Add Heroku support

Procfile

@@ -0,0 +1 @@
+web: java -jar server/target/lingo-websocket-server.jar

pom.xml

@@ -21,10 +21,20 @@
 	</properties>
 
 	<modules>
-		<module>client</module>
 		<module>client-api</module>
 		<module>common</module>
 		<module>server</module>
 	</modules>
 
+	<profiles>
+		<!-- Prevent client module from building on Heroku -->
+		<!-- Heroku's JDKs are headless -->
+		<profile>
+			<id>javafx</id>
+			<modules>
+				<module>client</module>
+			</modules>
+		</profile>
+	</profiles>
+
 </project>

server/pom.xml

@@ -46,6 +46,17 @@
 					<!-- Add src/main/config to the classpath -->
 					<folders>src/main/config</folders>
 				</configuration>
+				<executions>
+					<!-- Repackage as executable JAR (java -jar) -->
+					<execution>
+						<goals>
+							<goal>repackage</goal>
+						</goals>
+						<configuration>
+							<finalName>${project.artifactId}</finalName>
+						</configuration>
+					</execution>
+				</executions>
 			</plugin>
 		</plugins>
 	</build>

server/src/main/java/lingo/server/LingoServer.java

@@ -7,6 +7,13 @@ import org.springframework.boot.autoconfigure.SpringBootApplication;
 public class LingoServer {
 
 	public static void main(String[] args) {
+
+		// Heroku dynamically assigns a port
+		final String webPort = System.getenv("PORT");
+		if (webPort != null && !webPort.isEmpty()) {
+			System.setProperty("server.port", webPort);
+		}
+
 		SpringApplication.run(LingoServer.class, args);
 	}
 

system.properties

@@ -0,0 +1 @@
+java.runtime.version=1.8