ansible——处理任务失败

1.忽略任务失败

Ansible 默认会检查命令和模块的返回状态，并进行相应的错误处理，默认是遇到错误就中断 playbook 的执行，这些默认行为都是可以改变的，可以通过 ignore_errors 忽略返回状态码

---
 - name: test
  hosts: rhel8_no1.test.com
  tasks:
    - name: install packages
      yum:
         name: haha   ##不存在的安装包
         state: latest
      ignore_errors: yes    ##忽略错误

2.任务失败后强制执行处理程序

通常任务失败，playbook 会终止，那么收到 play 中之前任务通知的处理程序将不会运行，如果要运行，需要使用关键字：force_handlers：yes

--- 
 - hosts: rhel8_no1.test.com
  force_handlers: yes   ##强制执行处理任务
  tasks: 
      - name: always notify 
        command: /bin/true 
        notify: restart apache 
      - name: Fail task 
        yum: 
             name: haha    ##错误任务
             state: latest 
  handlers: 
          - name: restart apache 
             service: 
                 name: httpd
                 state: restarted

3.指定任务失败条件

关键字：failed_when

 - hosts: rhel8_no1.test.com
  tasks: 
     - name: Run Script 
       shell: /usr/local/bin/user.sh 
       register: command_result 
       failed_when: "'failure' in command_result.stdout"   ##如果命令输出结果中有failure字符串，则任务失败

fail 模块也可以实现此效果

 - hosts: rhel8_no1.test.com
   tasks: 
       - name: Run Script 
         shell: /usr/local/bin/user.sh 
         register: command_result 
         ignore_error: yes 
       - name: Report failure 
         fail: 
             msg: "Authentication failure"    ##fail 模块可以提供明确消息 
         when: "'failure' in command_result.stdo"

4.指定任务何时报告"Changed"结果

关键字：changed_when

 - hosts: rhel8_no1.test.com
   tasks: 
       - name: get time
         shell: date
         changed_when: false   ##不报告changed结果

5.ansible 块和错误处理

三种关键字：

• block：定义要运行的主要任务
• rescue：定义要在 block 子句中定义的任务失败时运行的任务
• always：定义始终独立运行的任务

---
- name: Task  Failure
  hosts: rhel8_no1.test.com
  vars:
     web_pkg: http    ##错误安装包
     db_pkg: mariadb-server
     db_service: mariadb
  tasks:
    - name: Set up web
      block:
        - name: install {{web_pkg}} packages
          yum:
           name: "{{web_pkg}}"        ##任务执行失败
           state: present
      rescue:
        - name: install {{db_pkg}} packages
          yum:
           name: "{{db_pkg}}"    ##执行rescue模块
           state: present
      always:
        - name: start ::db_service}} service
          serbice:
             name: "{{db_service}}"     ##始终执行
             state: started

设定变量 web_pkg: httpd,使block模块正常执行，忽略rescue模块，always总是执行