ansible系列(28)--ansible的playbook异常处理

1. playbook的异常处理
- 1.1 Playbook错误忽略
- 1.2 task执行失败强制调用handlers
1.3 控制Tasks报告状态为OK
- 1.4 changed_when检查任务结果

1. playbook的异常处理

1.1 Playbook错误忽略

在 playbook 执行的过程中，难免会遇到一些错误（返回结果不为0）。由于 playbook 遇到错误后，不会执行之后的任务，不便于调试，此时，可以使用 ignore_errors 来暂时忽略错误，使得 playbook 继续执行。

首先编写一个playbook文件：

[root@xuzhichao playbook]# cat ignore.yml
- hosts: localhost
  tasks:
    - name: Igonre False
      shell: /bin/false    <==此命令返回值一定不为0

    - name: Print Message
      debug:
        msg: "It's hard to here"

此时运行playbook时会在Igonre False任务中报错，无法继续向下运行：

[root@xuzhichao playbook]# ansible-playbook ignore.yml 

PLAY [localhost] **********************************************************************************************************************************************

TASK [Igonre False] *******************************************************************************************************************************************
fatal: [localhost]: FAILED! => {"changed": true, "cmd": "/bin/false", "delta": "0:00:00.024018", "end": "2021-08-05 21:36:36.638534", "msg": "non-zero return code", "rc": 1, "start": "2021-08-05 21:36:36.614516", "stderr": "", "stderr_lines": [], "stdout": "", "stdout_lines": []}

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

修改playbook文件，忽略中间task的错误，继续向下执行：

[root@xuzhichao playbook]# cat ignore.yml
- hosts: localhost
  tasks:
    - name: Igonre False
      shell: /bin/false
      ignore_errors: yes

    - name: Print Message
      debug:
        msg: "It's hard to here"

此时运行playbook会忽略掉中间task的错误，继续向下运行：

[root@xuzhichao playbook]# ansible-playbook ignore.yml 

PLAY [localhost] **********************************************************************************************************************************************

TASK [Igonre False] *******************************************************************************************************************************************
fatal: [localhost]: FAILED! => {"changed": true, "cmd": "/bin/false", "delta": "0:00:00.004268", "end": "2021-08-05 21:37:16.630140", "msg": "non-zero return code", "rc": 1, "start": "2021-08-05 21:37:16.625872", "stderr": "", "stderr_lines": [], "stdout": "", "stdout_lines": []}
...ignoring      <==忽略错误

TASK [Print Message] ******************************************************************************************************************************************
ok: [localhost] => {
    "msg": "It's hard to here"
}

PLAY RECAP ****************************************************************************************************************************************************
localhost                  : ok=2    changed=1    unreachable=0    failed=0    skipped=0    rescued=0    ignored=1

也可以写成下面的形式来保证task的返回值为0：

- hosts: localhost
  tasks:
    - name: Igonre False
      shell: /bin/false || /bin/ture

    - name: Print Message
      debug:
        msg: "It's hard to here"

1.2 task执行失败强制调用handlers

通常情况下，当 task 失败后， playbook 将会终止，任何在前面已经被 tasks notify 的 handlers 都不会被执行。如果你在 playbook 中设置了 force_handlers: yes 参数，被通知的 handlers 就会被强制执行。

请看下面的playbook：

[root@xuzhichao playbook]# cat force_handlers.yml
- hosts: localhost

  tasks:
    - name: Copy Configure File
      template:
        src: conf/nginx.conf.j2
        dest: /tmp/nginx.conf
      notify: Start Nginx

    - name: Igonre False
      shell: /bin/false

  handlers:
    - name: Start Nginx
      service:
        name: nginx
        state: started

当conf/nginx.conf.j2文件发生改变时，由于在 Igonre False这个task中执行出现错误，将不会执行handlers中的内容。

[root@xuzhichao playbook]# ansible-playbook force_handlers.yml 

PLAY [localhost] **********************************************************************************************************************************************

TASK [Copy Configure File] ************************************************************************************************************************************
ok: [localhost]

TASK [Igonre False] *******************************************************************************************************************************************
fatal: [localhost]: FAILED! => {"changed": true, "cmd": "/bin/false", "delta": "0:00:00.006289", "end": "2021-08-05 22:09:40.799988", "msg": "non-zero return code", "rc": 1, "start": "2021-08-05 22:09:40.793699", "stderr": "", "stderr_lines": [], "stdout": "", "stdout_lines": []}

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

若此时需要强制执行handlers中的内容，需要使用force_handlers: yes 参数，playbook修改如下：

[root@xuzhichao playbook]# cat force_handlers.yml
- hosts: localhost
  force_handlers: yes

  tasks:
    - name: Copy Configure File
      template:
        src: conf/nginx.conf.j2
        dest: /tmp/nginx.conf
      notify: Start Nginx

    - name: Igonre False
      shell: /bin/false

  handlers:
    - name: Start Nginx
      service:
        name: nginx
        state: started

此时运行playbook，当conf/nginx.conf.j2文件发生改变时，handlers将会被强制执行：

[root@xuzhichao playbook]# ansible-playbook force_handlers.yml 

PLAY [localhost] **********************************************************************************************************************************************

TASK [Copy Configure File] ************************************************************************************************************************************
changed: [localhost]

TASK [Igonre False] *******************************************************************************************************************************************
fatal: [localhost]: FAILED! => {"changed": true, "cmd": "/bin/false", "delta": "0:00:00.003843", "end": "2021-08-05 22:12:00.335807", "msg": "non-zero return code", "rc": 1, "start": "2021-08-05 22:12:00.331964", "stderr": "", "stderr_lines": [], "stdout": "", "stdout_lines": []}

