Dockerfile for Java/Kotlin Maven Build

Dockerfile

# Part 1: Build the app using Maven
FROM maven:3.6.0-jdk-8-alpine

## download dependencies
ADD pom.xml /
RUN mvn verify clean
## build after dependencies are down so it wont redownload unless the POM changes
ADD . /
RUN mvn package

# Part 2: use the JAR file used in the first part and copy it across ready to RUN
FROM openjdk:8-jdk-alpine
WORKDIR /root/
## COPY packaged JAR file and rename as app.jar 
## → this relies on your MAVEN package command building a jar 
## that matches *-jar-with-dependencies.jar with a single match
COPY --from=0 /target/*-jar-with-dependencies.jar app.jar 
ENTRYPOINT ["java","-Djava.security.egd=file:/dev/./urandom","-jar","./app.jar"]