Restart Servers Serially on Different Servers

[Suvelee Sarpotdar]

I have two groups of hosts - app and gateway. Each app talks to corresponding gateway. I am upgrading app to a new version serially (4 at a time) and restarting it. I would like to restart the corresponding gateway after the app is restarted. Can I use handler with include file that restarts the gateway on different host? Or is there a better a way to do this?

Host: app

serial: 4

roles:

   - upgrade_app

   - restart

Host: gateway

serial: 4

roles:

   - restart

Can the above 4 lines be added in playbook that can be included as handler in app playbook?

Thanks,

Suvelee