Play framework on OpenShift Express

This git repository helps you get up and running quickly with a Play framework application on OpenShift Express.

Running on OpenShift

Register at http://openshift.redhat.com/, and then create a raw (do-it-yourself) application:

rhc app create -a play -t diy-0.1 -l yourlogin@yourmail.com

Add this upstream play-example repo:

cd play
git remote add quickstart -m master https://github.com/opensas/play-example.git
git pull -s recursive -X theirs quickstart master

Then push the repo upstream:

git push

That's it, you can now see your running application at:

http://play-yournamespace.rhcloud.com

If you are a perfectionist, now it would be a good time to change your application.name setting in conf/application.conf to match your application.

Working with a mysql database

Just issue:

rhc app cartridge add -a play -c mysql-5.1

Don't forget to write down the credentials.

Then uncomment the following lines from your conf/application.conf, like this:

# openshift mysql database
%openshift.db.url=jdbc:mysql://${OPENSHIFT_DB_HOST}:${OPENSHIFT_DB_PORT}/${OPENSHIFT_APP_NAME}
%openshift.db.driver=com.mysql.jdbc.Driver
%openshift.db.user=admin
%openshift.db.pass=<write your password here>

You can manage your new MySQL database by embedding phpmyadmin-3.4.

rhc app cartridge add -a play -c phpmyadmin-3.4

It's also a good idea to create a different user with limited privileges on the database.

Updating your application

To deploy your changes to openshift just add your changes to the index, commit and push:

git add . -A
git commit -m "a nice message"
git push origin

Working with modules

You don't have to do anything special, just add your modules to conf/dependencies.yml. Openshift will run

play deps --forProd --clearcache

before starting you application, to make sure that your dependencias are all upto date.

Trouble shooting

To find out what's going on in openshift, issue

rhc app tail -a play

If you feel like investigating further, you can

rhc app show -a play

Application Info
================
play
    Framework: raw-0.1
    Creation: 2012-03-18T12:39:18-04:00
    UUID: youruuid
    Git URL: ssh://youruuid@play-yournamespace.rhcloud.com/~/git/raw.git/
    Public URL: http://play-yournamespace.rhcloud.com

Then you can connect using ssh like this:

ssh youruuid@play-yournamespace.rhcloud.com

Having a look under the hood

.openshift/action_hooks/pre_build does the following everytime you push changes

• reads play version from openshift.play.version at application.conf (1.2.4 by default)

• checks if the desired version is installed, if not it downloads and installs play framework at $OPENSHIFT_DATA_DIR

• removes any other play framework version

then .openshift/action_hooks/start goes like this

• it executes .openshift/action_hooks/stop to stop the application

• cleans environment and update dependencies using openshift.deps.params for play deps parameters (uses "--forProd --clearcache" by default)

    play clean
    play deps $DEPS_PARAMS -Divy.hom=/tmp/ivy2

• finally it starts the application, using openshift.id (by default the configuration id to use is openshift). You can specify additional parameters with openshift.play.params.

    play start --%ID $PLAY_PARAMS

By default play will run in production mode, you can change it setting %openshift.application.mode=dev in application.conf. The server will listen to ${OPENSHIFT_INTERNAL_PORT} at ${OPENSHIFT_INTERNAL_IP}.

• .openshift/action_hooks/stop just tries to kill the server.pid process, and then checks that no "java" process is running. If it's there, it tries five times to kill it nicely, and then if tries another five times to kill it with -SIGKILL.

Acknowledgments

I couldn't have developed this quickstart without the help of marekjelen who answered my questions on stackoverflow and who also shared his JRuby quickstart repo. (I know, open source rocks!)

It was also of great help Grant Shipley's article on building a quickstart for openshift.

Play framework native support for openshift was a long awaited and pretty popular feature (you are still on time to vote for it here). So it's a great thing that Red Hat engineers came out with this simple and powerful solution, that basically let's you implement any server able to run on a linux box. Kudos to them!!!

Licence

This project is distributed under Apache 2 licence.