Ansible: Include variables file under role/xyzrole/main.yml

I have some variables that dont change and some that do from time to time. I'd like my main.yml within the role to list all the static variables, for the dynamic variables I'd like to put them in a different file and just include the new file everytime there is a change.

Like this:

main.yml:

---
var1: somevalue
var2: anothervalue
var3:
  var3.1: somevalue that changes
  var3.2: anothervalue that changes

Instead of that, I'd like to do the following:

main.yml:

---
var1: somevalue
var2: anothervalue
invlude_vars: varsfile.yml

varsfile.yml:

---
var3:
  var3.1: somevalue that changes
  var3.2: anothervalue that changes

This way I dont have to touch main.yml but change varsfile.yml everytime there is any change. I tried it, ends in following error:

fatal: [hostnamehidden]: FAILED! => {"msg": "The task includes an option with an undefined variable. The error was: 'var3.1' is undefined\n\nThe error appears to be in '.../tasks/main.yml': line 7, column 3, but may\nbe elsewhere in the file depending on the exact syntax problem.\n\nThe offending line appears to be:\n\n\n- name: Some tasks is getting executed here^ here\n"}

Any ideas? Is it possible to do this at all within the roles/rolename/vars/main.yml?

Solution

There are many options depending on the exact use-case. For example, use the default values. Given the role

shell> cat roles/role3/defaults/main.yml 
var1: somevalue
var2: anothervalue
var3:
  var3.1: "{{ somevalue_that_changes|default('UNDEFINED') }}"
  var3.2: "{{ anothervalue_that_changes|default('UNDEFINED') }}"

shell> cat roles/role3/tasks/main.yml 
- debug:
    var: var3

The playbook

shell> cat playbook.yml
- hosts: localhost
  roles:
    - role3

gives

shell> ansible-playbook playbook.yml

TASK [role3 : debug] ****
ok: [localhost] => 
  var3:
    var3.1: UNDEFINED
    var3.2: UNDEFINED

If you define the variable, for example on the command-line, the playbook gives

shell> ansible-playbook playbook.yml -e somevalue_that_changes=XYZ

TASK [role3 : debug] ****
ok: [localhost] => 
  var3:
    var3.1: XYZ
    var3.2: UNDEFINED

Of course, it's possible to put the variables into a file and use the file in the playbook. For example

shell> cat varsfile.yml 
somevalue_that_changes: XYZ
anothervalue_that_changes: 123

shell> cat playbook.yml
- hosts: localhost
  vars_files:
    - varsfile.yml
  roles:
    - role3

gives

shell> ansible-playbook playbook.yml

TASK [role3 : debug] ****
ok: [localhost] => 
  var3:
    var3.1: XYZ
    var3.2: '123'

It's possible to include the data in the role instead of the playbook. For example

shell> cat roles/role3/tasks/main.yml
- include_vars: varsfile.yml
- debug:
    var: var3

gives

shell> ansible-playbook playbook.yml

TASK [role3 : debug] ****
ok: [localhost] => 
  var3:
    var3.1: XYZ
    var3.2: '123'

Q: "Separate the changing variables into another file and include them within vars/main.yml"

A: Use lookup plugin file. For example, put the changing variables into the file

shell> cat files/varsfile.yml
var3.1: XYZ
var3.2: 123

Combine the changing variables from the file with the defaults

shell> cat roles/role3/defaults/main.yml 
var1: somevalue
var2: anothervalue
var3_default:
  var3.1: "{{ somevalue_that_changes|default('UNDEFINED') }}"
  var3.2: "{{ anothervalue_that_changes|default('UNDEFINED') }}"

shell> cat roles/role3/vars/main.yml
var3: "{{ var3_default|combine(lookup('file', 'varsfile.yml')|from_yaml) }}"

Then, the debug task

shell> cat roles/role3/tasks/main.yml
- debug:
    var: var3

gives

  var3:
    var3.1: XYZ
    var3.2: 123

It's rather flexible. For example, if you omit var3.1

shell> cat files/varsfile.yml
var3.2: 123

The result is

  var3:
    var3.1: UNDEFINED
    var3.2: 123

In addition to this, you can still override the default values. For example,

shell> ansible-playbook playbook.yml -e somevalue_that_changes=ABC

gives

  var3:
    var3.1: ABC
    var3.2: 123

Fit the defaults/vars, paths, and combinations to your needs.