Ansible Playbook是基于Yaml语法的ansible命令文件，简单来说，可以理解为linux的普通命令和shell脚本的区别，通过playbook，可以实现更复杂的操作。
下面是一个部署nfs远程挂载的ansible playbook

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---
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- name: setup nfs server
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  hosts: nfs
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  tasks:
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    - name: 01 - install nfs-utils
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      yum:
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        name: nfs-utils
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        state: installed
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    - name: 02 - install rpcbind
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      yum:
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        name: rpcbind
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        state: installed
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    - name: 03 - start and enable nfs-utils
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      systemd:
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        name: nfs-utils
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        state: started
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        enabled: true
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    - name: 04 - start and enable rpcbind
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      systemd:
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        name: rpcbind
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        state: started
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        enabled: true
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    - name: 05 - setup nfs configuration
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      shell:
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        cmd: "echo '/data 172.16.1.0/24(rw,sync,all_squash)' >> /etc/exports"
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    - name: 06 - change wordpress file user and group
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      file:
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        path: /data
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        state: directory
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        owner: nfsnobody
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        group: nfsnobody
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        recurse: true
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    - name: 09 - start and enable nfs
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      systemd:
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        name: nfs
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        state: started
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        enabled: true
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- name: mount wordpress files to web server
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  hosts: web
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  tasks:
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    - name: 01 - install rpcbind
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      yum:
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        name: rpcbind
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        state: installed
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    - name: 02 - install nfs-utils
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      yum:
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        name: nfs-utils
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        state: installed
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    - name: 03 - start and enable nfs-utils
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      systemd:
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        name: nfs-utils
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        state: started
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        enabled: true
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    - name: 04 - create mount directory
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      file:
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        path: /www
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        state: directory
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    - name: 05 - restart rpcbind
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      systemd:
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        name: rpcbind
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        state: restarted
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        enabled: true
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    - name: 06 - mount
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      mount:
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        src: 172.16.1.31:/wordpress
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        path: /www
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        fstype: nfs
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        state: mounted

从这个playbook可以看出，部分内容是重复的，但是通过playbook的高级用法可以更简单的实现相同的功能。

Loop循环#

使用loop关键字定义循环变量
使用item关键字提取loop每次循环出来的值

以nfs服务器中安装nfs-utils和rpcbind为例，使用loop可以让我们在一个模块中安装两个应用。

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---
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- name: install nfs-utils and rpcbind
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  hosts: nfs
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  tasks:
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    - name: installation
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      yum:
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        name: "{{ item }}"
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        state: installed
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      loop:
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        - nfs-utils
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        - rpcbind

如此一来，我们就实现了通过循环安装多个软件。
但是，可以发现我们后面一样要通过systemd模块来运行并为这两个应用设置开机自启；目前loop循环是置于name: installation下面，没办法在其他的模块中使用，因此，引入下一个概念：vars

使用vars定义循环列表#

通过vars关键字我们可以为循环配置一个变量名，让这个循环可以被同级的任何一个模块使用。

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---
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- name: setup nfs applications
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  hosts: nfs
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  vars:
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    app:
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      - nfs-utils
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      - rpcbind
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  tasks:
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    - name: installation
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      yum:
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        name: "{{ item }}"
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        state: installed
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      loop: "{{ app }}"
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    - name: start and set enabled
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      systemd:
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        name: "{{ item }}"
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        state: started
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        enabled: true
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      loop: "{{ app }}"

循环处理字典数据#

假如我要创建三个文件，他们的属主各不相同，应该如果实现呢？

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---
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- name: create files for three different users
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  hosts: web
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  tasks:
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  - name: create files
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    file:
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      path: "{{ item.path }}"
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      state: touch
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      owner: "{{ item.owner }}"
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    loop:
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      - {path: '/opt/mike.txt', owner: mike}
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      - {path: '/opt/sarah.txt', owner: sarah}
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      - {path: '/opt/john.txt', owner: john}

当然，字典循环也可以被声明成一个变量，和之前的差不多，就不加赘述了。

Register将模块的输出结果注册为变量#

Register可以将模块的执行结果注册为一个变量，并通过debug模块中的.stdout_lines输出到ansible管理终端。
例如，我想要知道一个文本文件中有多少行：

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---
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- name: how many lines for the text file
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  hosts: 172.16.1.105
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  tasks:
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  - name: count lines
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    shell:
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      cmd: "cat /opt/testfile.txt | wc -l"
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    register: lines
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  - name: output the value
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    debug:
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      msg: "{{ lines.stdout_lines }}"

