Heroku Web App Basic setting

Shopping list for setting up a Java EE Web App to be deployed on Heroku.

Assuming Maven, Java 11, Tomcat 9 as web server.

pom.xml: execution

Add to the build - plugins - plugin for maven-dependency-plugin, in the executions

<execution>
<phase>package</phase>
<goals>
  <goal>copy</goal>
</goals>
<configuration>
  <artifactItems>
	<artifactItem>
	  <groupId>com.heroku</groupId>
	  <artifactId>webapp-runner</artifactId>
	  <version>9.0.41.0</version>
	  <destFileName>webapp-runner.jar</destFileName>
	</artifactItem>
  </artifactItems>
</configuration>
</execution>

The element "version" is the Tomcat version we want to use

System properties

Root level, the system.properties should specify the Java version

java.runtime.version=11

Procfile

A one-liner, I split it here to improve readability

web: java $JAVA_OPTS
        -jar target/dependency/webapp-runner.jar
        --port $PORT target/*.war