Ansible 中 register 注册变量

Ansible的register模块用于捕获和保存任务执行结果的，register是一个关键字，可以将任务执行的结果赋值给指定的变量名称，这个变量可以在后续任务中使用。

register模块可以捕获各种类型的输出，包括stdout、stderr、rc、changed等。也可以与其他模块一起使用，例如“when”条件、“loop”循环等。

在web1组的主机上执行任务，创建/tmp/dir1，并打印创建结果，代码示意如下：

[root@pubserver ansible]# vim regi1.yml

---
- name: create file /tmp/dir1
  hosts: web1
  tasks:
    - name: create file
      file:
        path: /tmp/dir1
        state: touch
      register: result

    - name: display output
      debug:
        msg: "{{result}}"

[root@pubserver ansible]# ansible-playbook regi1.yml 

        .............

TASK [display output] *****************************************************************************************************************************
ok: [web1] => {
    "msg": {
        "changed": true,
        "dest": "/tmp/dir1",
        "diff": {
            "after": {
                "atime": 1693385587.9442923,
                "mtime": 1693385587.9442923,
                "path": "/tmp/dir1",
                "state": "touch"
            },
            "before": {
                "atime": 1693385587.9377587,
                "mtime": 1693385587.9377587,
                "path": "/tmp/dir1",
                "state": "absent"
            }
        },
        "failed": false,
        "gid": 0,
        "group": "root",
        "mode": "0644",
        "owner": "root",
        "secontext": "unconfined_u:object_r:user_tmp_t:s0",
        "size": 0,
        "state": "file",
        "uid": 0
    }
}

PLAY RECAP ****************************************************************************************************************************************
web1                       : ok=3    changed=1    unreachable=0    failed=0    skipped=0    rescued=0    ignored=0

在webservers组的主机上执行任务，创建文件/tmp/ademo/abc，如果创建不成功，则通过debug输出create failed，代码示意如下：

[root@pubserver ansible]# vim regi2.yml
---
- name: create file /tmp/ademo/abc
  hosts: webservers
  ignore_errors: yes
  tasks:
    - name: create file
      file:
        path: /tmp/ademo/abc
        state: touch
      register: result

    - name: debug output if create failed
      debug:
        msg: "create failed"
      when: not result.changed

# 测试
[root@pubserver ansible]# ansible-playbook regi2.yml 

        ..........

TASK [create file] ********************************************************************************************************************************
fatal: [web2]: FAILED! => {"changed": false, "msg": "Error, could not touch target: [Errno 2] 没有那个文件或目录: b'/tmp/ademo/abc'", "path": "/tmp/ademo/abc"}
...ignoring
fatal: [web1]: FAILED! => {"changed": false, "msg": "Error, could not touch target: [Errno 2] 没有那个文件或目录: b'/tmp/ademo/abc'", "path": "/tmp/ademo/abc"}
...ignoring

TASK [debug output if create failed] **************************************************************************************************************
ok: [web1] => {
    "msg": "create failed"
}
ok: [web2] => {
    "msg": "create failed"
}

PLAY RECAP ****************************************************************************************************************************************
web1                       : ok=3    changed=0    unreachable=0    failed=0    skipped=0    rescued=0    ignored=1   
web2                       : ok=3    changed=0    unreachable=0    failed=0    skipped=0    rescued=0    ignored=1