This is a dynamic alternative to Ansible static inventory file
Instead of writing a static hosts file with groups and hosts, it simply reads the YAML files in host_vars/*.yml and creates a dynamic inventory based on them.
The dynamic inventory script is called inventory in this example and simply by running it you should get some json output:
~/ansible-inventory (master) $ ./inventory.py | python -m json.tool
{
"databases": {
"hosts": [
"db1.example.com"
]
},
"dc_atlanta": {
"hosts": [
"db1.example.com",
"web1.example.com",
"worker4.example.com"
]
},
"dc_london": {
"hosts": [
"web2.example.com"
]
},
"webservers": {
"hosts": [
"web1.example.com",
"web2.example.com"
]
},
"workers": {
"hosts": [
"worker4.example.com"
]
}
}
You also need to set the inventory script in ansible.cfg:
~/ansible-inventory (master) $ cat ansible.cfg
[defaults]
inventory = ./inventory
And you are good to go. When running ansible and ansible-playbook it will read the output from the dynamic inventory. Adding/removing a host is as simple as adding/removing a file in host_vars/. Just make sure that host_fqdn and host_groups is set.