Scalingo supports Spring Boot as well as any other Java framework deployable with Maven. The only condition is to configure your application to listen on the PORT environment variable.

The application can be deployed as a .jar file or a standalone .war file. This page describes how to achieve both.

WAR or JAR

Your Spring Boot application can be packaged as a jar or as a war (see the Spring documentation here).

The way you choose to package your application changes the way you deploy on Scalingo.

Listen on ${PORT}

For both WAR and JAR deployments, you need to specify the good port to listen to in your Spring Boot application configuration file.

server:
    port: ${PORT}

As a JAR

Deploying a JAR file does not require any extra stuff to work with Scalingo.

Define your Procfile

One still need to describe in a Procfile how the application should be started. Add a Procfile file at the root of your project:

To define how to start your application, you need to create a Procfile file at the root of your project. More documentation about Procfile.

web: java $JAVA_OPTS -jar target/*.jar --spring.profiles.active=YOUR_PROD_PROFILE

Don’t forget to specify the production profile (if you use Spring profiles) as a parameter.

Commit your Procfile and push your modifications to deploy your application.

As a WAR

This one is more complicated as we need to:

• replace the classic web.xml file
• modify the maven or Gradle build file
• slightly change the Procfile that works with standard war files

web.xml

To replace the classic web.xml file, you have to create a new class that sources the Spring Boot application.

public class ApplicationWebXml extends SpringBootServletInitializer {

    @Override
    protected SpringApplicationBuilder configure(SpringApplicationBuilder application) {
        return application.sources(Application.class);
    }

}

pom.xml (or build.gradle)

1. Avoid conflicts between Tomcat

<dependency>
    <groupId>org.springframework.boot</groupId>
    <artifactId>spring-boot-starter-tomcat</artifactId>
    <!-- Add this -->
    <scope>provided</scope>
</dependency>

1. Add webapp-runner 8.0.24.0 (Spring Boot needs Tomcat 8.x for websockets)

<build>
  ...
  <plugins>
    ...
    <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>com.github.jsimone</groupId>
                <artifactId>webapp-runner</artifactId>
                <version>8.0.24.0</version>
                <destFileName>webapp-runner.jar</destFileName>
              </artifactItem>
            </artifactItems>
          </configuration>
        </execution>
      </executions>
    </plugin>
  </plugins>
</build>

Define your Procfile

To define how to start your application, you need to create a Procfile file at the root of your project. More documentation about Procfile.

web: java $JAVA_OPTS -Dspring.profiles.active=YOUR_PROD_PROFILE -jar target/dependency/webapp-runner.jar --port $PORT --expand-war target/*.war

Don’t forget to specify the production profile (if you use Spring profiles) as a parameter.

Commit your pom.xml and your Procfile, and push the modifications to deploy your application.