task
def my_task()
:param python_callable: A reference to an object that is callable
:type python_callable: python callable
:param op_kwargs: a dictionary of keyword arguments that will get unpacked
in your function (templated)
:type op_kwargs: dict
:param op_args: a list of positional arguments that will get unpacked when
calling your callable (templated)
:type op_args: list
:param multiple_outputs: if set, function return value will be
unrolled to multiple XCom values. Dict will unroll to xcom values with keys as keys.
Defaults to False.
:type multiple_outputs: bool
:return:
"""
# To maintain backwards compatibility, we import the task object into this file
# This prevents breakages in dags that use `from airflow.operators.python import task`
from airflow.decorators.python import python_task
warnings.warn(
"""airflow.operators.python.task is deprecated. Please use the following instead
from airflow.decorators import task
@task
def my_task()""",
DeprecationWarning,
stacklevel=2,
)
return python_task(python_callable=python_callable, multiple_outputs=multiple_outputs, **kwargs)
[docs]class PythonOperator(BaseOperator):
"""
Executes a Python callable
.. seealso::
For more information on how to use this operator, take a look at the guide:
:ref:`howto/operator:PythonOperator`
When running your callable, Airflow will pass a set of keyword arguments that can be used in your
function. This set of kwargs correspond exactly to what you can use in your jinja templates.
For this to work, you need to define ``**kwargs`` in your function header, or you can add directly the
keyword arguments you would like to get - for example with the below code your callable will get
the values of ``ti`` and ``next_ds`` context variables.
With explicit arguments:
.. code-block:: python
def my_python_callable(ti, next_ds):
pass
With kwargs:
.. code-block:: python
def my_python_callable(**kwargs):
ti = kwargs["ti"]
next_ds = kwargs["next_ds"]
:param python_callable: A reference to an object that is callable
:type python_callable: python callable
:param op_kwargs: a dictionary of keyword arguments that will get unpacked
in your function
:type op_kwargs: dict (templated)
:param op_args: a list of positional arguments that will get unpacked when
calling your callable
:type op_args: list (templated)
:param templates_dict: a dictionary where the values are templates that
will get templated by the Airflow engine sometime between
``__init__`` and ``execute`` takes place and are made available
in your callable's context after the template has been applied. (templated)
:type templates_dict: dict[str]
:param templates_exts: a list of file extensions to resolve while
processing templated fields, for examples ``['.sql', '.hql']``
:type templates_exts: list[str]
"""
[docs] template_fields = ('templates_dict', 'op_args', 'op_kwargs')
[docs] template_fields_renderers = {"templates_dict": "json", "op_args": "py", "op_kwargs": "py"}
# since we won't mutate the arguments, we should just do the shallow copy
# there are some cases we can't deepcopy the objects(e.g protobuf).
[docs] shallow_copy_attrs = (
'python_callable',
'op_kwargs',
)
def __init__(
self,
*,
python_callable: Callable,
op_args: Optional[List] = None,
op_kwargs: Optional[Dict] = None,
templates_dict: Optional[Dict] = None,
templates_exts: Optional[List[str]] = None,
**kwargs,
) -> None:
if kwargs.get("provide_context"):
warnings.warn(
"provide_context is deprecated as of 2.0 and is no longer required",
DeprecationWarning,
stacklevel=2,
)
kwargs.pop('provide_context', None)
super().__init__(**kwargs)
if not callable(python_callable):
raise AirflowException('`python_callable` param must be callable')
self.python_callable = python_callable
self.op_args = op_args or []
self.op_kwargs = op_kwargs or {}
self.templates_dict = templates_dict
if templates_exts:
self.template_ext = templates_exts
[docs] def execute(self, context: Dict):
context.update(self.op_kwargs)
context['templates_dict'] = self.templates_dict
self.op_kwargs = determine_kwargs(self.python_callable, self.op_args, context)
return_value = self.execute_callable()
self.log.info("Done. Returned value was: %s", return_value)
return return_value
[docs] def execute_callable(self):
"""
Calls the python callable with the given arguments.
:return: the return value of the call.
:rtype: any
"""
return self.python_callable(*self.op_args, **self.op_kwargs)
[docs]class BranchPythonOperator(PythonOperator, SkipMixin):
"""
Allows a workflow to "branch" or follow a path following the execution
of this task.
It derives the PythonOperator and expects a Python function that returns
a single task_id or list of task_ids to follow. The task_id(s) returned
should point to a task directly downstream from {self}. All other "branches"
or directly downstream tasks are marked with a state of ``skipped`` so that
these paths can't move forward. The ``skipped`` states are propagated
downstream to allow for the DAG state to fill up and the DAG run's state
to be inferred.
