55.3 OpenShift

OpenShift is the RedHat public (and enterprise) PaaS solution. Like Heroku, it works by running scripts triggered by git commits, so you can script the launching of a Spring Boot application in pretty much any way you like as long as the Java runtime is available (which is a standard feature you can ask for at OpenShift). To do this you can use the DIY Cartridge and hooks in your repository under .openshift/action_hooks:

The basic model is to:

1. Ensure Java and your build tool are installed remotely, e.g. using a pre_build hook (Java and Maven are installed by default, Gradle is not)

2. Use a build hook to build your jar (using Maven or Gradle), e.g.

   #!/bin/bash
   cd $OPENSHIFT_REPO_DIR
   mvn package -s .openshift/settings.xml -DskipTests=true

3. Add a start hook that calls java -jar …​

   #!/bin/bash
   cd $OPENSHIFT_REPO_DIR
   nohup java -jar target/*.jar --server.port=${OPENSHIFT_DIY_PORT} --server.address=${OPENSHIFT_DIY_IP} &

4. Use a stop hook (since the start is supposed to return cleanly), e.g.

   #!/bin/bash
   source $OPENSHIFT_CARTRIDGE_SDK_BASH
   PID=$(ps -ef | grep java.*\.jar | grep -v grep | awk '{ print $2 }')
   if [ -z "$PID" ]
   then
       client_result "Application is already stopped"
   else
       kill $PID
   fi

5. Embed service bindings from environment variables provided by the platform in your application.properties, e.g.

   spring.datasource.url: jdbc:mysql://${OPENSHIFT_MYSQL_DB_HOST}:${OPENSHIFT_MYSQL_DB_PORT}/${OPENSHIFT_APP_NAME}
   spring.datasource.username: ${OPENSHIFT_MYSQL_DB_USERNAME}
   spring.datasource.password: ${OPENSHIFT_MYSQL_DB_PASSWORD}

There’s a blog on running Gradle in OpenShift on their website that will get you started with a gradle build to run the app.