[SOLVED] Ansible - How to 'wait_for' DNS to be available or How using lookup('dig') with 'until'

Ansible - How to 'wait_for' DNS to be available or How using lookup('dig') with 'until'

I made something that is working but I look for something more 'elegant' ;)

- name: Wait for DNS propagation
  ansible.builtin.shell:
    cmd: host "{{ vm_fqdn }}"
  register: dns_result
  until: dns_result.rc == 0
  retries: 30
  delay: 10

But previously I tried with a lookup and the community.general.dig

- name: Wait for DNS propagation
  ansible.builtin.set_fact:
    dns_result: "{{ lookup('community.general.dig', vm_fqdn)}}"
  until: dns_result == vm_ip
  retries: 30
  delay: 10

Unfortunately, even I added a register I couldn't get the dns_result variable updated after multiple tries. It's like the lookup happens only once on the first iteration, but is not 're-triggered' on the next try. So maybe it is the behavior of lookup or something else, but I'm curious to know.

Solution

You're using the lookup at the wrong point. It should be directly in the until, so that it is evaluated each time.

- name: Wait for DNS propagation
  debug:
    msg: waiting
  until: lookup('community.general.dig', vm_fqdn) == vm_ip
  retries: 30
  delay: 10