ansible/playbooks/test_replace.yml

- hosts: nas
  name: Sync mailu
  ignore_unreachable: false
  vars:
      app_path: "{{ 'localhost:80' | regex_replace('^(?P<host>.+):(?P<port>\\d+)$', '\\g<host>, \\g<port>') }}"
  tasks:
    - name: Print the gateway for each host when defined
      ansible.builtin.debug:
        msg: var is "{{ app_path }}"