Ansible 的 when 条件结合 run_once 会不小心跳过一些不应该跳过的任务 [英] Ansible's when condition combined with run_once will accidentally skip some tasks that should not be skipped

问题描述

我的inventory_hosts如下:

My inventory_hosts is as follows:

# inventory
[kafka]
192.168.1.1 
192.168.1.2 

[mysql]
192.168.1.3

我的 ansible-playbook 如下:

My ansible-playbook as follows:

site.yml:

- name: test
  hosts: all
  roles:
   - kafka

kafka 角色任务:

kafka roles tasks:

# main.yml
- name: get kafka groups length
  shell: echo "{{ groups['kafka']|length }}"
  run_once: true
  delegate_to: localhost
  when: "'kafka' in group_names"

预期结果

获取kafka组长度可以分别执行并委托给本地执行一次

get kafka groups length can be executed and delegated to local execution respectively and only once

实际结果

TASK [Gathering Facts] ******************************************************************************************************************************************************
ok: [192.168.1.1]
ok: [192.168.1.2]
ok: [192.168.1.3]

TASK [kafka : get mongodb groups length] ************************************************************************************************************************************
skipping: [192.168.1.3]

很奇怪的设计，我觉得不应该跳过，但他确实跳过了，我该怎么办?我期待同样的结果

Very strange design, I think it should not be skipped, but he did skip it, what should I do? I expect the same result

推荐答案

来自 Ansible 文档:

From the Ansible documentation:

group_names 是当前主机所在的所有组的列表(数组)

group_names is a list (array) of all the groups the current host is in

你的任务只运行一次，所以它只在第一台主机上运行，​​并且该主机只属于 kafka 组.这意味着您在该运行中的 group_names 变量仅包含 kafka.

You are only running your task once, so it only runs on the first host, and that host only belongs to the kafka group. This means that your group_names variable on that run only includes kafka.

试试这个:

- name: get kafka groups length
  shell: echo "{{ groups['kafka']|length }}"
  run_once: true
  delegate_to: localhost
  when: groups['kafka'] is defined

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