Ansible Inventory

A unified plaintext store (inventory.txt) of all of our hosts that are managed with Ansible. Supposed to be integrated into the relevant Ansible repos as a git submodule.

How it works

It is simple. The Python script generate_inventory reads the lines from inventory.txt and constructs a well-defined Ansible inventory file for all our hosts from it. This is handy because it allows for a more streamlined adding, removing and changing of hosts and the groups that they are in.

Adding a host

inventory.txt has the following structure. To add a new host, simply add a new line starting with - followed by a space, then the hostname and then the applicable groups in square brackets.

To illustrate, generate_inventory` would take the input below:

# some comment
- example.fsfe.org [group1, group2, group3, group4]
- example2.fsfe.org [group1, group5]

and would then return the following as standard output:

{
  "group1": {
    "hosts": [
      "example.fsfeurope.org",
      "example2.fsfeurope.org",
    ]
  },
  "group2": {
    "hosts": [
      "example.fsfeurope.org",
    ]
  },
  "group3": {
    "hosts": [
      "example.fsfeurope.org",
    ]
  },
  "group4": {
    "hosts": [
      "example.fsfeurope.org",
    ]
  },
  "group5": {
    "hosts": [
      "example2.fsfeurope.org",
    ]
  }
}

Possible future improvements

• Make script more robust to, for example, allow for comments in inventory.txt
• Create CLI to remove, update and add hosts and groups
• Add the ability to store some host_vars should the need arise (Currently, we do this in the repos where the playbooks are)

Resources

• Anisble Docs on working with inventories (https://docs.ansible.com/ansible/latest/user_guide/intro_inventory.html)
• Ansible Docs on working with dynamic inventories (https://docs.ansible.com/ansible/latest/user_guide/intro_dynamic_inventory.html)
  • the above links to repo containing a number of dynamic inventory generation scripts including one for ProxMox (https://github.com/ansible-collections/community.general/blob/main/scripts/inventory/proxmox.py)