Maven Multi Module Spring Boot Project

Question

I am trying to create a multi module project that contains two module, core and web. They are both Spring Boot projects that I generated on Spring Initialzer. I setup the Maven POM files but I'm having issues getting it to deploy. However I am confused how the configuration is going to work.

The core module is going to contain the domain object / entities, Spring Data JPA repositories, services, and will be packaged as a JAR. The Web module is going to have Spring Security, the controllers, and the views. It will be packaged as a WAR.

The normal structure of a Spring Boot project looks like the following

/
pom.xml
src/
..main/
....com/
......example/
........app/
..........Application.java
..resources/
....application.properites

I essentially have two of these and two Spring Boot application / configuration / initialization classes.

My questions are

Do the properties have to live in a single configuration file or can I have two application.properities, one the core jar, and one for the WAR?

Can I have the following in my core.jar

import org.springframework.boot.SpringApplication;
import org.springframework.boot.autoconfigure.SpringBootApplication;

@SpringBootApplication
public class TimesheetCoreApplication {

  public static void main(String[] args) {
    SpringApplication.run(TimesheetCoreApplication.class, args);
  }
}

Along with the following two in my web.war

import org.springframework.boot.SpringApplication;
import org.springframework.boot.autoconfigure.SpringBootApplication;

@SpringBootApplication
public class TimesheetWebApplication {

    public static void main(String[] args) {
        SpringApplication.run(TimesheetWebApplication.class, args);
    }
}

AND

import org.springframework.boot.builder.SpringApplicationBuilder;
import org.springframework.boot.context.web.SpringBootServletInitializer;

public class ServletInitializer extends SpringBootServletInitializer {

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

}

Since Spring Boot does a lot of auto configuration, will they step over each other with the configuration, either conflicting or overriding one another?

What is the best way to approach this? I would like to leverage Spring Boot if possible.

Your core application is going to do nothing as it is just another jar like anyother included in a web project. So only your web jar will do something, are you really sure you want your core application to be a spring boot application and not only the web? What is the point if it isn't a standalone application and only for embedding. — M. Deinum

Hbargujar Hbargujar · Accepted Answer · 2016-02-12T02:59:13

your design is slightly incorrect, if your core project is going to have domain entities, repositories etc. it need not be a BOOT Application. As you said, this is going to be a Jar.

Now you make the your web application a Boot Application with dependency on the core module jar. You can define .properties or .yml in the Boot Application and you are good to go.

The problem with Spring Initializer is, it gives you an impression that all the code need to reside under a single project or module.

This is typical project I follow for my Applications

project-core-module (packaging Jar -> domain entities, repositories etc)
project-service-module (boot -> configuration, rest interface, security etc)
project-system-tests (runs on compile time and certify the build)

Now you bind core and system module with service module as dependency.

Maven Multi Module Spring Boot Project

3 Answers