Variables

Ansible variables can be defined directly in the inventory file. This is useful for defining variables that are common to all hosts in a group. For example, you can define a variable called ansible_user to specify the user to use when connecting to the hosts in a group.

If you have a lot of variables you can write them into a separate file and include it in the inventory file. This is useful for keeping the inventory file clean and readable.

Attention

Variables will always be rendered directly to the hosts before you run a playbook. This means that ansible itself has no global variables that can be modified for all hosts at runtime. In the advanced section you will learn how to make variables usable across different hosts.

Defining variables in the inventory file

You can define variables globally, for a group or for a host. The variable defined closest to the host will always take precedence.

inventory.yml

all:
  hosts:
    webserver1:
        web_color: "green"
    webserver2:
    webserver3:
  vars:
    web_color: "orange"
  children:
    webserver:
      vars:
        web_color: "blue"
      hosts:
        webserver2:

Defining variables in a separate file

You can define variables in separate files. This is useful for keeping the inventory file clean and readable. The folders group_vars and host_vars in your working directory can be used to assign variables per host or group.

Host variable filesGroup variable files

host_vars/server1.ymlhost_vars/localhost.yml

my_var_for_server1: "Hello World"

my_var_for_localhost: "Hello World"

group_vars/webserver.ymlgroup_vars/all.yml

my_var_for_all_webservers: "Hello World"

my_var_for_all_hosts: "Hello World"

Magic Variables

Magic variables are variables that are automatically set by Ansible, they are not set in your inventory file. These variables are very important because they are used a lot in ansible playbooks and roles.

Some good examples for magic variables are:

Variable	Content
`hostvars`	A dictionary/map with all the hosts in inventory and variables assigned to them
`group_names`	List of groups the current host is part of
`groups`	A dictionary/map with all the groups in inventory and each group has the list of hosts that belong to it
`inventory_hostname`	The inventory name for the ‘current’ host being iterated over in the play

Ansible Reference: https://docs.ansible.com/ansible/latest/reference_appendices/special_variables.html#magic-variables