注册多个变量并和loop结合使用#

在之前的基础上再查看一下目标主机名

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---
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- name: register and loop
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  hosts: 172.16.1.105
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  tasks:
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  - name: count lines
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    shell:
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      cmd: "cat /opt/testfile.txt | wc -l"
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    register: lines
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  - name: show hostname
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    shell:
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      cmd: "cat /etc/hostname"
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    register: hostname
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  - name: output the value
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    debug:
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      msg: "{{ item }}"
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    loop:
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      - lines.stdout_lines
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      - hostname.stdout_lines

When条件判断#

when通常和register组合使用，以实现通过判断执行结果来指定后续操作。
以查看文件为例：

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---
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- name: how many lines for the text file
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  hosts: 172.16.1.105
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  tasks:
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  - name: count lines
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    shell:
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      cmd: "cat /opt/testfile.txt"
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    ignore_errors: true
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    register: result
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  - name: output the value
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    debug:
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      msg: "FATAL: File does not exists"
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    when: result is failed

ignore_errors: 忽略报错继续向后执行

与ansible的内置变量相结合，还可以实现更多的有趣的功能；比如我想为web主机组下的所有主机创建一个文件，但其中一台主机不包括在内，这就可以用内置变量加条件判断的方法来实现：

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---
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- name: how many lines for the text file
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  hosts: web
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  tasks:
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  - name: count lines
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    file:
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      path: /opt/file.txt
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      state: touch
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    when: inventory_hostname != "172.16.1.7"

inventory_hostname: 目标主机名 - 取决于你在hosts文件中是如何配置的(ip或者别名)

Notify和Handler#

当调用某个任务确实执行了，且状态changed为true，notify就会执行指定的handler事件
还是以创建文件为例：

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---
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- hosts: web
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    tasks:
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    - name: create file
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        file:
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        path: /opt/testfile.txt
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        state: touch
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        mode: 600
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        notify:
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        - output message
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    handlers:
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    - name: output message
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        debug:
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        msg: "File created"

使用Tags为不同的task打标签，实现剧本的部分执行#

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- name: deploy nfs
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    hosts: nfs
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    tasks:
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    - name: 01 - install nfs-utils
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    yum: name=nfs-utils state=installed
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    tags: 01_install_nfs_service
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    - name: 02 - install rpcbind
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    yum: name=rpcbind state=installed
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    tags: 02_install_rpcbind_service
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    - name: 03 - create group
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    group: name=www gid=666
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    tags: 03_add_group
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    - name: 04 - create user
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    user: name=www uid=666 group=www create_home=no shell=/sbin/nologin
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    tags: 04_add_user

显示剧本的所有tag标签：

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ansible-playbook --list-tags playbook.yml

使用-t参数根据tag执行部分剧本：

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ansible-playbook -t tag名 playbook.yml

对一开始的部署nfs挂载剧本进行改造#

1
---
2
- name: setup nfs server
3
  hosts: nfs
4
  vars:
5
    app:
6
      - nfs-utils
7
      - rpcbind
8
  tasks:
9
    - name: 01 - install apps
10
      yum:
11
        name: "{{ item }}"
12
        state: installed
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      loop: "{{ app }}"
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    - name: 02 - start and enable apps
15
      systemd:
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        name: "{{ item }}"
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        state: started
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        enabled: true
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      loop: "{{ app }}"
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    - name: 03 - setup nfs configuration
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      shell:
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        cmd: "echo '/data 172.16.1.0/24(rw,sync,all_squash)' >> /etc/exports"
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      notify:
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        - start NFS
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      handlers:
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        - name: start NFS
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          systemd:
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            name: nfs
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            state: started
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            enabled: true
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    - name: 04 - change wordpress file user and group
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      file:
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        path: /data
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        state: directory
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        owner: nfsnobody
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        group: nfsnobody
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        recurse: true
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- name: mount directory to web server
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  hosts: web
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  vars:
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    app:
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      - nfs-utils
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      - rpcbind
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  tasks:
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    - name: 01 - install apps
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      yum:
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        name: "{{ item }}"
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        state: installed
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      loop: "{{ app }}"
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    - name: 02 - start and enable apps
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      systemd:
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        name: "{{ item }}"
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        state: started
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        enabled: true
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      loop: "{{ app }}"
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    - name: 03 - create mount directory
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      file:
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        path: /www
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        state: directory
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    - name: 04 - mount
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      mount:
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        src: 172.16.1.31:/data
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        path: /www
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        fstype: nfs
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        state: mounted

Ansible-playbook高级用法