"""
[docs] def execute(self, context: Dict):
branch = super().execute(context)
# TODO: The logic should be moved to SkipMixin to be available to all branch operators.
if isinstance(branch, str):
branches = {branch}
elif isinstance(branch, list):
branches = set(branch)
else:
raise AirflowException("Branch callable must return either a task ID or a list of IDs")
valid_task_ids = set(context["dag"].task_ids)
invalid_task_ids = branches - valid_task_ids
if invalid_task_ids:
raise AirflowException(
f"Branch callable must return valid task_ids. Invalid tasks found: {invalid_task_ids}"
)
self.skip_all_except(context['ti'], branch)
return branch
[docs]class ShortCircuitOperator(PythonOperator, SkipMixin):
"""
Allows a workflow to continue only if a condition is met. Otherwise, the
workflow "short-circuits" and downstream tasks are skipped.
The ShortCircuitOperator is derived from the PythonOperator. It evaluates a
condition and short-circuits the workflow if the condition is False. Any
downstream tasks are marked with a state of "skipped". If the condition is
True, downstream tasks proceed as normal.
The condition is determined by the result of `python_callable`.
"""
[docs] def execute(self, context: Dict):
condition = super().execute(context)
self.log.info("Condition result is %s", condition)
if condition:
self.log.info('Proceeding with downstream tasks...')
return
self.log.info('Skipping downstream tasks...')
downstream_tasks = context['task'].get_flat_relatives(upstream=False)
self.log.debug("Downstream task_ids %s", downstream_tasks)
if downstream_tasks:
self.skip(context['dag_run'], context['ti'].execution_date, downstream_tasks)
self.log.info("Done.")
[docs]class PythonVirtualenvOperator(PythonOperator):
"""
Allows one to run a function in a virtualenv that is created and destroyed
automatically (with certain caveats).
The function must be defined using def, and not be
part of a class. All imports must happen inside the function
and no variables outside of the scope may be referenced. A global scope
variable named virtualenv_string_args will be available (populated by
string_args). In addition, one can pass stuff through op_args and op_kwargs, and one
can use a return value.
Note that if your virtualenv runs in a different Python major version than Airflow,
you cannot use return values, op_args, op_kwargs, or use any macros that are being provided to
Airflow through plugins. You can use string_args though.
.. seealso::
For more information on how to use this operator, take a look at the guide:
:ref:`howto/operator:PythonVirtualenvOperator`
:param python_callable: A python function with no references to outside variables,
defined with def, which will be run in a virtualenv
:type python_callable: function
:param requirements: A list of requirements as specified in a pip install command
:type requirements: list[str]
:param python_version: The Python version to run the virtualenv with. Note that
both 2 and 2.7 are acceptable forms.
:type python_version: Optional[Union[str, int, float]]
:param use_dill: Whether to use dill to serialize
the args and result (pickle is default). This allow more complex types
but requires you to include dill in your requirements.
:type use_dill: bool
:param system_site_packages: Whether to include
system_site_packages in your virtualenv.
See virtualenv documentation for more information.
:type system_site_packages: bool
:param op_args: A list of positional arguments to pass to python_callable.
:type op_args: list
:param op_kwargs: A dict of keyword arguments to pass to python_callable.
:type op_kwargs: dict
:param string_args: Strings that are present in the global var virtualenv_string_args,
available to python_callable at runtime as a list[str]. Note that args are split
by newline.
:type string_args: list[str]
:param templates_dict: a dictionary where the values are templates that
will get templated by the Airflow engine sometime between
``__init__`` and ``execute`` takes place and are made available
in your callable's context after the template has been applied
:type templates_dict: dict of str
:param templates_exts: a list of file extensions to resolve while
processing templated fields, for examples ``['.sql', '.hql']``
:type templates_exts: list[str]
"""
[docs] BASE_SERIALIZABLE_CONTEXT_KEYS = {
'ds',
'ds_nodash',
'inlets',
'next_ds',
'next_ds_nodash',
'outlets',
'prev_ds',
'prev_ds_nodash',
'run_id',
'task_instance_key_str',
'test_mode',
'tomorrow_ds',
'tomorrow_ds_nodash',
'ts',
'ts_nodash',
'ts_nodash_with_tz',
'yesterday_ds',
'yesterday_ds_nodash',
}
[docs] PENDULUM_SERIALIZABLE_CONTEXT_KEYS = {
'data_interval_end',
'data_interval_start',
'execution_date',
'logical_date',
'next_execution_date',
'prev_data_interval_end_success',
'prev_data_interval_start_success',
'prev_execution_date',
'prev_execution_date_success',
'prev_start_date_success',
}
[docs] AIRFLOW_SERIALIZABLE_CONTEXT_KEYS = {'macros', 'conf', 'dag', 'dag_run', 'task', 'params'}
def __init__(
self,
*,
python_callable: Callable,
requirements: Optional[Iterable[str]] = None,
python_version: Optional[Union[str, int, float]] = None,
use_dill: bool = False,
system_site_packages: bool = True,
op_args: Optional[List] = None,
op_kwargs: Optional[Dict] = None,
string_args: Optional[Iterable[str]] = None,
templates_dict: Optional[Dict] = None,
templates_exts: Optional[List[str]] = None,
**kwargs,
):
if (
not isinstance(python_callable, types.FunctionType)
or isinstance(python_callable, types.LambdaType)
and python_callable.__name__ == "<lambda>"
):
raise AirflowException('PythonVirtualenvOperator only supports functions for python_callable arg')
if (
python_version
and str(python_version)[0] != str(sys.version_info.major)
and (op_args or op_kwargs)
):
raise AirflowException(
"Passing op_args or op_kwargs is not supported across different Python "
"major versions for PythonVirtualenvOperator. Please use string_args."
