org.springframework.boot:spring-boot-maven-plugin:1.5.10.RELEASE:repackage failed: Unable t o find main class - maven

Question

I have the following project structure :
parent pom
|
- Core module - pom
- Dist - pom
- Integration test - pom
Spring boot main class is in the core module. Integration tests will go into the integration tests folder.
I am trying to use spring-boot-maven-plugin for integration testing.
I have done the following pom configuration for the same in the integration-test module. The start-class property is set in the parent pom :
<plugin>
<groupId>org.springframework.boot</groupId>
<artifactId>spring-boot-maven-plugin</artifactId>
<configuration>
<mainClass>${start-class}</mainClass>
<layout>JAR</layout>
</configuration>
<executions>
<execution>
<goals>
<goal>repackage</goal>
</goals>
</execution>
<execution>
<id>pre-integration-test</id>
<goals>
<goal>start</goal>
</goals>
</execution>
<execution>
<id>post-integration-test</id>
<goals>
<goal>stop</goal>
</goals>
</execution>
</executions>
</plugin>
However I get the following error on mvn clean install on the parent pom :
[ERROR] Failed to execute goal org.springframework.boot:spring-boot-maven-plugin:1.5.10.RELEASE:start (pre-integration-test) on pro
ject: Spring application did not start before the configured timeout (30000ms -> [Help 1]
[ERROR]
Questions :
Is this project structure the best way to organize the integration
tests?
How and where do I give the path of the main class to the
spring-boot-maven-plugin correctly? It doesn't work even when I give
it in the integration module or parent pom even after giving a
relative path that you would normally do (e.g.
../core-module/)
maven-failsafe-plugin and spring annotations on the test class itself seem sufficient to run integration tests. So first of all is there any relation between integration tests and spring boot maven plugin? What is the need of spring boot maven plugin apart from packaging into an executable file. I have this confusion because it has goals like start pre-integration-test & post-integration-test but I fail to understand why its needed.
PS : I have checked few questions with a similar problem but none answer the questions I have asked for the given project structure.

Answer 1

I just ran into the same error as you (repackage failed: Unable t o find main class) trying to generalize some Spring code into a common spring boot project.
Turns out that it's not possible as a Spring boot project needs a class with a main method.
I solve my problem using direct dependencies to spring framework modules that I need, perhaps you can do that in your integration test project.
However, I don't know what kind of tests you are trying to run in the separate project, but tests concerning core module must be in the core module itself, using Spring test, not in a separate project. (use mock where needed).
Hope this helps.