Ansible Jinj2 templates
Jinja templating helps to standartize and to template files such as config and system roles. Here is basic syntax.
Using template module:
- name: Deploy hello.html
template:
src: templates/hello.html.j2
dest: /var/www/html/hello.html
$ cat vars/all/all.yml
print_msg = "This file is managed by Ansible"
$ cat templates/hello.html.j2
{{ print_msg }}
The system kernel is: {{ ansible_hostname }}
\'{% EXPR %}'- for expressions or logic.\'{{ EXPR }}'- outputs results of expressions or variables\'{# COMMENT #}'- comments
We can manage a jinja file using loops and conditions.
Using Loops
{# Check list with the models of auto #}
{% for model in models if not model == "BMW" %}
Line {{ loop.index }} - {{ model }}
{% endfor %}
Or let’s print all defined hostnames
{% for server_name in groups['servers'] %}
{{ server_name }}
{% endfor %}
Or classic task, define /etc/hosts file:
{% for host in groups['all'] %}
{{ hostvars[host]['ansible_facts']['default_ipv4']['address'] }} {{ hostvars[host]['ansible_facts']['fqdn'] }} {{ hostvars[host]['ansible_facts']['hostname'] }}
{% endfor %}
Using condition:
{% if finished %}
{{ print_me }}
{% endif %}
Additionally, in jinja template we can apply some filters to express the output to yaml or json or to get expression from yaml and json. These filters are: to_json, to_yaml, to_nice_yaml, to_nice_json, from_json, from_yaml.