There are several reasons why you might want to migrate your app to OpenShift. One advantage is that the OpenShift platform itself is open source, not just the technologies and components that run on it. You can take the OpenShift Origin project and run your own cloud platform. OpenShift autoscales applications and natively supports MySQL and MongoDB, as well as PostgreSQL. Your app structure and config is created automatically thanks to the cartridge system and developers have shell access to the app containers -- called gears -- via SSH, which makes it easy to explore what is going on at runtime should you need to. OpenShift is also enterprise-grade, offering full Java EE support with JBoss, a high level of security backed by Red Hat Enterprise Linux and SELinux containerization, and an on-premise private cloud solution, OpenShift Enterprise.
OpenShift has excellent support for Java applications big and small. There is an array of preconfigured cartridges and quickstarts from Red Hat and the OpenShift community to help you quickly and easily get your app online, whether you want it to run on JBoss, Tomcat, Glassfish or Jetty. There is support for frameworks such as Spring and tools including Maven, Cron and Jenkins. OpenShift includes a DIY application cartridge that enables you to bring in additional technologies you might need; a lot of the time you will find someone in the community has already created a cartridge or quickstart for the tech you require.
Read more at Red Hat's OpenShift blog.