In a Nutshell: Deploying a Java webapp to Heroku

This post walks you through getting started with Heroku and deploying a simple Spring MVC web app.

  • Follow the Getting Started guide to get your Heroku Toolbelt setup
  • Login to Heroku from the commandline with ‘heroku login’
  • Since Heroku does not provide it’s own app server, you configure your pom.xml to pull in a dependency on a container, like Jetty (this is from the Getting Started with Spring MVC guide)
<plugin>
    <groupId>org.apache.maven.plugins</groupId>
    <artifactId>maven-dependency-plugin</artifactId>
    <version>2.3</version>
    <executions>
        <execution>
            <phase>package</phase>
            <goals><goal>copy</goal></goals>
            <configuration>
                <artifactItems>
                    <artifactItem>
                        <groupId>org.mortbay.jetty</groupId>
                        <artifactId>jetty-runner</artifactId>
                        <version>7.4.5.v20110725</version>
                        <destFileName>jetty-runner.jar</destFileName>
                    </artifactItem>
                </artifactItems>
            </configuration>
        </execution>
    </executions>
</plugin>

The Heroku Getting Started with Java instructions give some steps on how to run your app locally by running Java from the command line and passing a classpath pointing to your target dir, but this seems odd since Jetty is able to run from Mavan against your created war file or even the code compiled to your target dir using the ‘mvn jetty:run’ command. Add the following to the above <plugins> section to enable and use this approach instead:

<plugin>
<groupId>org.mortbay.jetty</groupId>
<artifactId>jetty-maven-plugin</artifactId>
</plugin>

  • Heroku uses a file named ‘Procfile’ in the root of your project to tell Heroku how to run your code. Add this file, and inside it add this one line
web: java $JAVA_OPTS -jar target/dependency/jetty-runner.jar --port $PORT target/*.war
  • Create your new app on Heroku with ‘heroku create –stack cedar’
  • Add and commit your code if you haven’t already, then push to your heroku remote git:
git add . git commit -m "commit comment" git push heroku master

At this point Heroku should build you app remotely and start it up.

If you see this error about the jetty-runner.jar missing, then you forgot to add the plugin part to your pom.xml to copy the jetty jar to the target/dependency dir:

Unable to access jarfile target/dependency/jetty-runner.jar

5 Replies to “In a Nutshell: Deploying a Java webapp to Heroku”

  1. Hi James – no major issues so far, the toolbelt command line tools are easy to use. The two Java related Getting Started guides (Getting Started with Java, and Getting Started with Spring MVC) have a few inconsistencies, but if you read the two together you can work out what’s going on. I’ll followup with you via email for some specifics.
    Thanks, Kevin

  2. How can I run a precompiled Java application (.jar file) on Heroku? I have an account and all, I just can’t figure out how to run a .jar.

  3. I don’t understand this. No matter where I add the xml code in my pom.xml, I get malformed pom. And where are we supposed to add the second part. It says “in your plugins section” but my pom, as it started, had no plugins section and the first part you have given has no plugins section either. Can you be more specific please?

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