ansible with_items用法

当有需要重复性执行的任务时，可以使用迭代机制。

迭代 with_items(loop)

• 对迭代项的引用，固定内置变量名为”item”
• 要在task中使用with_items给定要迭代的元素列表
• 注意: ansible2.5版本后，可以用loop代替with_items
• 列表元素格式：字符串、字典

范例

批量创建用户

---
  - hosts: webservers

    tasks:
      - name: add several users
        user: name={{ item }} state=present group=nobody
        with_items:
          - testuser1
          - testuser2
          - testuser3

批量卸载mariadb文件

---
- hosts: webservers
  tasks:
    - name: Stop service
      shell: /etc/init.d/mysqld stop
    - name: Delete files
      file: path={{ item }} state=absent
      with_items:
        - /usr/local/mysql
        - /usr/local/mariadb-10.2.27-linux-x86_64
        - /etc/init.d/mysqld
        - /etc/profile.d/mysql.sh
        - /etc/my.cnf
    - name: Delete user
      user: name=mysql state=absent remove=yes

安装多个软件包时，不建议使用循环

---
#yum使用循环会提示warning
- hosts: webservers
  tasks:
    - name: Install packages
      yum: name={{ item }} state=present
      with_items:
        - nginx
        - sl
        - php-fpm

警告信息

[DEPRECATION WARNING]: Invoking "yum" only once while using a loop via squash_actions is deprecated. Instead of using a loop to supply multiple items and specifying `name: "{{ item }}"`, please use `name: ['nginx', 'sl', 'php-fpm']` and remove the loop. This feature will be removed in version 2.11. Deprecation warnings can be disabled by setting deprecation_warnings=False in ansible.cfg.xxxxxxxxxx [DEPRECATION WARNING]: Invoking "yum" only once while using a loop via squash_actions is deprecated. Instead of using a loop to supply multiple items and specifying `name: "{{ item }}"`, please use `name: ['nginx', 'sl', 'php-fpm']` and remove the loop. This feature will be removed in version 2.11. Deprecation warnings can be disabled by setting deprecation_warnings=False in ansible.cfg.1

解决办法是：直接用列表列出软件包

---
#不使用循环
- hosts: webservers
  tasks:
    - name: Install packages
      yum:
        name: [nginx,sl,php-fpm]
        state: present

批量复制文件

---
- hosts: webservers
  tasks:
    - name: Copy file
      copy: src={{ item }} dest=/tmp/{{ item }}
      with_items: 
        - file1
        - file2
        - file3

迭代嵌套子变量

在迭代中，还可以嵌套子变量，关联多个变量在一起使用。

范例

批量创建组和用户并指定uid

---
- hosts: webservers
  tasks:
    - name: Create group
      group: name={{ item }} state=present 
      with_items:
        - group1
        - group2
        - group3
    - name: Create user
      user: name={{ item.user }} state=present group={{ item.group }} create_home=no uid={{ item.uid }}
      with_items:
        - {user: "user1", group: "group1", uid: "1111"}
        - {user: "user2", group: "group2", uid: "2222"}
        - {user: "user3", group: "group3", uid: "3333"}

util循环

until为false时才会执行循环，为true则退出循环。

范例

显示5次信息后退出

---
- hosts: webservers
  tasks:
    - debug: 
        msg: "until"
      until: false
      retries: 5

with_lines 逐行处理

显示进程信息

---
- hosts: webservers
  tasks:
    - debug:
        msg: "{{ item }}"
      with_lines: ps aux