- name: set location zone facts
  set_fact:
    fact_zone: "['facter_ec2_metadata']['placement']['availability-zone']"

- name: quotes
  debug:
    msg: "{{ ['fact_zone'] }}"

- name: set label zone nodes
  shell: oc label node {{ item }} zone="{{ hostvars[item]['fact_zone'] }}"
  with_items: "{{ groups['nodes']|unique }}"


### I want the literal string to access to the hostvar[<item>]['facter_ec2_metadata']['placement']['availability-zone']
### I get the following hostvar[<item>]"['facter_ec2_metadata']['placement']['availability-zone']"
### What you recommended me gives me hostvar[<item>]['factor_zone']