Ansible 笔记 (3) - 编写 playbook

playbook 相当于多个命令的编排组合然后一起运行，类似写脚本。在学习 playbook 之前需要了解 yaml 格式。

编写playbook的步骤：

• 定义主机与用户
• 编写任务列表
• 执行 playbook

当然 playbook 支持拆分多个文件，并且可以使用多种维度的封装，例如定义变量、任务、处理程序等，鼓励代码/文件复用。

下面是安装 nginx 和 ntp server 的示例。

1、文件目录结构

[root@localhost ansible_demo]# tree nginx_ntp/
nginx_ntp/
├── group_vars
│   ├── all
│   └── webserver
├── hosts
├── roles
│   ├── common
│   │   ├── handlers
│   │   │   └── main.yml
│   │   ├── tasks
│   │   │   └── main.yml
│   │   ├── templates
│   │   │   └── ntp.conf.j2
│   │   └── vars
│   │       └── main.yml
│   └── web
│       ├── handlers
│       │   └── main.yml
│       ├── tasks
│       │   └── main.yml
│       └── templates
│           └── nginx2.conf
└── site.yml
 
11 directories, 11 files

2、Inventory 文件

[root@localhost nginx_ntp]# cat hosts
[webserver]
192.168.34.129
192.168.34.130

3、playbook 入口文件

[root@localhost nginx_ntp]# cat site.yml
---
- name: apply common configuration to all nodes
  hosts: all
  roles:
    - common
 
- name: configure and deploy the webserver and application code
  hosts: webserver
  roles:
    - web

4、组变量文件

根据 inventory 来区分，all 表示所有，webserver 则指 hosts 中的 webserver section

[root@localhost nginx_ntp]# cd group_vars/
[root@localhost group_vars]# ll
total 8
-rw-r--r--. 1 root root 32 Mar  6 18:12 all
-rw-r--r--. 1 root root 72 Mar  6 18:24 webserver
[root@localhost group_vars]# cat all
---
ntpserver: ntp.sjtu.edu.cn
 
[root@localhost group_vars]# cat webserver
---
worker_processes: 4
root: /data1
worker_connections: 1024
user: www

5、roles 设置

5.1、角色 common 配置，

安装 ntp server，配置文件并同步时间启动 ntp server

• 任务入口 tasks

[root@localhost nginx_ntp]# cd roles/common/tasks/
[root@localhost tasks]# cat main.yml
---
- name: install ntp server
  yum: name=ntp state=present
 
- name: set zone info
  shell: \cp -rf /usr/share/zoneinfo/Asia/Shanghai /etc/localtime 
 
- name: update time
  shell: ntpdate asia.pool.ntp.org
 
- name: configure ntp file
  template: src=ntp.conf.j2 dest=/etc/ntp.conf
  notify:
    - restart ntp
 
- name: start ntp server
  service: name=ntpd state=started enabled=true
 
- name: test to see if selinux is running
  command: getenforce
  register: sestatus
  changed_when: false

• name 为 configure ntp file 的任务运行后的 callback handlers

[root@localhost common]# cat handlers/main.yml
---
- name: restart ntp
  service: name=ntpd state=restarted

• template 源文件

[root@localhost common]# cat templates/ntp.conf.j2
driftfile /var/lib/ntp/drift
restrict 127.0.0.1
restrict -6 :: 1
 
server {{ ntpserver }}
includefile /etc/ntp/crypto/pw
keys /etc/ntp/keys

• role common 内置变量

[root@localhost common]# cat vars/main.yml
---
ntpserver: 210.72.145.44

5.2 角色 web 配置

安装 nginx，配置文件并启动

• 任务入口 tasks

[root@localhost web]# cat tasks/main.yml
---
 
- name: install nginx
  yum: name=nginx state=latest
 
- name: add user
  shell: useradd {{ user }}
 
- name: write config
  template: src=nginx2.conf dest=/etc/nginx/nginx.conf
  notify:
    - restart nginx
 
- name: ensure nginx is running
  shell: /usr/sbin/nginx -c /etc/nginx/nginx.conf

• name 为 write config 的任务运行后的 callback handlers

[root@localhost web]# cat handlers/main.yml
---
- name: restart nginx
  service: name=nginx state=restarted

