Ansible : Select inventory file out of multiple hosts.ini for three environments based on the version passed as a variable

Question

I have a task , in which I need to select the target environment/hosts amongst the multiple inventory files placed in different folders under inventories/ directory. The selection is based on the version passed as a variable.

inventories/
           preprod/
                  group_vars/
                  hosts.ini
                  ...
           systest/
                  group_vars/
                  hosts.ini
                  ...
           uat/
                  group_vars/
                  hosts.ini
                  ...

So if the version varaiable is 1.x.x then the hosts.ini under preprod should be selected, if its 2.x.x then the hosts.ini under systest should be selected and if its 3.x.x the hosts.ini under uat should be selected.

---
- name: Select hosts from multiple inventories based on version passed as a variable
  hosts: all
  vars:
    version: '1.0'
  tasks:
  - name: Get hosts from first inventory
    set_fact:
      hosts_1: "{{ groups['inventory_1'] | selectattr('version', 'equalto', version) | map(attribute='hostname') | list }}"
  - name: Get hosts from second inventory
    set_fact:
      hosts_2: "{{ groups['inventory_2'] | selectattr('version', 'equalto', version) | map(attribute='hostname') | list }}"
  - name: Merge hosts from both inventories
    set_fact:
      hosts: "{{ hosts_1 + hosts_2 }}"
  - name: Run tasks with hosts
    debug:
      msg: "{{ item }}"
    loop: "{{ hosts }}"

Vladimir Botka · Answer 1 · 2023-02-10T20:43:48.273

Short answer: Copy the inventory file in the first play, refresh_inventory, and use it in the second play. Unfortunately, this does not refresh group_vars from the directories. As a workaround put the group_vars into the inventory files.

Details: Given the project for testing

shell> tree .
.
├── ansible.cfg
├── hosts.env
├── inventory
│   ├── preprod
│   │   └── hosts.ini
│   ├── systest
│   │   └── hosts.ini
│   └── uat
│       └── hosts.ini
└── pb.yml

4 directories, 6 files

Put the group_vars into the inventory files

shell> cat inventory/preprod/hosts.ini 
[all]
preprod1
preprod2
preprod3

[all:vars]
env_gv=preprod

shell> cat inventory/systest/hosts.ini 
systest1
systest2
systest3

[all:vars]
env_gv=systest

shell> cat inventory/uat/hosts.ini 
[all]
uat1
uat2
uat3

[all:vars]
env_gv=uat

The playbook

shell> cat pb.yml
- hosts: localhost
  vars:
    envs:
      1: preprod
      2: systest
      3: uat
    env: "{{ envs[version.split('.').0|int] }}"
  tasks:
    - debug:
        msg: "Use environment: {{ env }}"
    - copy:
        src: "{{ playbook_dir }}/inventory/{{ env }}/hosts.ini"
        dest: "{{ playbook_dir }}/hosts.env"
    - meta: refresh_inventory

- hosts: all
  tasks:
    - block:
        - debug:
            var: ansible_play_hosts_all
        - debug:
            var: env_gv
      run_once: true

gives

^{version=1.0 works in the environment preprod
shell> ansible-playbook -i hosts.env -e version=1.0 pb.yml

PLAY [localhost] ****************************************************************************************

TASK [debug] ********************************************************************************************
ok: [localhost] =>
msg: 'Use environment: preprod'

TASK [copy] *********************************************************************************************
changed: [localhost]

TASK [meta] *********************************************************************************************

PLAY [all] **********************************************************************************************

TASK [debug] ********************************************************************************************
ok: [preprod1] =>
ansible_play_hosts_all:
- preprod1
- preprod2
- preprod3

TASK [debug] ********************************************************************************************
ok: [preprod1] =>
env_gv: preprod

PLAY RECAP **********************************************************************************************
localhost: ok=2 changed=1 unreachable=0 failed=0 skipped=0 rescued=0 ignored=0
preprod1: ok=2 changed=0 unreachable=0 failed=0 skipped=0 rescued=0 ignored=0

version=2.0 works in the environment systest
shell> ansible-playbook -i hosts.env -e version=2.0 pb.yml

PLAY [localhost] ****************************************************************************************

TASK [debug] ********************************************************************************************
ok: [localhost] =>
msg: 'Use environment: systest'

TASK [copy] *********************************************************************************************
changed: [localhost]

TASK [meta] *********************************************************************************************

PLAY [all] **********************************************************************************************

TASK [debug] ********************************************************************************************
ok: [systest1] =>
ansible_play_hosts_all:
- systest1
- systest2
- systest3

TASK [debug] ********************************************************************************************
ok: [systest1] =>
env_gv: systest

