The OpenShift diy cartridge documentation can be found at:

oo_cartridge_guide.html#diy

Prerequisite

Before we can start building the application, we need to have an OpenShift free account and client tools installed.

Step 1: Create DIY application

To create an application using client tools, type the following command:

rhc app create boot diy-0.1

This command creates an application boot using DIY cartridge and clones the repository to boot directory.

Step 2: Add MySQL cartridge to application

The application we are creating will use mysql database, hence we need to add appropriate cartridge to the application:

rhc cartridge add mysql-5.5 --app boot

After creating the cartridge, it is possible to check its status with the following command:

rhc cartridge status mysql-5.5 --app boot

Step 3: Delete Template Application Source code

OpenShift creates a template project that can be freely removed:

git rm -rf .openshift README.md diy misc

Commit the changes:

git commit -am "Removed template application source code"

Step 4: Pull Source code from GitHub

git remote add github https://github.com/jhcao23/openshift-diy-spring-boot-sample.git
git pull github master

Step 5: Push changes

The basic template is ready to be pushed:

git push origin master

The initial deployment (build and application startup) will take some time (up to several minutes). Subsequent deployments are a bit faster, although starting Spring Boot application may take even more than 2 minutes on small Gear:

Tomcat started on port(s): 8080/http
Started Application in 125.511 seconds

You can now browse to: http://boot-{namespace}.rhcloud.com/manage/health and you should see:

{"status":"UP","diskSpace":{"status":"UP","free":118865248256,"threshold":10485760},"db":{"status":"UP","database":"MySQL","hello":1}}

You can then browse to "/" to see the API root resource.

Step 6: Adding Jenkins

Using Jenkins has some advantages. One of them is that the build takes place in it's own Gear. To build with Jenkins, OpenShift needs a server and a Jenkins client cartridge attached to the application. Creating Jenkins application:

rhc app create ci jenkins

And attaching Jenkins client to the application:

rhc cartridge add jenkins-client --app boot

You can now browse to: http://ci-{namespace}.rhcloud.com and login with the credentials provided. When you make next changes and push them, the build will be triggered by Jenkins:

remote: Executing Jenkins build.
remote:
remote: You can track your build at https://ci-{namespace}.rhcloud.com/job/boot-build
remote:
remote: Waiting for build to schedule.........

And when you observe the build result, the application starts a bit faster on Jenkins:

Started Application in 52.391 seconds

Under the hood

original source: http://blog.codeleak.pl/2014/10/spring-boot-java-8-tomcat-8-on-openshift.html