Ansible variable precedence

Source: http://docs.ansible.com/ansible/latest/playbooks_variables.html#variable-precedence-where-should-i-put-a-variable

From least to most important

• command line values (for example, -u my_user, these are not variables)
• role defaults (defined in role/defaults/main.yml)
• inventory file or script group vars
• inventory group_vars/all