How to register a variable in one role and use it in another one in Ansible?

I am trying to register a variable in a role and then use it in another one.

Here are the different files I'm using :

playbook.yml

---
- hosts: hostsgroup1
  [...]
  roles:
    - role1
- hosts: 127.0.0.1
  connection: local
  roles:
    - role2

role1/tasks/main.yml

- name: Example 1
  [...]
- name: Example 2
  shell:
    qm agent {{ VM_id }} network-get-interfaces |grep ip-address |grep '172.20' |grep -oE '((1?[0-9][0-9]?|2[0-4][0-9]|25[0-5])\.){3}(1?[0-9][0-9]?|2[0-4][0-9]|25[0-5])'
  register: var_role1

role2/tasks/main.yml

- name: Adding server to bastion
  ansible.builtin.debug:
    msg : Test {{ var_role1.stdout }}

For the information, the qm agent command gives me an IP address and I want to use it in the second role. But obviously, for now it displays an error when I execute the playbook :

fatal: [127.0.0.1]: FAILED! => {"msg": "The task includes an option with an undefined variable. The error was: \"hostvars['proxmoxhosts']\" is undefined\n\nThe error appears to be in '/root/ansible/roles/bastion_add/tasks/main.yml': line 3, column 3, but may\nbe elsewhere in the file depending on the exact syntax problem.\n\nThe offending line appears to be:\n\n# tasks file for bastion_add\n- name: Adding server to bastion\n  ^ here\n"}

To summarize, I want to use var_role1, registered in role1, in role2.

set_fact should do the trick.

- name: Example 2
  shell:
    qm agent {{ VM_id }} network-get-interfaces |grep ip-address |grep '172.20' |grep -oE '((1?[0-9][0-9]?|2[0-4][0-9]|25[0-5])\.){3}(1?[0-9][0-9]?|2[0-4][0-9]|25[0-5])'
  register: var_role1
- set_fact:
    var_role1: "{{ var_role1.stdout }}"