Create a sample infra with three servers:
2 - app servers
1 - db

Create /etc/Ansible/hosts with the following hosts:
[app]
192.168.60.4
192.168.60.5

# Database server
[db]
192.168.60.6

# Group 'multi' with all servers
[multi:children]
app
db

Start up the infra in VirtualBox: 
$ vagrant up

Start up the Node.js application server:
$ ansible-playbook repo.yml --sudo --extra-vars="node_apps_location=/usr/local/opt/node" --limit app

Test on your browser using one of the app's ip.