问题现象

在使用plabook中的when做过滤脚本如下：

---
- hosts: realservers
  remote_user: root

  tasks:
    - name: Check if httpd service is running
      command: systemctl status httpd
      register: result
      ignore_errors: True

    - name: Handle failed service check
      debug:
        msg: "The service is not running."
      when: result | failed

    - name: Handle successful service check
      debug:
        msg: "The service is running."
      when: result | success

使用when: result | success这种过滤条件发现报错如下：

"msg": "The conditional check 'result|failed' failed. The error was: template error while templating string: no filter named 'failed'. String: {% if result|failed %} True {% else %} False {% endif %}\n\nThe error appears to be in '/root/when_judge.yml': line 11, column 7, but may\nbe elsewhere in the file depending on the exact syntax problem.\n\nThe offending line appears to be:\n\n\n    - name: Handle failed service check\n      ^ here\n"

解决方案

后经过google发现官方已经不使用此种表达方式做过滤， 将|更改为is即可。

 参考文章：devops - Ansible: Conditional Statement wierd Error - Stack Overflow

测试结果 

修改后测试如下：

启动被控端httpd服务后，主控端查看状态变更为success任务

停止被控端httpd服务后，主控端查看状态变更为failed任务