If you are trying to deploy a Java Tomcat app on a Docker system, you might find other tutorials which will take you hours of heartache to get just right. How about deploying a full custom Tomcat app in just 30 seconds?

See For Yourself

Don't believe me? Just try these 10 simple steps:

$ brew install maven boot2docker # on OS X
$ boot2docker init ; boot2docker up # on OS X
$ sudo gem install bundler highline building

$ git clone https://github.com/jesperfj/webapp-with-jndi
$ cd webapp-with-jndi
$ mvn package
$ cd target/my-webapp
$ building -b http://github.com/jesperfj/buildpack-tomcat.git myapp
create Dockerfile
building docker build -t hhvm-app:latest .
hint: To run your app, try: docker run -d -p 8080 -e "PORT=8080" myapp
hint To re-build your app, try: docker build -t myapp .
$ JAVA_APP_ID=$(docker run -d -p 8080 -e "PORT=8080" myapp)
$ curl `docker port $JAVA_APP_ID 8080`/hello Hello World

The basic Heroku Java buildpack doesn't work with every Java app. If you run it from the jesperfj/webapp-with-jndi base directory it will fail. But if you use the jesperfj/buildpack-tomcat custom buildpack within the app's directory, everything works smoothly.

Conclusion

This is just a simple example of how much better the developer tooling around Docker has become over the last year. With Docker 1.0 just around the corner, there has never been a better time to start incorporating it into your daily workflow. If you are ready to get your feet wet with CoreOS, try our Building Your First App on CoreOS tutorial.