• template 文件

[root@localhost web]# cat templates/nginx2.conf
user  www;
worker_processes  {{ worker_processes }};
 
events {
    worker_connections  {{ worker_connections }};
}
 
http {
    include       mime.types;
    default_type  application/octet-stream;
 
    sendfile        on;
    keepalive_timeout  65;
 
    server {
        listen       80;
        server_name  localhost;
        root         {{ root }};
 
        #charset koi8-r;
 
        #access_log  logs/host.access.log  main;
 
        location / {
            root   html;
            index  index.html index.htm;
        }
 
        #error_page  404              /404.html;
 
        # redirect server error pages to the static page /50x.html
        #
        error_page   500 502 503 504  /50x.html;
        location = /50x.html {
            root   html;
        }
    }
}

6 检查语法和运行

[root@localhost nginx_ntp]# ansible-playbook -i hosts site.yml --syntax-check
ERROR! Problem parsing file '/data1/ansible_demo/nginx_ntp/group_vars/all': line 2, column 1

发现 all 文件出错，修改后继续

[root@localhost nginx_ntp]# ansible-playbook -i hosts site.yml --syntax-check
 
playbook: site.yml
[root@localhost nginx_ntp]# ansible-playbook -i hosts site.yml -f 10
 
PLAY [apply common configuration to all nodes] **********************************************************************************************
 
TASK [Gathering Facts] **********************************************************************************************************************
ok: [192.168.34.130]
ok: [192.168.34.129]
 
TASK [common : install ntp server] **********************************************************************************************************
ok: [192.168.34.129]
ok: [192.168.34.130]
 
TASK [common : set zone info] ***************************************************************************************************************
changed: [192.168.34.130]
changed: [192.168.34.129]
 
TASK [common : update time] *****************************************************************************************************************
changed: [192.168.34.130]
changed: [192.168.34.129]
 
TASK [common : configure ntp file] **********************************************************************************************************
changed: [192.168.34.129]
changed: [192.168.34.130]
 
TASK [common : start ntp server] ************************************************************************************************************
changed: [192.168.34.130]
changed: [192.168.34.129]
 
TASK [common : test to see if selinux is running] *******************************************************************************************
ok: [192.168.34.130]
ok: [192.168.34.129]
 
RUNNING HANDLER [common : restart ntp] ******************************************************************************************************
changed: [192.168.34.129]
changed: [192.168.34.130]
 
PLAY [configure and deploy the webserver and application code] ******************************************************************************
 
TASK [Gathering Facts] **********************************************************************************************************************
ok: [192.168.34.130]
ok: [192.168.34.129]
 
TASK [web : install nginx] ******************************************************************************************************************
ok: [192.168.34.130]
ok: [192.168.34.129]
 
TASK [web : add user] ***********************************************************************************************************************
changed: [192.168.34.129]
changed: [192.168.34.130]
 
TASK [web : write config] *******************************************************************************************************************
changed: [192.168.34.129]
changed: [192.168.34.130]
 
TASK [web : ensure nginx is running] ********************************************************************************************************
changed: [192.168.34.129]
changed: [192.168.34.130]
 
RUNNING HANDLER [web : restart nginx] *******************************************************************************************************
changed: [192.168.34.129]
changed: [192.168.34.130]
 
PLAY RECAP **********************************************************************************************************************************
192.168.34.129             : ok=14   changed=9    unreachable=0    failed=0
192.168.34.130             : ok=14   changed=9    unreachable=0    failed=0   
 
[root@localhost nginx_ntp]# 

 7、被控机验证

[root@localhost yum.repos.d]# ps -ef | grep ntp
ntp                : ?        :: ntpd -u ntp:ntp -p /var/run/ntpd.pid -g
root            : pts/    :: grep ntp
[root@localhost yum.repos.d]# ps -ef | grep nginx
root               : ?        :: nginx: master process /usr/sbin/nginx -c /etc/nginx/nginx.conf
www            : ?        :: nginx: worker process
www            : ?        :: nginx: worker process
www            : ?        :: nginx: worker process
www            : ?        :: nginx: worker process
root            : pts/    :: grep nginx