RUNNING HANDLER [Start Nginx] *********************************************************************************************************************************
ok: [localhost]

PLAY RECAP ****************************************************************************************************************************************************
localhost                  : ok=2    changed=1    unreachable=0    failed=1    skipped=0    rescued=0    ignored=0

1.3 控制Tasks报告状态为OK

有时一些task会在每次playbook运行是都会执行一次，这样会导致playbook的运行结果中该task会显示为changed状态，但是有时这些task并没有改变被控端的状态，仅仅是获取了某些信息，此时可以使用changed_when: false 来抑制这个状态。

请看下面示例：

playbook文件内容如下：

[root@xuzhichao playbook]# cat status_ok.yml
- hosts: localhost
  tasks:
    - name: Get Nginx Server Port
      shell: netstat -ntlp | grep nginx
      register: nginx_port

    - name: Print Nginx Port
      debug:
        msg: 
          - "{{ nginx_port.stdout_lines }}"

每次的执行结果“Get Nginx Server Port”任务状态都是changed：

[root@xuzhichao playbook]# ansible-playbook status_ok.yml 

PLAY [localhost] **********************************************************************************************************************************************

TASK [Get Nginx Server Port] **********************************************************************************************************************************
changed: [localhost]     <==状态为changed

TASK [Print Nginx Port] ***************************************************************************************************************************************
ok: [localhost] => {
    "msg": [
        [
            "tcp        0      0 0.0.0.0:80              0.0.0.0:*               LISTEN      26579/nginx: master "
        ]
    ]
}

PLAY RECAP ****************************************************************************************************************************************************
localhost                  : ok=2    changed=1    unreachable=0    failed=0    skipped=0    rescued=0    ignored=0

可以使用changed_when: false 来抑制这个状态，playbook修改如下：

[root@xuzhichao playbook]# cat status_ok.yml
- hosts: localhost
  tasks:
    - name: Get Nginx Server Port
      shell: netstat -ntlp | grep nginx
      register: nginx_port
      changed_when: false     <==该task不再发生changed提示

    - name: Print Nginx Port
      debug:
        msg: 
          - "{{ nginx_port.stdout_lines }}"

此时执行结果如下：

[root@xuzhichao playbook]# ansible-playbook status_ok.yml 

PLAY [localhost] **********************************************************************************************************************************************

TASK [Get Nginx Server Port] **********************************************************************************************************************************
ok: [localhost]     <==变为OK状态

TASK [Print Nginx Port] ***************************************************************************************************************************************
ok: [localhost] => {
    "msg": [
        [
            "tcp        0      0 0.0.0.0:80              0.0.0.0:*               LISTEN      26579/nginx: master "
        ]
    ]
}

PLAY RECAP ****************************************************************************************************************************************************
localhost                  : ok=2    changed=0    unreachable=0    failed=0    skipped=0    rescued=0    ignored=0

1.4 changed_when检查任务结果

仍然以安装httpd为例，在每次修改完httpd的配置文件后，都需要检查配置文件的语法是否正确，如果不正确，则退出后续task，不重启httpd服务。

playbook文件优化如下：

[root@xuzhichao playbook]# cat change_when.yml
---
- hosts: 192.168.20.23
  remote_user: root

  tasks:
    - name: Install Htttpd Server
      yum:
        name: httpd
        state: present
      tags:
        - install_httpd
        - install_apache

    - name: Configure Httpd Server
      copy: 
        src: conf/httpd.conf.j2
        dest: /etc/httpd/conf/httpd.conf
        owner: "root"
        group: "root"
        mode: "0644"
      notify: Restart Httpd Server
      tags: conf_httpd

    - name: Check Httpd Configuer        <==检测配置文件语法
      shell: /usr/sbin/httpd -t
      register: httpd_check
      changed_when:
        - httpd_check.stdout.find('OK')  <==查找变量返回的结果是否有ok，如不存在则终止该tasks
        - false     <==被管理主机没有发生变化状态则为OK

    - name: Init Httpd Server
      copy:
        src: file/test.html.j2
        dest: /var/www/html/test.html
        owner: "apache"
        group: "apache"
        mode: "0644"
      tags: init_httpd

    - name: Start Httpd Server
      service:
        name: httpd
        state: started
        enabled: yes
      tags: start_httpd

  handlers:
    - name: Restart Httpd Server
      service:
        name: httpd
        state: restarted
      tags: restart httpd
      

[root@nginx03 ~]# httpd -t
Syntax OK

playbook运行结果如下：

[root@xuzhichao playbook]# ansible-playbook change_when.yml 

PLAY [192.168.20.23] ******************************************************************************************************************************************

TASK [Install Htttpd Server] **********************************************************************************************************************************
ok: [192.168.20.23]

TASK [Configure Httpd Server] *********************************************************************************************************************************
ok: [192.168.20.23]

TASK [Check Httpd Configuer] **********************************************************************************************************************************
ok: [192.168.20.23]

TASK [Init Httpd Server] **************************************************************************************************************************************
ok: [192.168.20.23]

TASK [Start Httpd Server] *************************************************************************************************************************************
changed: [192.168.20.23]

PLAY RECAP ****************************************************************************************************************************************************
192.168.20.23              : ok=5    changed=1    unreachable=0    failed=0    skipped=0    rescued=0    ignored=0

posted @ 2021-08-18 17:39 向往自由的独行者阅读(1772) 评论(0) 编辑收藏举报

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