Ansible中任务的执行控制方法

循环

循环迭代任务

1.简单循环

loop:
  - westosdir1
  - westosdir2   
  - westosdir3
  ...

迭代变量名称: {{item}}
实例：
在172.25.29.1中创建目录westosdir1、westosdir2、westosdir3
vim loop.yml

---
- name: loop
  hosts: 172.25.29.1
  tasks:
    - name: directory create
      file:
        name: /mnt/{{item}}
        state: directory
      loop:
        - westosdir1
        - westosdir2
        - westosdir3

运行结果

2、循环散列或字典列表

实例:将httpd服务重启，并将防火墙关闭

---
- name: loop
  hosts: 172.25.29.1
  tasks:
    - name: service control
      service:
        name: "{{item.service}}"
        state: "{{item.state}}"
      loop:
        - service: httpd
          state: restarted
        - service: firewalld
          state: stopped

条件控制

when：
  - 条件1
  - 条件2

条件判断

条件	判断
=	value == ”字符串“,value = 数字
<	value < 数字
>	value > 数字
<=	value <= 数字
>=	value >= 数字
!=	value !=数字
is defined value	value is defined 变量存在
is not defined	value is not defined 变量不存在
bool变量为true	value value的值为true

实例1

---
- name: when
  hosts: 172.25.29.1
  tasks:
    - name: echo westos
      shell: echo westos
      register: echo_westos
      ignore_errors: yes

    - name: debug
      debug:
        msg: "{{echo_westos.rc}}"
      when: echo_westos.rc ==1

实例2

---
- name: when
  hosts: 172.25.29.1
  tasks:
    - name: debug
      debug:
        msg: "{{ansible_facts['br0']['ipv4']['address']}}"
      when: ansible_facts.br0.ipv4 is defined

触发器

notify和handlers

notify:触发器当遇到更改时触发handlers动作
handlers: 触发器触发后执行的动作
实例

---
- name: handlers
  hosts: 172.25.29.1
  tasks:
    - name: restart firewalld
      service:
        name: firewalld
        state: restarted
      notify:
        - debug ipv4
  handlers:
    - name: debug ipv4
      debug:
        msg: "{{ansible_facts['br0']['ipv4']['address']}} firewalld is restarted"

对照

---
- name: handlers
  hosts: 172.25.29.1
  tasks:
    - name: restart firewalld
      service:
        name: firewalld
        state: started
      notify:
        - debug ipv4
  handlers:
    - name: debug ipv4
      debug:
        msg: "{{ansible_facts['br0']['ipv4']['address']}} firewalld is restarted"

force_handlers

作用：当任务失败后play被终止也会调用触发器进程
实例

---
- name: handlers
  hosts: 172.25.29.1
  force_handlers: yes
  tasks:
    - name: restart firewalld
      service:
        name: firewalld
        state: restarted
      notify:
        - debug ipv4

    - name: error
      dnf:
        name: westos
        state: latest
  handlers:
    - name: debug ipv4
      debug:
        msg: "{{ansible_facts['br0']['ipv4']['address']}} firewalld is restarted"

changed_when

作用：控制任务在何时报告它已进行更改
实例

- name: change
  host: 192.168.43.33
  tasks: 
    - name: start
      service:
        name: firewalld
        start: started
      change_when: true
      notify:
        debug
  handlers:
    - name: debug
      debug:
        msg: "{{ansible_facts['ens160']['ipv4']['address']}}"

- name: change
  host: 192.168.43.33
  tasks: 
    - name: start
      service:
        name: firewalld
        start: started
      change_when: false
      notify:
        debug
  handlers:
    - name: debug
      debug:
        msg: "{{ansible_facts['ens160']['ipv4']['address']}}"

failed_when

作用： 当符合条件时强制任务失败

---
- name: failed
  hosts: all
  tasks:
     - name:
       shell: echo westos
       register: westos
       failed_when: "{{ansible_facts}} is not defined"

---
- name: failed
  hosts: all
  tasks:
     - name:
       shell: echo westos
       register: westos
       failed_when: "{{ansible_facts}} is defined"

block

block: 定义要运行的任务
rescue： 定义block句子中出现失败任务后运行的任务
always：定义最终独立运行的任务
实例

---
- name: block
  hosts: 
    192.168.43.33
    192.168.43.40
  tasks:
    - name: 192.168.43.33
      block: 
        - name dnf ansible
          dnf:
            name: ansible
            state: latest
      rescue:
        - name: show error
          debug: 
            msg: "{{ansible_facts['ens160']['ipv4']['address']}} is install error"
      always:
        - shell: echo westos