Spring Boot Can't find main class Multi module

Question

I am having difficulties telling Spring the location of the Main class. So far I have only managed to correctly specify where it is when it is in pictures-service module (ie, pictures-service/src/main/com.bachadiff.application/Application.java)

This is the file structure.

And this is the main gradle file.

       buildscript {
        repositories {
            mavenCentral()
        }
        dependencies {
            classpath("org.springframework.boot:spring-boot-gradle-plugin:2.0.2.RELEASE")
        }
    }

  plugins {
      id 'java'
      id 'java-library'
      id 'idea'
      id "org.springframework.boot" version "2.0.2.RELEASE"
      id "io.spring.dependency-management" version "1.0.5.RELEASE"
  }

    bootJar {
        baseName = 'com.bachadiff.pictures-service'
        version = '0.1.0'
        mainClassName = 'com.bachadiff.application.Application'

    }
    version = '0.1.0'

    repositories {
        mavenCentral()
    }

    sourceCompatibility = 1.8
    targetCompatibility = 1.8

    ext.common = [
            spring_web  : 'org.springframework.boot:spring-boot-starter-web:2.0.2.RELEASE',
            spring_rest : 'org.springframework.boot:spring-boot-starter-data-rest:2.0.2.RELEASE',
            spring_mongo: 'org.springframework.boot:spring-boot-starter-data-mongodb:2.0.2.RELEASE',
            spring_test : 'org.springframework.boot:spring-boot-starter-test'
    ]

    ext.test = [
            junit: 'junit:junit:4.12'
    ]

    dependencies {
        api 'org.springframework.boot:spring-boot-starter-web:2.0.2.RELEASE'
        api 'org.springframework.boot:spring-boot-starter-data-rest:2.0.2.RELEASE'
        api 'org.springframework.boot:spring-boot-starter-data-mongodb:2.0.2.RELEASE'
        compile project(':pictures-service-impl')
        testImplementation 'org.springframework.boot:spring-boot-starter-test'
    }

Answer 1

The mainClassName should consist out of the package and the class name itself, so in your case that should be:

mainClassName = 'com.bachadiff.application.Application'

And since you are saying that you have a multi-project build, you should put this in the build.gradle for the pictures-service-application project