In ansible how do I concatenate a already defined variable in a settings file yaml and an extra-var? - variables

Question

I created a settings file called settings.yaml that looks like this:
cust_int: 'ens224'
cust_sub_int: '{{ cust_int }}.{{ cust }}
cust_int, is the already defined variable above
cust, Is a variable provided with --extra-var
here is the playbook:
- name: Include vars
include_vars:
file: ../../../settings.yaml
name: settings
- debug: msg="{{ settings.cust_sub_int }}"
When trying to concatenate this way I get unclear error that the playbook "did not find the expected key".
My question is, how can I combine these two variables in my settings file? I dont want to have to use set_fact in all my playbooks.

Answer 1

See ansible cannot use variable to learn details why this is not working. The solution is rather simple. Split the settings into common variables and the dictionary. For example,
shell> cat settings-common.yaml
_cust_int: 'ens224'
shell> cat settings.yaml
cust_int: '{{ _cust_int }}'
cust_sub_int: '{{ _cust_int }}.{{ cust }}'
Include both files
- include_vars:
file: settings-common.yaml
- include_vars:
file: settings.yaml
name: settings
Running the play with extra var cust=foo gives the expected result
settings:
cust_int: ens224
cust_sub_int: ens224.foo
Example of a complete project for testing
shell> tree .
.
├── ansible.cfg
├── hosts
├── pb.yml
├── settings-common.yaml
└── settings.yaml
0 directories, 5 files
shell> cat ansible.cfg
[defaults]
gathering = explicit
inventory = $PWD/hosts
retry_files_enabled = false
stdout_callback = yaml
shell> cat hosts
localhost
shell> cat pb.yml
- hosts: localhost
tasks:
- include_vars:
file: settings-common.yaml
- include_vars:
file: settings.yaml
name: settings
- debug:
var: settings
- debug:
msg: "{{ settings.cust_sub_int }}"
gives
shell> ansible-playbook pb.yml -e cust=foo
PLAY [localhost] *****************************************************************************************************************
TASK [include_vars] **************************************************************************************************************
ok: [localhost]
TASK [include_vars] **************************************************************************************************************
ok: [localhost]
TASK [debug] *********************************************************************************************************************
ok: [localhost] =>
settings:
cust_int: ens224
cust_sub_int: ens224.foo
TASK [debug] *********************************************************************************************************************
ok: [localhost] =>
msg: ens224.foo
PLAY RECAP ***********************************************************************************************************************
localhost: ok=4 changed=0 unreachable=0 failed=0 skipped=0 rescued=0 ignored=0