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57 changes: 57 additions & 0 deletions airflow/example_dags/example_custom_weight.py
Original file line number Diff line number Diff line change
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#
# 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 CustomWeightRule."""

from __future__ import annotations

import datetime

import pendulum
from airflow.example_dags.plugins.decreasing_priority_weight_strategy import DecreasingPriorityStrategy

# [START example_custom_weight_dag]
from airflow.models.dag import DAG
from airflow.providers.standard.operators.bash import BashOperator
from airflow.providers.standard.operators.empty import EmptyOperator

with DAG(
dag_id="example_custom_weight",
schedule="0 0 * * *",
start_date=pendulum.datetime(2021, 1, 1, tz="UTC"),
catchup=False,
dagrun_timeout=datetime.timedelta(minutes=60),
tags=["example", "example2"],
) as dag:
start = EmptyOperator(
task_id="start",
)

# provide the class instance
task_1 = BashOperator(task_id="task_1", bash_command="echo 1", weight_rule=DecreasingPriorityStrategy())

# or provide the path of the class
task_2 = BashOperator(
task_id="task_2",
bash_command="echo 1",
weight_rule="airflow.example_dags.plugins.decreasing_priority_weight_strategy.DecreasingPriorityStrategy",
)

task_non_custom = BashOperator(task_id="task_non_custom", bash_command="echo 1", priority_weight=2)

start >> [task_1, task_2, task_non_custom]
# [END example_custom_weight_dag]
Original file line number Diff line number Diff line change
Expand Up @@ -84,21 +84,18 @@ registering it in a plugin.
:end-before: [END custom_priority_weight_strategy]


Then to use it, you can create an instance of the custom class and provide it in the ``weight_rule`` parameter
of the task or provide the path of the custom class:
To check if the custom priority weight strategy is already available in Airflow, you can run the bash command
``airflow plugins``. Then to use it, you can create an instance of the custom class and provide it in the
``weight_rule`` parameter of the task or provide the path of the custom class:

.. code-block:: python

from custom_weight_rule_module import CustomPriorityWeightStrategy
.. exampleinclude:: /../../airflow/example_dags/example_custom_weight.py
:language: python
:dedent: 0
:start-after: [START example_custom_weight_dag]
:end-before: [END example_custom_weight_dag]

# provide the class instance
task1 = BashOperator(task_id="task", bash_command="echo 1", weight_rule=CustomPriorityWeightStrategy())

# or provide the path of the class
task1 = BashOperator(
task_id="task",
bash_command="echo 1",
weight_rule="custom_weight_rule_module.CustomPriorityWeightStrategy",
)
After the DAG is running, you can check the ``priority_weight`` parameter on the task to verify that it is using
the custom priority strategy rule.

|experimental|