Overview of ansible jinja2 template

ansible allows conditional judgment and loops in jinja2 templates, but not in playbook

ansible jinja2 template usage

Basic grammar

{{EXPR}} outputs variable values, which output custom variable values or facts
 1)playbook file uses template module
 2) Variables in template files use {name}, such as {PORT} or facts

jinja2 Template Logic Judgment

#Loop expression
{% for i in EXPR %}
{% endfor %}

#Conditional judgement
{% if EXPR %}
{% elif EXPR %}
{% else %}
{% ednif %}

#Notes
{# COMMENT #}

jinja2 example

• Edit playbook

[root@m01 ~]# vim jinja2.yml
- hosts: web_group
  tasks:
    - name: Copy Template File
      template:
        src: ./motd.j2
        dest: /etc/motd

• Prepare motd.j2

[root@m01 ~]# vim motd.j2
Welcome to {{ ansible_fqdn }}
This system total mem is : {{ ansible_memtotal_mb }} MB
This system free mem is: {{ ansible_memfree_mb }} MB

• Execute playbook

ansible jinja2 manages nginx

Push files using playbook

1. Edit playbook

[root@m01 ~]# vim lb.yml
- hosts: lb_group
  vars:
    http_port: 80
    server_name: www.drz.com
  tasks:
    - name: copy
      template:
        src: ./www.drz.com.conf.j2
        dest: /etc/nginx/conf.d/www.drz.com.conf
      notify: reload nginx
  handlers:
    - name: reload nginx
      systemd:
        name: nginx
        state: reloaded

2. Preparing configuration files

[root@m01 ~]# vim lb.yml
- hosts: lb_group
  vars:
    http_port: 80
    server_name: www.drz.com
  tasks:
    - name: copy
      template:
        src: ./www.drz.com.conf.j2
        dest: /etc/nginx/conf.d/www.drz.com.conf
      notify: reload nginx
  handlers:
    - name: reload nginx
      systemd:
        name: nginx
        state: reloaded

ansible jinja2 management keepalived

Keeping alived original match

#keepalived master configuration file
global_defs {
    router_id lb01
}

vrrp_instance VI_1 {
    state MASTER
    interface eth0
    virtual_router_id 50
    priority 150
    advert_int 1
    authentication {
        auth_type PASS
        auth_pass 1111
    }
    virtual_ipaddress {         
        10.0.0.3
    }
}


#keepalived backup configuration file
global_defs {
    router_id lb02
}

vrrp_instance VI_1 {
    state BACKUP        
    interface eth0
    virtual_router_id 50
    priority 100
    advert_int 1
    authentication {    
        auth_type PASS
        auth_pass 1111
    }
    virtual_ipaddress {
        10.0.0.3
    }
}

Push the keepalived configuration file

[root@m01 ~]# vim keepalived.yml
- hosts: lb_group
  tasks:
    - name: copy file
      template:
        src: ./keepalived.j2
        dest: /etc/keepalived/keepalived.conf
      notify: restart keepalived

  handlers:
    - name: restart keepalived
      systemd:
        name: keepalived
        state: restarted

Prepare the keepalived configuration file

[root@m01 ~]# vim keepalived.j2
global_defs {
    router_id {{ ansible_fqdn }}
}

vrrp_instance VI_1 {
{% if ansible_fqdn == "lb01" %}
    state MASTER
    priority 150
{% else %}
    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
    }
}