How does Ansible's Jinja2 templating work in playbooks?

Jinja2 is the templating engine Ansible uses to evaluate expressions like {{ variable }}, conditionals, and loops, both directly inside playbook YAML values and inside .j2 template files processed by the template module.

# Inline in a playbook
- name: Show a computed value
  ansible.builtin.debug:
    msg: "{{ ansible_facts['memtotal_mb'] // 1024 }} GB of RAM"

# Inside a .j2 template file
server_name {{ inventory_hostname }};
{% if enable_ssl %}
listen 443 ssl;
{% endif %}

Inside {{ }} expressions, Ansible supports the full range of Jinja2 features: arithmetic, string manipulation, and filters (like {{ my_list | length }} or {{ name | upper }}) that transform a value inline. Template files use the block-style {% %} syntax for control flow such as if/else and for loops, letting a single template generate different output per host based on that host's variables and facts, which is what makes the template module powerful for generating per-host configuration files from one shared source file.

Invest now in Acorns!!! 🚀
Join Acorns and get your $5 bonus!

Acorns is a micro-investing app that automatically invests your "spare change" from daily purchases into diversified, expert-built portfolios of ETFs. It is designed for beginners, allowing you to start investing with as little as $5. The service automates saving and investing. Disclosure: I may receive a referral bonus.

Invest now!!! Get Free equity stock (US, UK only)!

Use Robinhood app to invest in stocks. It is safe and secure. Use the Referral link to claim your free stock when you sign up!.

The Robinhood app makes it easy to trade stocks, crypto and more.

Webull! Receive free stock by signing up using the link: Webull signup.