gather_interfaces.yml

---
- hosts: quagga-routers
  tasks:
    # - name: loop through loopback addresses
    #   shell: "ip -o link show | awk -F': ' '{ print $2 }'"
    #   register: "ip_links"

    - debug: msg=Found
      when: item.int in ansible_interfaces
      with_items: '{{ quagga_interfaces_lo }}'