How do I update an app on Compute Engine instances?

I am getting started with Google Compute Engine. I have a java Tomcat project, backed by MongoDB.

I don't have any problems with installing Tomcat and Mongo, and deploying my .war file through the Tomcat Manager.

I need to update my app frequently, with more features. If traffic increases, the autoscaler will increase the number of app servers.

So, how can I roll out an update to the multiple backend app servers, without having to go to each tomcat server, and deploying it (causes downtime and too much time to deploy). For example, say I have 150 app servers. How can I deploy my app to all of those servers at once with a single click? There is a similar to Amazon Web Services' OpsWorks and CodeDeploy.

Also, I have my project repo on BitBucket. I use Eclipse for my development.