Thursday, April 17, 2014

Using free openshift java PAAS, to run a web application on an online version of tomcat

Many times you have a war file, that you would like to deploy such that the application becomes available online.A classical use case is using a REST service as stub for your mobile app or thin client web app.

Openshift online PAAS is an easy solution for such free hotsitng of a java web application

Create a free account at open shift online 
Download their rhc command line tool
Fire following command to create 1 of 3 free apps, where name of new hosted web app is for example say, restgrails

rhc create-app restgrails tomcat-7

Go to the open shift web console and note down the ssh url of the git repository
setup ssh keys for the open shift git repo using command

rhc setup

If required, place the keys generated in <user-dir>\.ssh into <git-install-dir>\.ssh

fire following command on your local machine

git clone <git_url> restgrails

on your local machine the above git command will create a new directory called restgrails and checkout default web app from openshift git repo to your local machine

cd restgrails

Fire following commands to get rid of the default web app's src and pom.xml, since we will deploy a ready made war file onto the openshift PAAS

git rm -rf src/ pom.xml

git commit -am "deleted default source code"

Now prepare the ready made war file for deploying onto open shift

copy war file to restgrails/webapps/
rename war file to ROOT.war  --this is important if you want to map your webapp to the openshift online app URL

git add .
git commit -am "added new root.war to webapps"
git push --force

Above git push command, will trigger a deploy of the war file into the remote tomcat on open shift and soon the web app will become available online as say

you can tail the tomcat server logs with the following command
rhc tail restgrails

For databases, openshift online does support databases like mongodb, mysql and postgresql, so if your app uses hibernate, it can easily be configured to use online database like say mysql or postgresql, while running it online

to check logs

Go to openshift web console, and click on Remote access, want to login to your application

Fire ssh command, in textbox on web console, from your dos prompt

You will be get logged-in to the VM.
Here give following commands:

[ ]\> find  . -name *.log
find: `./.tmp': Permission denied
find: `./.sandbox': Permission denied
find: `./.ssh': Permission denied

[ ]\> tail -f ./app-root/logs/jbossews.log

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