jinja2模板语法

1)playbook文件使用template模块2)模板文件里面变量使用{{}}，比如{{PORT}}，或使用facts

{{ 变量名 }}   可以在配置文件中使用，也可以在playbook里用

仅可以在配置文件中使用{% if%}{% elif%}{% else%}{% endif%}
{% if $?== 0%}echo xxx{% else%}echo aaa{% endif%}

{% for 条件%}{% end 条件%}

例一：在motd文件调用变量/etc/motd：这个文件是在你登录之后显示的，不管你是 TTY 还是 PTS 登录，也不管是 Telnet 或 SSH 都会显示这个文件里面的信息。
# 准备playbook[root@m01 ~/ansible]# vim jinja2.yml- hosts: web_grouptasks: - name: 复制模板文件  template:     #//使用template模块    src: /root/ansible/motd.j2    dest: /etc/motd
# 准备要复制的文件motd.j2vim /root/ansible/motd.j2=========================================欢迎使用：{{ ansible_fqdn }}本机总内存：{{ ansible_memtotal_mb }}本机可用内存：{{ ansible_memfree_mb }}本机内网IP: {{ ansible_eth0 ['ipv4']['address'] }}=========================================
# 准备完成，执行Playbook[root@m01 ~/ansible]# lltotal 8-rw-r--r-- 1 root root 126 Oct  7 05:52 jinja2.yml-rw-r--r-- 1 root root 264 Oct  7 05:53 motd.j2[root@m01 ~/ansible]# ansible-playbook jinja2.yml...

## 执行Playbook后效果：每台机器登录时变量都会自动识别[root@web01 ~]# cat /etc/motd=========================================欢迎使用：web01本机总内存：972本机可用内存：145本机内网IP: 10.0.0.7=========================================
Last login: Mon Aug 14 08:11:23 2023 from 172.16.1.61=========================================欢迎使用：web01本机总内存：972本机可用内存：145本机内网IP: 10.0.0.7=========================================
#该示例展示了如何利用jinja2模板使用facts变量，达到我们想要的目的，实现自动化的需求

例二：使用jinja2模板的if判断渲染keepalived配置文件，并推送到不同lb主机上
#playbook：cat config_keepalived.yml- hosts: all  tasks:  - name: 下发keeepalived配置文件    template:      src: /root/ansible/keepalived/keepalived.j2      dest: /etc/keepalived/keepalived.conf    when: ansible_fqdn is match 'lb*' 
#配置文件cat /root/ansible/keepalived/keepalived.j2  #//不使用jinja2的话需要准备两份配置文件，MASTER的与BACKUPglobal_defs {    router_id {{ ansible_fqdn }}}
{% if ansible_fqdn == 'lb01' %}vrrp_script check_ngx {  script "/root/check_web.sh"  interval 5} 
vrrp_instance VI_1 {    track_script {      check_ngx        }    state MASTER    priority 150{% else %}vrrp_instance VI_1 {    state BACKUP    priority 100{% endif %}    interface eth0    virtual_router_id 50    advert_int 1    authentication {        auth_type PASS        auth_pass 1111    }    virtual_ipaddress {        10.0.0.3    }}

例三：使用jinja2的for循环管理nginx负载均衡配置文件#playbook[root@m01 ~/ansible]# vim lb_blog.yml- hosts: lb_group  vars:    nginx_port: 80    domain_name: blog.andrew.com    pool_name: blog_pools
  tasks:  - name: 下发nginx配置文件    template:      src: /root/ansible/blog_lb_conf.j2      dest: /opt/nginx.conf    notify: 重载nginx      handlers:    - name: 重载nginx      systemd:         name: nginx        state: reloaded
#配置文件[root@m01 ~/ansible]# vim blog_lb_conf.j2upstream {{ pool_name }} {    {% for number in range(7,17) %}    server 10.0.0.{{ number }}:{{ nginx_port }};    {% endfor %}}
server{    listen {{ nginx_port }};    server_name {{ domain_name }};    location  / {        proxy_pass http://{{ pool_name }};        include /etc/nginx/conf.d/proxy_params;    }}
#执行playbook[root@m01 ~/ansible]# ansible-playbook lb_blog.yml
#查看结果[root@lb01 /opt]# cat nginx.conf [root@lb02 /opt]# cat nginx.conf upstream blog_pools {        server 10.0.0.7:80;        server 10.0.0.8:80;        server 10.0.0.9:80;        server 10.0.0.10:80;        server 10.0.0.11:80;        server 10.0.0.12:80;        server 10.0.0.13:80;        server 10.0.0.14:80;        server 10.0.0.15:80;        server 10.0.0.16:80;    }
server{    listen 80;    server_name blog.andrew.com;    location  / {        proxy_pass http://blog_pools;        include /etc/nginx/conf.d/proxy_params;    }}

 例四：使用jinja2管理MySQL配置文件
[mysqld]datadir=/var/lib/mysqlsocket=/var/lib/mysql/mysql.socksymbolic-links=0innodb_buffer_pool_size=800M
[mysqld_safe]log-error=/var/log/mariadb/mariadb.logpid-file=/var/run/mariadb/mariadb.pid!includedir /etc/my.cnf.d

## 根据主机内存修改buffer pool[mysqld]datadir=/var/lib/mysqlsocket=/var/lib/mysql/mysql.socksymbolic-links=0innodb_buffer_pool_size={{ (ansible_memtotal_mb * 0.8)|int }}M
[mysqld_safe]log-error=/var/log/mariadb/mariadb.logpid-file=/var/run/mariadb/mariadb.pid!includedir /etc/my.cnf.d