Get a variable value from another variable

[chemi0213]

The example playbook is below:

$ cat test.yml
- hosts: localhost
  gather_facts: false
  tasks:
  - name: print
    debug:
      msg: "{{ policy }}"
    vars:
      name: checkpolicy_1
      policy: "{{ checkpolicy_1 | default('Policy_A') }}"

Goal:
When user specify checkpolicy_1 via --extra-var. the value of the variable "policy" will be "Policy_B". If not specify, will be "Policy_A"

However the number of checkpolicy might be a lot and vary, I want to write something like below, and achieve the same result:

$ cat test.yml
- hosts: localhost
  gather_facts: false
  tasks:
  - name: print
    debug:
      msg: "{{ policy }}"
    vars:
      name: checkpolicy_1
      policy: "{{ vars['name'] | default('Policy_A') }}"

Is it possible to do that?

[maple52046]

vars is a Python dictionary, so you can use setdefault method to get data from vars with a default value.

E.g.:

- hosts: localhost
  vars:
    default_policy: "policy_a"

  tasks:
  - name: test
    debug:
      msg: "{{ vars.setdefault('checkpolicy_1', default_policy) }}"

  - name: set var
    set_fact:
      policy: "{{ vars.setdefault('checkpolicy_1', default_policy) }}"

  - name: test again
    debug:
      msg: "{{ policy }}"

However, setdefault didn't update vars in Ansible. So, I use set_fact to store the data into a new variable.