如何在Airflow中创建条件任务 [英] How to create a conditional task in Airflow

问题描述

我想在Airflow中创建一个条件任务，如下图所示。预期的情况如下：

I would like to create a conditional task in Airflow as described in the schema below. The expected scenario is the following:

• 任务1执行


• 如果任务1成功，则执行任务2a


• 其他如果任务1失败，则执行任务2b


• 最后执行任务3

• Task 1 executes
• If Task 1 succeed, then execute Task 2a
• Else If Task 1 fails, then execute Task 2b
• Finally execute Task 3

上面所有任务都是SSHExecuteOperator。
我想我应该使用ShortCircuitOperator和/或XCom来管理条件，但是我不清楚如何实现。

All tasks above are SSHExecuteOperator. I'm guessing I should be using the ShortCircuitOperator and / or XCom to manage the condition but I am not clear on how to implement that. Could you please describe the solution?

推荐答案

您必须使用气流触发规则

所有运算符都有一个trigger_rule参数，用于定义规则触发生成的任务。

All operators have a trigger_rule argument which defines the rule by which the generated task get triggered.

触发规则的可能性：

ALL_SUCCESS = 'all_success'
ALL_FAILED = 'all_failed'
ALL_DONE = 'all_done'
ONE_SUCCESS = 'one_success'
ONE_FAILED = 'one_failed'
DUMMY = 'dummy'

这是解决您的问题的想法：

Here is the idea to solve your problem:

from airflow.operators.ssh_execute_operator import SSHExecuteOperator
from airflow.utils.trigger_rule import TriggerRule
from airflow.contrib.hooks import SSHHook

sshHook = SSHHook(conn_id=<YOUR CONNECTION ID FROM THE UI>)

task_1 = SSHExecuteOperator(
        task_id='task_1',
        bash_command=<YOUR COMMAND>,
        ssh_hook=sshHook,
        dag=dag)

task_2 = SSHExecuteOperator(
        task_id='conditional_task',
        bash_command=<YOUR COMMAND>,
        ssh_hook=sshHook,
        dag=dag)

task_2a = SSHExecuteOperator(
        task_id='task_2a',
        bash_command=<YOUR COMMAND>,
        trigger_rule=TriggerRule.ALL_SUCCESS,
        ssh_hook=sshHook,
        dag=dag)

task_2b = SSHExecuteOperator(
        task_id='task_2b',
        bash_command=<YOUR COMMAND>,
        trigger_rule=TriggerRule.ALL_FAILED,
        ssh_hook=sshHook,
        dag=dag)

task_3 = SSHExecuteOperator(
        task_id='task_3',
        bash_command=<YOUR COMMAND>,
        trigger_rule=TriggerRule.ONE_SUCCESS,
        ssh_hook=sshHook,
        dag=dag)


task_2.set_upstream(task_1)
task_2a.set_upstream(task_2)
task_2b.set_upstream(task_2)
task_3.set_upstream(task_2a)
task_3.set_upstream(task_2b)

这篇关于如何在Airflow中创建条件任务的文章就介绍到这了，希望我们推荐的答案对大家有所帮助，也希望大家多多支持IT屋！