Inventories and Configuration

Updated Dec 04, 2020 ·

Overview

An inventory tells Ansible which hosts it can manage. The configuration file controls defaults such as inventory location, remote user, roles path, and host key checking.

Static Inventory

A simple inventory can group hosts by purpose.

[webservers]
tstsvr1
tstsvr2
tstsvr3
tstsvr4

[loadbalancers]
lb1

[local]
localhost ansible_connection=local

You can also define aliases with ansible_host.

[webservers]
app1 ansible_host=13.251.146.254
app2 ansible_host=122.248.203.239

Inventory Groups

Groups help target related hosts.

ansible webservers --list-hosts
ansible loadbalancers --list-hosts
ansible all --list-hosts

Nested groups use :children.

[prod:children]
webservers
loadbalancers

Inventory Variables

Inventory variables can be set beside a host, inside a group, or in host_vars and group_vars.

Location	Use case
Host line	Small host-specific connection details.
Group section	Shared values for every host in the group.
host_vars	Larger host-specific variables.
group_vars	Larger group-specific variables.

Ansible Configuration

Ansible looks for configuration in this order:

1. ANSIBLE_CONFIG
2. ansible.cfg in the current directory
3. .ansible.cfg in the home directory
4. /etc/ansible/ansible.cfg

Example project configuration:

[defaults]
inventory = inventories/edendev.inv
remote_user = eden
roles_path = roles
host_key_checking = False

Check active changes.

ansible-config dump --only-changed

SSH Trust

The controller needs SSH access to managed nodes.

ssh-keygen
ssh-copy-id tstsvr1
ssh-copy-id tstsvr2
ssh-copy-id tstsvr3
ssh-copy-id tstsvr4

warning

Do not commit private SSH keys, real host credentials, or vault password files into the repository.