Multiple module Spring Boot app - maven

Question

We have a Spring Boot app (exposing REST services) with multiple modules and for dev purposes we're using the default Spring Boot build approach - Maven builds it as one executable war file, that has Tomcat embedded into it.
For productive deployment purposes this doesn't work. We already have web app servers setup and we need a regular, non-executable war, that can be deployed on those servers. I already figured out, how I can build it.
We also will have another, related web apps (war files) deployed on the same productive servers (e.g. - simulator of the app). Of course, they will use (some of) the same modules, so the question it raises is how to setup maven to build the war and the module jars outside of it, so the other apps (war files deployed on the same server) could have dependencies on them. I couldn't find a good explanation/example how to do that.
Any ideas, links, blogs?

Answer 1

This is really more of a Maven question than Spring Boot. When you have a multi-module project Maven still creates individual artifacts for each module so you can still reference them as dependencies elsewhere.
For example in my setup with Spring boot I have the parent project and the modules underneath it. Most of the modules are jar artifacts, some with dependencies on other modules in the project and of course some external dependencies as well. By using the parent we can standardize some of the versions used in the dependencies using placeholders in the parent. Since the artifacts are still built and published separately you can reference them in other projects, which is what I believe you are asking.
For example (just the main tags and not all of them):
Parent:
<groupId>com.somecompany</groupId>
<artifactId>project-parent</artifactId>
<packaging>pom</packaging>
<version>1.1.2-SNAPSHOT</version>
<modules>
<module>module1</module>
<module>module2</module>
</modules>
Module1:
<parent>
<groupId>com.somecompany</groupId>
<artifactId>project-parent</artifactId>
<version>1.1.2-SNAPSHOT</version>
</parent>
<groupId>com.somecompany.tools</groupId>
<artifactId>project-tools-core</artifactId>
<version>1.1.2-SNAPSHOT</version>
<packaging>jar</packaging>
Module2:
<parent>
<groupId>com.somecompany</groupId>
<artifactId>project-parent</artifactId>
<version>1.1.2-SNAPSHOT</version>
</parent>
<groupId>com.somecompany.apps</groupId>
<artifactId>project-webapp</artifactId>
<version>1.1.2-SNAPSHOT</version>
<packaging>war</packaging>
<!-- dependency on other module -->
<dependency>
<groupId>com.somecompany.tools</groupId>
<artifactId>project-tools-core</artifactId>
<version>${project.version}</version>
</dependency>
Some Other Project:
<groupId>com.somecompany.apps</groupId>
<artifactId>project-webapp-services</artifactId>
<version>1.3.0-SNAPSHOT</version>
<packaging>war</packaging>
<!-- dependency on other module which is published -->
<dependency>
<groupId>com.somecompany.tools</groupId>
<artifactId>project-tools-core</artifactId>
<version>1.1.1</version>
</dependency>
So in this case assuming you had published version 1.1.1 of your parent and its modules you can have another project refer to any of those published artifacts. Maybe it is the release and publishing step you are missing.