Is it possible to wildcard a host_vars directory?

Question

Long story short: I've established a home-lab where I use Ansible with VMware dynamic inventory plugin. To distinguish between the different VMs the plugin adds the uid to the hostname, example: unique-test-vm_2612e560x1284x8457e115. This makes it hard for me to create host_vars directories because I constantly have to run ansible-inventory -i ... and copy the inventory name.

Question
Is it possible to create "wildcarded" host_vars directories without including the uid in the directory name? Meaning the name of the directory would be unique-test-vm instead of unique-test-vm_2612e560x1284x8457e115.

Answer 1

It's not possible to create "wildcard" host_vars. But, this use-case can be solved either by include_vars or by group_vars. Mind the precedence of the variables. See Variable precedence: Where should I put a variable?.

---

include_vars (single host)

For example, let's have this inventory

shell> cat hosts
testX-vm_07

Let's create host_vars

shell> cat host_vars/testX-vm/main.yml 
test_var: test var for hosts testX-vm_*

Then the playbook below reads the variables from the directory host_vars/testX-vm. Fit the parsing of the inventory_hostname to your needs

shell> cat pb.yml
- hosts: testX-vm_07
  tasks:
    - include_vars:
        dir: "{{ 'host_vars/' ~ my_vars_dir }}"
      vars:
        my_vars_dir: "{{ inventory_hostname.split('_').0 }}"
    - debug:
        var: test_var

gives

shell> ansible-playbook -i hosts pb.yml

PLAY [testX-vm_07] ****

TASK [include_vars] ****
ok: [testX-vm_07]

TASK [debug] ****
ok: [testX-vm_07] => 
  test_var: test var for hosts testX-vm_*

---

group_vars (multiple hosts)

For example, let's have this inventory

shell> cat hosts
testX-vm_01
testX-vm_02
testX-vm_03
testY-vm_01
testY-vm_02
testY-vm_03

Let's create group_vars that shall be shared by the hosts testX-vm_* and testY-vm_* respectively

shell> cat group_vars/testX_vm/main.yml
test_var: test var for testX_vm group

shell> cat group_vars/testY_vm/main.yml
test_var: test var for testY_vm group

Then the playbook below creates groups testX_vm and testY_vm in the first play and uses the groups in the second and third play. For example,

shell> cat pb.yml
- hosts: all
  gather_facts: false
  tasks:
    - block:
        - add_host:
            name: "{{ item }}"
            groups: testX_vm
          loop: "{{ ansible_play_hosts_all|
                    select('match', '^testX-vm_(.*)$')|
                    list }}"
        - add_host:
            name: "{{ item }}"
            groups: testY_vm
          loop: "{{ ansible_play_hosts_all|
                    select('match', '^testY-vm_(.*)$')|
                    list }}"
      run_once: true
  
- hosts: testX_vm
  tasks:
    - debug:
        var: test_var

- hosts: testY_vm
  tasks:
    - debug:
        var: test_var

gives

shell> ansible-playbook -i hosts pb.yml 

PLAY [all] ****
TASK [add_host] ****
changed: [testX-vm_01] => (item=testX-vm_01)
changed: [testX-vm_01] => (item=testX-vm_02)
changed: [testX-vm_01] => (item=testX-vm_03)

TASK [add_host] ****
changed: [testX-vm_01] => (item=testY-vm_01)
changed: [testX-vm_01] => (item=testY-vm_02)
changed: [testX-vm_01] => (item=testY-vm_03)

PLAY [testX_vm] ****
ok: [testX-vm_01] => 
  test_var: test var for testX_vm group
ok: [testX-vm_02] => 
  test_var: test var for testX_vm group
ok: [testX-vm_03] => 
  test_var: test var for testX_vm group

PLAY [testY_vm] ****
ok: [testY-vm_01] => 
  test_var: test var for testY_vm group
ok: [testY-vm_02] => 
  test_var: test var for testY_vm group
ok: [testY-vm_03] => 
  test_var: test var for testY_vm group