gradle + spring boot + docker

build.gradle

buildscript {
    ext {
        springBootVersion = '2.1.1.RELEASE'
    }
    repositories {
        mavenCentral()
    }
    dependencies {
        classpath("org.springframework.boot:spring-boot-gradle-plugin:${springBootVersion}")
    }
}

//apply plugin: 'java'
apply plugin: 'eclipse'
apply plugin: 'org.springframework.boot'
apply plugin: 'io.spring.dependency-management'
apply plugin: 'war'

group = 'com.example'
version = '0.0.1-SNAPSHOT'
sourceCompatibility = 1.8

repositories {
    mavenCentral()
}

springBoot {
    mainClassName = 'com.example.mainservice.MainApplication'
}
//springBoot {
//    mainClassName = "com.example.mainservice.MainApplication"
//}

dependencies {
    implementation('org.springframework.boot:spring-boot-starter-web')
    runtimeOnly('org.springframework.boot:spring-boot-devtools')
    compileOnly('org.projectlombok:lombok')
    testImplementation('org.springframework.boot:spring-boot-starter-test')
}

task resolveDependencies {
    doLast {
        project.rootProject.allprojects.each { subProject ->
            subProject.buildscript.configurations.each { configuration ->
                resolveConfiguration(configuration)
            }
            subProject.configurations.each { configuration ->
                resolveConfiguration(configuration)
            }
        }
    }
}

void resolveConfiguration(configuration) {
    if (isResolveableConfiguration(configuration)) {
        configuration.resolve()
    }
}

boolean isResolveableConfiguration(configuration) {
    def nonResolveableConfigurations = ['apiElements', 'implementation',
                                        'runtimeElements', 'runtimeOnly',
                                        'testImplementation', 'testRuntimeOnly',
                                        'generatedImplementation', 'generatedRuntimeOnly']

    if (nonResolveableConfigurations.contains(configuration.getName())) {
        return false
    }
    return true
}

Dockerfile

FROM gradle:5.0-alpine AS build

ENV APP_HOME=/app
USER root
RUN mkdir -p $APP_HOME/
WORKDIR $APP_HOME

# download dependencies
COPY build.gradle settings.gradle ./
RUN gradle resolveDependencies

# compile
COPY src ./src
RUN gradle build

# Based on https://github.com/GoogleContainerTools/distroless/blob/master/examples/java/Dockerfile
FROM gcr.io/distroless/java
USER root
COPY --from=build /app/build/libs/main-service-0.0.1-SNAPSHOT.war /
WORKDIR /
CMD ["main-service-0.0.1-SNAPSHOT.war"]

settings.gradle

rootProject.name = 'main-service'