ansible host file generator - add private ip for inventory hosts

hostnames.yml

    - name: "Build hosts file"
      lineinfile: 
        path: /etc/hosts 
        regexp: '.*{{ item }}$' 
        line: "{{ hostvars[item]['ansible_default_ipv4']['address'] }} {{ item }}"
      state: present
      with_items: 
      - "{{ groups['mongo-config'] }}"
      - "{{ groups['mongo-shards'] }}"
      - "{{ groups['mongo-main'] }}"