How do I dynamically take variables from previous plays in Ansible?

Example, I have 3 tasks, which are registered ec21, ec22 and ec23.

ec22 runs when ec21 fails, and ec23 runs when ec22 fails.

Now, I have another task below it which is :

- name: Add new instance to host group
  add_host:
    hostname: "{{ item.private_ip }}"
    groupname: launched
  with_items: "{{ ec2x.instances }}"

where ec2xis any of the previous tasks.

So, how do I set ec2x here? cause, Any of my 3 tasks can run. So, it can be ec21 or ec22 or ec23. So, how do I dynamically write that in the adding task after them?

It feels dirty, but I guess something like that would work:

- name: ec21
  [...]
  register: ec21_result

- set_fact: end_result= "{{ ec21_result }}"
  when: ec21_result|succeeded

- name: ec22
  [...]
  register: ec22_result
  when: ec21_result|failed

- set_fact: end_result= "{{ ec22_result }}"
  when: ec22_result|succeeded

- name: ec23
  [...]
  register: ec23_result
  when: ec22_result|failed

- set_fact: end_result= "{{ ec23_result }}"
  when: ec23_result|succeeded

- name: Add new instance to host group
  add_host:
    hostname: "{{ item.private_ip }}"
    groupname: launched
  with_items: "{{ end_result.instances }}"

Basically setting the end_result as soon as you succeed a play.

StackExchange DevOps Q#1110, answer score: 5