Ansible的Playbook的编写
在Ansible中，将各个模块组合起来成为一个YAML格式的配置文件，这个配置文件叫做Playbook，
Playbook和模块的关系类似于shell脚本和Linux命令之间的关系。
Playbook的定义
一个Playbook可以包含多个Play，一个Play必须包含:
- hosts 定义在哪些服务器上执行
- tasks 定义执行列表，task的语法：module: options
当options较长时可以采用缩进子块的形式。
一个Playbook可以使用导入其它的Playbook
---
- inclued: db.yml
- include: web.yml
使用ansible-playbook执行Playbook
ansible的命令行参数：
- -T TIMEOUT, --timeout=TIMEOUT 建立SSH的超时时间
- --private-key=PRIVATE_KEY_FILE SSH的私钥文件
- -i INVENTORY, --inventory=INVENTORY 指定inventoey文件
- -f FORKS, --forks=FORKS 并发的进程数，默认是5
- --list-hosts 匹配到的服务器列表
- --list-tasks task列表
- --step 每执行一个tasks暂停，等待用户确认
- --syntax-check 检查palybook的语法
- -C, --check 检查是否会修改远程服务器，相当于预测执行结果
Playbook定义变量
Ansible有多种定义变量的方法，对于playbook，最简单的就是定义在Playbook的vars项中;
- hosts
vars:
mysql_port: 80
当变量多时，可以保存在一个独立的文件中
--- - hosts: all vars: mysql_prot: 80 vars_file: - /vars/external_vars.yml
变量文件的格式：
--- process: 2000 username: scott
注册变量
通过register获取上条命令的执行结果。并在下一个task中引用该变量
- hosts: webservers
tasks:
- shell: /usr/bin/foo
register: foo_result
ignore_errors: True
- shell: /usr/bin/bar
when: foo_result.rc == 5
Facts变量：
在Ansible中有些变量不需要进行任何设置就能直接使用，这些变量叫做Facts变量。
这些变量是Ansible从远程服务器上获取的系统信息。
可以通过setup模块查看。
ansible webservers -m setup
在Playbook中默认是收集远程机器信息的，可以设置为no，提高Ansible的执行效率。
-- hosts: dbservers
gather_facts: no
循环：
---
- name: Install Mysql package
yum: name={{ item }} state=installed
with_items:
- mysql-server
- Mysql-python
条件：
---
- hosts: webservers
tasks:
- command: echo {{ item }}
with_items: [ 0,2,4,6,8]
when: item > 5
执行结果;
实例：
使用Playbook部署nginx
---
- hosts: webservers
become: yes
become_method: sudo
vars:
worker_connections: 1024
worker_processes: 4
max_open_files: 65506
tasks:
- name: install nginx
yum: name=nginx update_cache=yes state=present
- name: copy nginx config file
template: src=/root/study/Ansible/nginx.conf.j2 dest=/etc/nginx/nginx.conf
notify: restart nginx
- name: copy index.html
template:
src: /root/study/Ansible/index.html.j2
dest: /usr/share/nginx/www/index.html
mode: 0644
notify: restart nginx
handlers:
- name: restart nginx
service: name=nginx state=restarted
jinjia2模板文件：
nginx.conf.j2
worker_processes {{ worker_processes }};
worker_rlimit_nofile {{ max_open_files }};
events {
worker_connections {{ worker_connections }};
}
http {
server {
listen 80 default_server;
listen [::]:80 default_server ipv6only=on;
listen 443 ssl;
root /usr/share/nginx/html;
index index.html index.htm;
server_name localhost;
location / {
try_files $uri $uri/ =404;
}
}
}
index.html.j2
<html>
<head>
<title>Welcome to ansible</title>
</head>
<body>
<h1>nginx, configured by Ansible</h1>
<p>If you can see this, Ansible successfully installed nginx.</p>
<p>{{ ansible_hostname }}</p>
</body>
</html>
部署MongoDB
---
- hosts: dbservers
become: yes
become_method: sudo
vars:
mongodb_datadir_prefix: /data
mongod_port: 27018
tasks:
- name: Create the mongodb user
user: name=mongodb comment="MongoDB"
- name: Create the data directory for the namenode metadata
file: path={{ mongodb_datadir_prefix }} owner=mongodb group=mongodb state=directory
- name: Install the mongodb package
apt: name={{ item }} state=installed
with_items:
- mongodb-server
- mongodb-clients
- rsyslog-mongodb
- name: create data directory for mongodb
file:
path: "{{ mongodb_datadir_prefix }}/mongo-{{ ansible_hostname }}"
state: directory
owner: mongodb
group: mongodb
- name: create log directory for mongodb
file: path=/var/log/mongo state=directory owner=mongodb group=mongodb
- name: Create the mongodb startup file
template: src=mongod.j2 dest=/etc/init.d/mongod-{{ ansible_hostname }} mode=0655
- name: Create the mongodb configuration file
template: src=mongod.conf.j2 dest=/etc/mongod-{{ ansible_hostname }}.conf
- name: Copy the keyfile for authentication
copy: src=secret dest={{ mongodb_datadir_prefix }}/secret owner=mongodb group=mongodb mode=0400
- name: Start the mongodb service
command: creates=/var/lock/subsys/mongod-{{ ansible_hostname }} /etc/init.d/mongod-{{ ansible_hostname }} start
配置文件：mongod.conf.j2
# mongo.conf
smallfiles=true
#where to log
logpath=/var/log/mongo/mongod-{{ ansible_hostname }}.log
logappend=true
# fork and run in background
fork = true
port = {{ mongod_port }}
dbpath={{ mongodb_datadir_prefix }}mongo-{{ ansible_hostname }}
keyFile={{ mongodb_datadir_prefix }}/secret
# location of pidfile
pidfilepath=/var/run/mongod-{{ ansible_hostname }}.pid
另外还可以将Playbook抽象成role。
可以参考https://galaxy.ansible.com，下载别人写好的role
初始化role
ansible-galaxy init /etc/ansible/roles/websrvs
安装别人写好的role
ansible-galaxy install -p /etc/ansible/roles bennojoy.mysql
