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用于确认进程是否正在运行的 Ansible 任务

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用于确认进程是否正在运行的 Ansible 任务

Ansible 2.1

在剧本中，我启动了一个流程：

- name: Start Automation Agent, and enable start on boot
  service: name=mongodb-mms-automation-agent state=started enabled=yes

从比赛回顾来看，该过程似乎已成功启动。

TASK [install : Start automation agent, and enable start on boot] **************
changed: [server1]

但是，当登录到远程主机并执行 时ps，进程没有运行。检查进程日志发现某些先决条件失败（预期）。

如何在剧本中编写任务来确认该过程已成功启动？

答案1

运行命令后，您可以使用failedJinja2 过滤器检查进程是否正在运行。

下面是一个使用命令输出systemctl status apache2来判断 Apache 是否正在运行的示例：

- name: Check if Apache is running
  command: systemctl status apache2
  ignore_errors: yes
  changed_when: false
  register: service_apache_status

- name: Report status of Apache
  fail:
    msg: |
      Service apache2 is not running.
      Output of `systemctl status apache2`:
      {{ service_apache_status.stdout }}
      {{ service_apache_status.stderr }}
  when: service_apache_status | failed

如果第一个任务的命令失败，则第二个任务将失败并显示第一个任务失败的原因。
返回代码存储在 中service_apache_status.rc。

失败的输出示例：

TASK: [Check if Apache is running] *********************** 
failed: [localhost] => {"changed": false, "cmd": ["systemctl", "status", "apache2"], "delta": "0:00:00.009379", "end": "2016-06-06 15:17:27.827172", "rc": 3, "start": "2016-06-06 15:17:27.817793", "stdout_lines": ["* apache2.service", "   Loaded: not-found (Reason: No such file or directory)", "   Active: inactive (dead)"], "warnings": []}
stdout: * apache2.service
   Loaded: not-found (Reason: No such file or directory)
   Active: inactive (dead)
...ignoring

TASK: [Report status of Apache] ***************************
failed: [localhost] => {"failed": true}
msg: apache2 is not running
systemctl status apache2 output:
* apache2.service
   Loaded: not-found (Reason: No such file or directory)
   Active: inactive (dead)

这里有一个不同的（尽管可能不太可靠）方法来pgrep检查进程是否正在运行：

- name: Check if Apache is running
  shell: pgrep apache2
  ignore_errors: yes
  changed_when: false
  register: service_apache_status

- name: Report status of Apache
  fail:
    msg: |
      Service apache2 is not running.
      Return code from `pgrep`:
      {{ service_apache_status.rc }}
  when: service_apache_status.rc != 0

答案2

这就是我现在做的事情：

- name: Confirm Automation Agent is running
  command: service mongodb-mms-automation-agent status
  register: agent_status
  failed_when: "'NOT' in agent_status.stdout"
  changed_when: False

failed_when在1.4中引入。changed_when: False用于抑制变化状态。阅读更多。

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