Merge pull request #142 from fiunchinho/feature/improve_maven_dockerfile

Using multi-stage to compile the application

packs/java/Dockerfile

@@ -1,3 +1,10 @@
-FROM maven:onbuild
+FROM maven:3.5-jdk-8-alpine as BUILD
+
+COPY . /usr/src/app
+RUN mvn -f /usr/src/app/pom.xml clean package
+
+FROM openjdk:8-jdk-alpine
 EXPOSE 4567
-CMD ["java", "-jar", "target/helloworld-jar-with-dependencies.jar"]
+COPY --from=BUILD /usr/src/app/target/*.jar /opt/app.jar
+WORKDIR /opt
+CMD ["java", "-jar", "app.jar"]