PLAY RECAP **********************************************************************************************
localhost: ok=2 changed=1 unreachable=0 failed=0 skipped=0 rescued=0 ignored=0
systest1: ok=2 changed=0 unreachable=0 failed=0 skipped=0 rescued=0 ignored=0

version=3.0 works in the environment uat
shell> ansible-playbook -i hosts.env -e version=3.0 pb.yml

PLAY [localhost] ****************************************************************************************

TASK [debug] ********************************************************************************************
ok: [localhost] =>
msg: 'Use environment: uat'

TASK [copy] *********************************************************************************************
changed: [localhost]

TASK [meta] *********************************************************************************************

PLAY [all] **********************************************************************************************

TASK [debug] ********************************************************************************************
ok: [uat1] =>
ansible_play_hosts_all:
- uat1
- uat2
- uat3

TASK [debug] ********************************************************************************************
ok: [uat1] =>
env_gv: uat

PLAY RECAP **********************************************************************************************
localhost: ok=2 changed=1 unreachable=0 failed=0 skipped=0 rescued=0 ignored=0
uat1: ok=2 changed=0 unreachable=0 failed=0 skipped=0 rescued=0 ignored=0

Example. Precedence of group_vars. YAML format.
shell> tree .
.
├── ansible.cfg
├── group_vars
│   └── all.yml
├── hosts
├── inventories
│   ├── preprod
│   │   └── hosts
│   ├── systest
│   │   └── hosts
│   └── uat
│   └── hosts
├── inventory
│   ├── group_vars
│   │   └── all.yml
│   └── hosts
└── pb.yml

7 directories, 9 files

shell> cat group_vars/all.yml
env_gv3: playbook group_vars/all

shell> cat inventory/group_vars/all.yml
env_gv2: inventory group_vars/all

shell> cat inventories/preprod/hosts
all:
hosts:
preprod1:
preprod2:
preprod3:
vars:
env_gv1: preprod1 inventory file group_vars
env_gv2: preprod2 inventory file group_vars
env_gv3: preprod3 inventory file group_vars

shell> cat inventories/systest/hosts
all:
hosts:
systest1:
systest2:
systest3:
vars:
env_gv1: systest1 inventory file group_vars
env_gv2: systest2 inventory file group_vars
env_gv3: systest3 inventory file group_vars

shell> cat inventories/uat/hosts
all:
hosts:
uat1:
uat2:
uat3:
vars:
env_gv1: uat1 inventory file group_vars
env_gv2: uat2 inventory file group_vars
env_gv3: uat3 inventory file group_vars

shell> cat pb.yml
- hosts: localhost
vars:
envs:
1: preprod
2: systest
3: uat
env: "{{ envs[version.split('.').0|int] }}"
tasks:
- debug:
msg: "Use environment: {{ env }}"
- copy:
src: "{{ playbook_dir }}/inventories/{{ env }}/hosts"
dest: "{{ playbook_dir }}/inventory/hosts"
- meta: refresh_inventory

- hosts: all
tasks:
- block:
- debug:
var: ansible_play_hosts_all
- debug:
msg: |
env_gv1: {{ env_gv1 }}
env_gv2: {{ env_gv2 }}
env_gv3: {{ env_gv3 }}
run_once: true

shell> ansible-playbook -i inventory/hosts -e version=2.0 pb.yml

shows that variable precedence:

inventory file or script group vars
inventory group_vars/all
playbook group_vars/all

works as expected
PLAY [localhost] ****************************************************************************************

TASK [debug] ********************************************************************************************
ok: [localhost] =>
msg: 'Use environment: systest'

TASK [copy] *********************************************************************************************
changed: [localhost]

TASK [meta] *********************************************************************************************

PLAY [all] **********************************************************************************************

TASK [debug] ********************************************************************************************
ok: [systest1] =>
ansible_play_hosts_all:
- systest1
- systest2
- systest3

TASK [debug] ********************************************************************************************
ok: [systest1] =>
msg: |-
env_gv1: systest1 inventory file group_vars
env_gv2: inventory group_vars/all
env_gv3: playbook group_vars/all

PLAY RECAP **********************************************************************************************
localhost: ok=2 changed=1 unreachable=0 failed=0 skipped=0 rescued=0 ignored=0
systest1: ok=2 changed=0 unreachable=0 failed=0 skipped=0 rescued=0 ignored=0}

Just to be Sure, We have multiple yml files inside the group_vars , So we can include contents of each file inside the host.ini file under different groups without affecting the results. Please correct me if I am wrong. — Rahul Singh, Feb 10 '23 at 17:53
Yes. This should work. What's inside the file *host.ini* ( or inside the file *hosts.env* in the above example) will be refreshed by *`meta: refresh_inventory`*. You might want to change the format to *host.yaml*. It's easier to declare the variables in YAML. — Vladimir Botka, Feb 10 '23 at 19:01

Ansible : Select inventory file out of multiple hosts.ini for three environments based on the version passed as a variable

1 Answers1