Hello there, I am fairly new to using Maven having mostly done it through IDE or using Ant.
We are using Spring Boot, and their 1.4.x update changed the structure of their FAT jar mechanism such that many libraries that also scan for classes broke. There is a work around, basically it requires setting up a multi module project structure with a parent POM file. This apparently is somewhat common, but new to me. Previously we had just the one POM file that pulled in dependencies. Now in breaking things out, I am not able to rebuild our executable spring boot jar file. Basically I am trying to understand the parent\/child relationship. I thought if I put dependencies in the parent, they are automatically inherited by the children. However, in building, I get a lot of compiler errors for specific modules, such that I had to duplicate the dependency info in several modules. One thing I am confused about.. does Maven end up duplicating the JAR library dependencies for each module JAR it creates when more than one module uses the same dependency? When I do a mvn dependency:tree after a compile (which I was able to get to succeed... but still spring boot fails to start), I see the same dependencies in the module graphs. Does that mean they are stored more than once and that each uses their own module classloader at runtime? Or is this just showing the map via pom files, but in the FAT jar there is only one dependency jar? Second, I am unsure where to put the spring boot info to create the executable fat jar. From what I gather, my *-server module which contains the Application class that has the only main() method in my code and starts the spring boot app, is the module to put all the spring boot stuff. But, when I do this, I am not getting all the other modules pulled in to this jar.. such that it cant find classes that are needed when I try to execute it. I have added them as dependencies as well.. but then it begs the question.. what is the purpose of having a parent POM if I cant put the bits in that parent that instruct my final outcome? It seems I should be able to do so.. but because this parent POM structure must specify POM instead of JAR, it fails. So.. any help in understanding multi module and spring boot maven setup would be fantastic. Thank you.
