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Ansible: More about the Inventory File

Ansible default inventory is located at /etc/ansible/hosts. But we can have it elsewhere. For example at /home/me/ansible/hosts.ini. Then point ansible to it using the -i flag.

ansible web -m ping -i ./hosts.ini

Or I can just confirgure ansible.cfg to point to the path of my inventory file.

[defaults]

inventory = /etc/ansible/inventory/hosts.ini

Hosts can be organized in groups inside the inventory file. A group name must be unique and following the criteria of a valid variable name.

Here are example of groups: web and db

[web]
192.168.10.15
192.168.10.16

[db]
192.168.12.15
192.168.12.16
192.168.12.17

Here is the same inventory in YAML format

web:
  hosts:
    192.168.10.15:
    192.168.10.16:
db:
  hosts:
    192.168.12.15:
    192.168.12.16:
    192.168.12.17:

Ansible automatically creates the all and ungrouped groups behind the scene. The all group contains all hosts, and ungrouped group contains all that are not in any group.

So, ansible -m ping all will all hosts listed in the inventory file, and ansible -m ping ungrouped will ping all hosts not listed in any group.

Do more in your inventory

  • A host can be part of multiple groups

  • Groups can also be grouped

prod:
  children:
    web:
    db:
test:
  children:
    web_test:

[prod:children]
web
db

[test:children]
web_test
  • Add a range of hosts
[servers]
192.168.11.[15:35]

servers:
  hosts:
    192.168.11.[15:35]:
  • Add variables to hosts or groups
[prod]
192.168.10.15:4422

prod1 ansible_port=4422 ansible_host=192.168.10.22

You can do way more than what I have listed above, I am not going to bore with everything about Ansible inventory here because I don't need to use them at this stage of my learning. But if you feel like you want to learn more about this topic, go here

Good bye for now