php - 通过具有幂等性的 Ansible 安装 PHP Pear 包

Question

我目前正在使用 Ansible 为 PHP 安装 Pear 包，如下所示:

- name: Add Phergie PEAR channel.
  command: pear channel-discover pear.phergie.org
  ignore_errors: yes

- name: Install Phergie and related plugins.
  command: pear install pear.phergie.org/{{ item }}
  with_items:
  - Phergie
  - Phergie_Plugin_AltNick
  ignore_errors: yes

ignore_errors 是必需的，因为 pear 在运行之前已成功运行/完成的命令时总是报告错误(例如:

TASK: [Add Phergie PEAR channel.] ********************************************* 
failed: [10.31.9.210] => {"changed": true, "cmd": ["pear", "channel-discover", "pear.phergie.org"], "delta": "0:00:01.089340", "end": "2013-12-27 10:16:25.640083", "item": "", "rc": 1, "start": "2013-12-27 10:16:24.550743"}
stdout: Channel "pear.phergie.org" is already initialized
...ignoring

TASK: [Install Phergie and related plugins.] ********************************** 
failed: [10.31.9.210] => (item=Phergie) => {"changed": true, "cmd": ["pear", "install", "pear.phergie.org/Phergie"], "delta": "0:00:03.698780", "end": "2013-12-27 10:16:30.337371", "item": "Phergie", "rc": 1, "start": "2013-12-27 10:16:26.638591"}
stdout: phergie/Phergie is already installed and is the same as the released version 2.1.0
install failed
...ignoring
failed: [10.31.9.210] => (item=Phergie_Plugin_AltNick) => {"changed": true, "cmd": ["pear", "install", "pear.phergie.org/Phergie_Plugin_AltNick"], "delta": "0:00:01.779589", "end": "2013-12-27 10:16:33.231524", "item": "Phergie_Plugin_AltNick", "rc": 1, "start": "2013-12-27 10:16:31.451935"}
stdout: phergie/Phergie_Plugin_AltNick is already installed and is the same as the released version 2.1.0
install failed
...ignoring

有没有更好(更幂等)的方式来运行 pear 命令，而不必滚动浏览一堆大的、红色的被忽略的错误？

Answer 1

好的，所以在稍微尝试了一下 changed_when 属性之后，我终于找到了解决方案(在不同的剧本上进行测试，我安装的是 drush 而不是 Phergie，但问题/解决方案完全相同:

剧本:

- name: Setup drush PEAR channel.
  command: pear channel-discover pear.drush.org
  register: channel_result
  environment: proxy_env
  changed_when: "'initialized' not in channel_result.stdout"
  # TODO: This will always error out the first time it's run.
  failed_when: "'already initialized' not in channel_result.stdout"

- name: Install drush.
  command: pear install drush/drush
  register: drush_result
  environment: proxy_env
  changed_when: "'installed' not in drush_result.stdout"
  failed_when: "'6.2.0.0' not in drush_result.stdout"

Ansible 的新输出:

TASK: [Setup drush PEAR channel.] ********************************************* 
ok: [midwesternmac]

TASK: [Install drush.] ******************************************************** 
ok: [midwesternmac]

所以现在在摘要中，Ansible 不会报告每个服务器和每个 pear 命令的额外“更改”，而是仅报告“已更改”，前提是存在更改。有关 changed_when 和 failed_when(需要 Ansible >= 1.3)的更多文档(虽然稀少)可在此处获得:Error Handling In Playbooks