set_paths.yml

---
- hosts: my_routers
  gather_facts: no
  connection: local

  tasks:
    # load all paths parameters into `paths` variable  
    - name: load defined paths
      include_vars:
        file: paths.yml
        name: paths

    # test prefered path using ping 
    - name: test paths using ping
      ios_ping:
        dest: "{{ paths[paths['prefered']][inventory_hostname]['next_hop'] }}" 
        count: 3
      register: result_of_ping
      ignore_errors: True

    - name: select backup path
      set_fact: {'active_path': "{{ paths['backup'] }}"}
      when: result_of_ping|failed

    - name: select prefered path
      set_fact: {'active_path': "{{ paths['prefered'] }}"}
      when: result_of_ping|succeeded

    # start a block to remove old routes and install new ones   
    - name: remove old path and setup the new one
      block:
        - name: remove old routes
          ios_config:
            lines:
              - "no ip route {{paths[active_path][inventory_hostname]['prefix']}} {{paths[active_path][inventory_hostname]['mask']}}"
            authorize: yes

        - name: setup new routes 
          ios_static_route:
            prefix : "{{ paths[active_path][inventory_hostname]['prefix'] }}"
            mask: "{{ paths[active_path][inventory_hostname]['mask'] }}"
            next_hop: "{{ paths[active_path][inventory_hostname]['next_hop'] }}"
            authorize: yes
      rescue:
        - debug:
            msg: "An Error occured => rollback"