python - Airflow 使用 PythonOperator 的模板文件

Question

让 BashOperator 或 SqlOperator 为其模板选取外部文件的方法在某种程度上已清楚地记录在案，但查看 PythonOperator我对我从文档中理解的内容进行的测试不起作用。我不确定 templates_exts 和 templates_dict 参数如何正确交互以获取文件。

在我创建的 dags 文件夹中:pyoptemplate.sql 和 pyoptemplate.t 以及 test_python_operator_template.py:

pyoptemplate.sql:

SELECT * FROM {{params.table}};

pyoptemplate.t:

SELECT * FROM {{params.table}};

test_python_operator_template.py:

# coding: utf-8
# vim:ai:si:et:sw=4 ts=4 tw=80
"""
# A Test of Templates in PythonOperator
"""

from airflow import DAG
from airflow.operators.python_operator import PythonOperator
from datetime import datetime

import pprint

pp = pprint.PrettyPrinter(indent=4)


def templated_function(ds, **kwargs):
    """This function will try to use templates loaded from external files"""
    pp.pprint(ds)
    pp.pprint(kwargs)


# Define the DAG
dag = DAG(dag_id='test_python_operator_template_dag',
          default_args={"owner": "lamblin",
                        "start_date": datetime.now()},
          template_searchpath=['/Users/daniellamblin/airflow/dags'],
          schedule_interval='@once')


# Define the single task in this controller example DAG
op = PythonOperator(task_id='test_python_operator_template',
                    provide_context=True,
                    python_callable=templated_function,
                    templates_dict={
                        'pyoptemplate': '',
                        'pyoptemplate.sql': '',
                        'sql': 'pyoptemplate',
                        'file1':'pyoptemplate.sql',
                        'file2':'pyoptemplate.t',
                        'table': '{{params.table}}'},
                    templates_exts=['.sql','.t'],
                    params={'condition_param': True,
                            'message': 'Hello World',
                            'table': 'TEMP_TABLE'},
                    dag=dag)

运行结果显示 table 被正确地模板化为字符串，但其他人没有提取任何文件进行模板化。

dlamblin$ airflow test test_python_operator_template_dag test_python_operator_template 2017-01-18
[2017-01-18 23:58:06,698] {__init__.py:36} INFO - Using executor SequentialExecutor
[2017-01-18 23:58:07,342] {models.py:154} INFO - Filling up the DagBag from /Users/daniellamblin/airflow/dags
[2017-01-18 23:58:07,620] {models.py:1196} INFO - 
--------------------------------------------------------------------------------
Starting attempt 1 of 1
--------------------------------------------------------------------------------

[2017-01-18 23:58:07,620] {models.py:1219} INFO - Executing <Task(PythonOperator): test_python_operator_template> on 2017-01-18 00:00:00
'2017-01-18'
{   u'END_DATE': '2017-01-18',
    u'conf': <module 'airflow.configuration' from '/Library/Python/2.7/site-packages/airflow/configuration.pyc'>,
    u'dag': <DAG: test_python_operator_template_dag>,
    u'dag_run': None,
    u'ds_nodash': u'20170118',
    u'end_date': '2017-01-18',
    u'execution_date': datetime.datetime(2017, 1, 18, 0, 0),
    u'latest_date': '2017-01-18',
    u'macros': <module 'airflow.macros' from '/Library/Python/2.7/site-packages/airflow/macros/__init__.pyc'>,
    u'params': {   'condition_param': True,
                   'message': 'Hello World',
                   'table': 'TEMP_TABLE'},
    u'run_id': None,
    u'tables': None,
    u'task': <Task(PythonOperator): test_python_operator_template>,
    u'task_instance': <TaskInstance: test_python_operator_template_dag.test_python_operator_template 2017-01-18 00:00:00 [running]>,
    u'task_instance_key_str': u'test_python_operator_template_dag__test_python_operator_template__20170118',
    'templates_dict': {   'file1': u'pyoptemplate.sql',
                          'file2': u'pyoptemplate.t',
                          'pyoptemplate': u'',
                          'pyoptemplate.sql': u'',
                          'sql': u'pyoptemplate',
                          'table': u'TEMP_TABLE'},
    u'test_mode': True,
    u'ti': <TaskInstance: test_python_operator_template_dag.test_python_operator_template 2017-01-18 00:00:00 [running]>,
    u'tomorrow_ds': '2017-01-19',
    u'tomorrow_ds_nodash': u'20170119',
    u'ts': '2017-01-18T00:00:00',
    u'ts_nodash': u'20170118T000000',
    u'yesterday_ds': '2017-01-17',
    u'yesterday_ds_nodash': u'20170117'}
[2017-01-18 23:58:07,634] {python_operator.py:67} INFO - Done. Returned value was: None

Answer 1

从 Airflow 1.8 开始，PythonOperator 替换 __init__ 中的 template_ext 字段的方式不起作用。任务仅检查 __class__ 上的 template_ext。要创建一个获取 SQL 模板文件的 PythonOperator，您只需执行以下操作:

class SQLTemplatedPythonOperator(PythonOperator):
    template_ext = ('.sql',)

然后在任务运行时从任务中访问 SQL:

SQLTemplatedPythonOperator(
    templates_dict={'query': 'my_template.sql'},
    params={'my_var': 'my_value'},
    python_callable=my_func,
    provide_context=True,
)

def my_func(**context):
    context['templates_dict']['query']