January 2014 – Shekhar Gulati

How to Host your Java EE Application with Auto-scaling

OpenShift is an auto-scalable Platform as a Service. Auto-scalable means OpenShift can horizontally scale your application up or down depending on the number of concurrent connections. OpenShift supports the JBoss application server, which is a certified platform for Java EE 6 development. As an OpenShift user, you have access to both the community version of JBoss and JBoss EAP 6(JBoss Enterprise Application Platform) for free. In this blog post, we will learn how to host a scalable Java EE 6 application using a JBoss EAP 6 server cluster running on OpenShift. Read the full blog here https://www.openshift.com/blogs/how-to-host-your-java-ee-application-with-auto-scaling

Solving Pusher HTTPS Issue

If you use Pusher then you might face following error. The error happens when you try to use Pusher client library from https.

The page at 'https://shekhargulati.com/blog/1#/' was loaded over HTTPS, but ran insecure content from 'http://js.pusher.com/2.1/pusher.min.js': this content should also be loaded over HTTPS.

To fix this error, you should use Pusher Cloudfront CDN version as shown below. In your HTML or other template use following. Replace 2.1 with your own version.

<script src="//d3dy5gmtp8yhk7.cloudfront.net/2.1/pusher.min.js" type="text/javascript"></script>

How to run Grails Application with Jenkins on OpenShift

Yes, you can run Grails applications on OpenShift. Follow the steps mentioned below to deploy Grails apps via Jenkins on OpenShift.

Step 1 : Create Tomcat 7 application with Jenkins

$ rhc app-create grailsapp tomcat-7 --enable-jenkins

Step 2 : Delete template code

$ cd grailsapp
$ git rm -rf src/ pom.xml
$ git commit -am "deleted template code"

Step 3: Generate Grails app
Use grails command line or IDE to generate a Grails project.

Step 4: Copy the Grails app
Copy the source code of your grails app in the grailsapp folder. The grailsapp corresponds to OpenShift application.

Step 5: Create pre_build action hook
Create an OpenShift action hook

touch .openshift/action_hooks/pre_build
chmod +x .openshift/action_hooks/pre_build

Copy the following in pre_build hook

#!/bin/bash
# This is a simple script and will be executed on your CI system if
# available.  Otherwise it will execute while your application is stopped
# before the build step.  This script gets executed directly, so it
# could be python, php, ruby, etc.
set -x
if [ ! -d $OPENSHIFT_DATA_DIR/grails-2.3.4 ]
then
        mkdir $OPENSHIFT_DATA_DIR/.grails
        cd $OPENSHIFT_DATA_DIR
        wget http://dist.springframework.org.s3.amazonaws.com/release/GRAILS/grails-2.3.4.zip
        unzip grails-2.3.4.zip
        rm -f grails-2.3.4.zip
fi

Step 6: Create build action hook
Create an OpenShift action hook

touch .openshift/action_hooks/build
chmod +x .openshift/action_hooks/build

Copy the following in build hook

#!/bin/bash
# This is a simple script and will be executed on your CI system if
# available.  Otherwise it will execute while your application is stopped
# before the build step.  This script gets executed directly, so it
# could be python, php, ruby, etc.
set -x
export GRAILS_HOME=$OPENSHIFT_DATA_DIR/grails-2.3.4
export PATH=$GRAILS_HOME/bin:$PATH
cd $OPENSHIFT_REPO_DIR
export GRAILS_OPTS="-Xmx512m -Xms256m -XX:MaxPermSize=256m"
grails -Dgrails.work.dir=$OPENSHIFT_DATA_DIR.grails prod war

Step 7: Commit and push the changes

Commit and push the changes

$ git add .
$ git commit -am "app"
$ git push

Now watch your Jenkins build. If it fails, I guess it would be because of memory issues. Try and use bigger gear sizes. Grails is memory hungry.

Github repository with sample app code https://github.com/shekhargulati/grails-jenkins-openshift-example