passing_params_via_test_command

Example DAG demonstrating the usage of the params arguments in templated arguments.

Airflow Fundamentals


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Last Updated: Feb. 18, 2022

Run this DAG

1. Install the Astronomer CLI:Skip if you already have the CLI

2. Initate the project in a local directory:

3. Copy and paste the code below into a file in the

dags
directory.

4. Run the DAG from the local directory where the project was initiated:

#
# 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.
"""Example DAG demonstrating the usage of the params arguments in templated arguments."""
from __future__ import annotations
import datetime
import os
from textwrap import dedent
import pendulum
from airflow import DAG
from airflow.decorators import task
from airflow.operators.bash import BashOperator
@task(task_id="run_this")
def my_py_command(params, test_mode=None, task=None):
"""
Print out the "foo" param passed in via
`airflow tasks test example_passing_params_via_test_command run_this <date>
-t '{"foo":"bar"}'`
"""
if test_mode:
print(
f" 'foo' was passed in via test={test_mode} command : kwargs[params][foo] = {task.params['foo']}"
)
# Print out the value of "miff", passed in below via the Python Operator
print(f" 'miff' was passed in via task params = {params['miff']}")
return 1
@task(task_id="env_var_test_task")
def print_env_vars(test_mode=None):
"""
Print out the "foo" param passed in via
`airflow tasks test example_passing_params_via_test_command env_var_test_task <date>
--env-vars '{"foo":"bar"}'`
"""
if test_mode:
print(f"foo={os.environ.get('foo')}")
print(f"AIRFLOW_TEST_MODE={os.environ.get('AIRFLOW_TEST_MODE')}")
with DAG(
"example_passing_params_via_test_command",
schedule='*/1 * * * *',
start_date=pendulum.datetime(2021, 1, 1, tz="UTC"),
catchup=False,
dagrun_timeout=datetime.timedelta(minutes=4),
tags=['example'],
) as dag:
run_this = my_py_command(params={"miff": "agg"})
my_command = dedent(
"""
echo "'foo' was passed in via Airflow CLI Test command with value '$FOO'"
echo "'miff' was passed in via BashOperator with value '$MIFF'"
"""
)
also_run_this = BashOperator(
task_id='also_run_this',
bash_command=my_command,
params={"miff": "agg"},
env={"FOO": "{{ params.foo }}", "MIFF": "{{ params.miff }}"},
)
env_var_test_task = print_env_vars()
run_this >> also_run_this