Templates

Ansible uses the Jinja2 templating system for template files. Again, this is nice because you should be used to this from the FastAPI walk-through!

Variables and logic expressions are placed between tags, or delimiters.

Jinja2 templates use {% EXPR %} for expressions or logic.

{{ EXPR }} are used for outputting the results of an expression or a variable.

A Jinja2 template is composed of multiple elements: data, variables, and expressions.

Example:

# {{ ansible_managed }}
# DO NOT MAKE LOCAL MODIFICATIONS TO THIS FILE AS THEY WILL BE LOST

Port {{ ssh_port }}
ListenAddress {{ ansible_facts['default_ipv4']['address'] }}

A Jinja2 template for a configuration file can be deployed to the managed hosts using the template module.

Example:

- name: render template
  template:
    src: /tmp/j2-template.j2
    dest: /tmp/dest-config-file.txt

Use the “Ansible managed” string set in the ansible_managed directive.

Example:

ansible.cfg file:

ansible_managed = Ansible managed

Include the ansible_managed string inside a Jinja2 template:

{{ ansible_managed }}

Using Loops

Jinja2 uses the for statement to provide looping functionality.

{% for user in users %}
      {{ user }}
{% endfor %}

Using Conditionals

Jinja2 uses the if statement to provide conditional control.

Example:

{% if finished %}
{{ result }}
{% endif %}

Variable Filters

The to_json filter formats the expression output using JSON, and the to_yaml filter formats the expression output using YAML.

{{ output | to_json }}
{{ output | to_yaml }}
{{ output | to_nice_json }}
{{ output | to_nice_yaml }}

Variable Tests

Built-in Ansible tests used to test return values include failed, changed,succeeded, and skipped.