第四章：jianja2模板用法

第一节：jinja2介绍

Jinja2是基于python的模板引擎，功能比较类似于PHP的smarty，J2ee的Freemarker和velocity。它能完全支持unicode，并具有集成的沙箱执行环境，应用广泛。jinja2使用BSD授权

第二节：jianja2判断语句

{% if EXPR %}...{% elif EXPR %}...{% endif%} 作为条件判断

1.EXAMPLE:

{% if ansible_fqdn == "web01" %}
 echo "123"
 {% elif ansible_fqdn == "web02" %}
 echo "456"
 {% else %}
 echo "789"
 {% endif %}

2.jianja2渲染keepalived配置文件

[root@m01 /roles]# cat keepalived/templates/keepalived.conf.j2
 global_defs {
 router_id {{ ansible_hostname }}
 }
 ​
 vrrp_script check_web {
 script "/server/scripts/check_web.sh"
 interval 5
 weight 50
 }
 ​
 {% if ansible_hostname == "lb03" %}
 vrrp_script check_vip {
 script "/server/scripts/check_vip.sh"
 interval 5
 weight 50
 }
 {% endif %}
 ​
 vrrp_instance VI_1 {
 state {{ state }}
 interface eth0
 virtual_router_id 50
 priority {{ priority }}
 advert_int 1
 authentication {
 auth_type PASS
 auth_pass 1111
 }
 virtual_ipaddress {
 10.0.0.3
 }
 track_script {
 check_web
 {% if ansible_hostname == "lb03" %}
 check_vip
 {% endif %}
 }
 }

第三节：jianja2循环语句

1.EXAMPLE

{% for i in EXPR %}...{% endfor%} 作为循环表达式
 {% for i in range(1,10) %}
 server 172.16.1.{{i}};
 {% endfor %}
 {# COMMENT #} 表示注释

2.jinja2 渲染 nginx_proxy配置文件

[root@m01 project1]# cat kod_proxy.conf.j2
 upstream web_pools {
 {% for i in range(1,10) %}
 server 172.16.1.{{i}}:{{http_port}} weight=2;
 {% endfor %}
 }
 ​
 server {
 listen 80;
 server_name web_pools;
 location / {
 proxy_pass http://{{ server_name }};
 include proxy_params;
 }
 }

第四节：jinja循环高级用法

1.循环inventory主机清单(hosts文件)中的webserver组,将提取到的IP赋值给i变量.

upstream web_pools {
 {% for i in groups['webserver'] %}
 server {{i}}:80;
 {% endfor %}

2.官方举例

{% for host in groups['app_servers'] %}
 
 
something that applies to all app servers.
 
 
{% endfor %}

https://docs.ansible.com/ansible/latest/user_guide/playbooks_variables.html

3.Inventory中的host_vars根据不同主机设定不同的变量。

[root@m01 project1]# cat host_vars/172.16.1.5
 state: MASTER
 prioroty: 150
 [root@m01 project1]# cat host_vars/172.16.1.6
 state: BACKUP
 prioroty: 100

4.判断变量是否有值

- hosts: webservers
 gather_facts: no
 vars:
 PORT: 13306
 tasks:
 
 
 
  
name: Copy MySQL Configure
 template:
 src: my.cnf.j2
 dest: /tmp/my.cnf
 ​
 [root@m01 project1]# cat my.cnf.j2
 {% if PORT %}
 bind-address=0.0.0.0:{{ PORT }}
 {% else %}
 bind-address=0.0.0.0:3306
 {% endif %}