)
if not shutil.which("virtualenv"):
raise AirflowException('PythonVirtualenvOperator requires virtualenv, please install it.')
super().__init__(
python_callable=python_callable,
op_args=op_args,
op_kwargs=op_kwargs,
templates_dict=templates_dict,
templates_exts=templates_exts,
**kwargs,
)
self.requirements = list(requirements or [])
self.string_args = string_args or []
self.python_version = python_version
self.use_dill = use_dill
self.system_site_packages = system_site_packages
if not self.system_site_packages:
if self.use_dill and 'dill' not in self.requirements:
self.requirements.append('dill')
self.pickling_library = dill if self.use_dill else pickle
[docs] def execute(self, context: Context):
serializable_keys = set(self._iter_serializable_context_keys())
serializable_context = context.copy_only(serializable_keys)
return super().execute(context=serializable_context)
[docs] def execute_callable(self):
with TemporaryDirectory(prefix='venv') as tmp_dir:
if self.templates_dict:
self.op_kwargs['templates_dict'] = self.templates_dict
input_filename = os.path.join(tmp_dir, 'script.in')
output_filename = os.path.join(tmp_dir, 'script.out')
string_args_filename = os.path.join(tmp_dir, 'string_args.txt')
script_filename = os.path.join(tmp_dir, 'script.py')
prepare_virtualenv(
venv_directory=tmp_dir,
python_bin=f'python{self.python_version}' if self.python_version else None,
system_site_packages=self.system_site_packages,
requirements=self.requirements,
)
self._write_args(input_filename)
self._write_string_args(string_args_filename)
write_python_script(
jinja_context=dict(
op_args=self.op_args,
op_kwargs=self.op_kwargs,
pickling_library=self.pickling_library.__name__,
python_callable=self.python_callable.__name__,
python_callable_source=self.get_python_source(),
),
filename=script_filename,
render_template_as_native_obj=self.dag.render_template_as_native_obj,
)
execute_in_subprocess(
cmd=[
f'{tmp_dir}/bin/python',
script_filename,
input_filename,
output_filename,
string_args_filename,
]
)
return self._read_result(output_filename)
[docs] def get_python_source(self):
"""
Returns the source of self.python_callable
@return:
"""
return dedent(inspect.getsource(self.python_callable))
def _write_args(self, filename):
if self.op_args or self.op_kwargs:
with open(filename, 'wb') as file:
self.pickling_library.dump({'args': self.op_args, 'kwargs': self.op_kwargs}, file)
def _iter_serializable_context_keys(self):
yield from self.BASE_SERIALIZABLE_CONTEXT_KEYS
if self.system_site_packages or 'apache-airflow' in self.requirements:
yield from self.AIRFLOW_SERIALIZABLE_CONTEXT_KEYS
yield from self.PENDULUM_SERIALIZABLE_CONTEXT_KEYS
elif 'pendulum' in self.requirements:
yield from self.PENDULUM_SERIALIZABLE_CONTEXT_KEYS
def _write_string_args(self, filename):
with open(filename, 'w') as file:
file.write('\n'.join(map(str, self.string_args)))
def _read_result(self, filename):
if os.stat(filename).st_size == 0:
return None
with open(filename, 'rb') as file:
try:
return self.pickling_library.load(file)
except ValueError:
self.log.error(
"Error deserializing result. Note that result deserialization "
"is not supported across major Python versions."
)
raise
[docs] def __deepcopy__(self, memo):
# module objects can't be copied _at all__
memo[id(self.pickling_library)] = self.pickling_library
return super().__deepcopy__(memo)
[docs]def get_current_context() -> Context:
"""
Obtain the execution context for the currently executing operator without
altering user method's signature.
This is the simplest method of retrieving the execution context dictionary.
**Old style:**
.. code:: python
def my_task(**context):
ti = context["ti"]
**New style:**
.. code:: python
from airflow.operators.python import get_current_context
def my_task():
context = get_current_context()
ti = context["ti"]
Current context will only have value if this method was called after an operator
was starting to execute.
"""
if not _CURRENT_CONTEXT:
raise AirflowException(
"Current context was requested but no context was found! "
"Are you running within an airflow task?"
)
return _CURRENT_CONTEXT[-1]