Ansible: Up and Running, 2nd Edition

Chapter 4. Variables and Facts

Ansible is not a full-fledged programming language, but it does have several programming language features, and one of the most important of these is variable substitution. This chapter presents Ansible’s support for variables in more detail, including a certain type of variable that Ansible calls a fact.

Defining Variables in Playbooks

The simplest way to define variables is to put a vars section in your playbook with the names and values of variables. Recall from Example 2-8 that we used this approach to define several configuration-related variables, like this:

vars:
  key_file: /etc/nginx/ssl/nginx.key
  cert_file: /etc/nginx/ssl/nginx.crt
  conf_file: /etc/nginx/sites-available/default
  server_name: localhost

Ansible also allows you to put variables into one or more files, using a section called vars_files. Let’s say we want to take the preceding example and put the variables in a file named nginx.yml instead of putting them right in the playbook. We would replace the vars section with a vars_files that looks like this:

vars_files:
 - nginx.yml

The nginx.yml file would look like Example 4-1.

Example 4-1. nginx.yml

key_file: /etc/nginx/ssl/nginx.key
cert_file: /etc/nginx/ssl/nginx.crt
conf_file: /etc/nginx/sites-available/default
server_name: localhost

You’ll see an example of vars_files in action in Chapter 6 when we use it to separate out the variables that contain sensitive information.

As we discussed in Chapter 3, Ansible also lets you define ...