I have followed these tutorials to build Docker image for my Spring Boot application, which uses Maven as build tool. I am using boot2docker VM on top of Windows 10 machine, cloning my project to the VM from my Bitbucker repository.
https://spring.io/guides/gs/spring-boot-docker/
https://www.callicoder.com/spring-boot-docker-example/
I understand the instructions told, but, I failed to build a proper Docker image. Here's the things I tried.
Use the Spotify maven plugin for Dockerfile. Try to run ./mvnw to build the JAR as well as the Docker image. But, I don't have Java installed in the boot2docker. So the Maven wrapper ./mvnw cannot be run.
I tried to build the JAR through Dockerfile, which is based on the openjdk:8-jdk-alpine image. I added
RUN ./mvnw package
instruction in the Dockerfile. Then rundocker build -t <my_project> .
to build Docker image. It fails at the RUN instruction, claiming/bin/sh: mvnw: not found The command '/bin/sh -c mvnw package' returned a non-zero code: 127
My Dockerfile, located in the directory where the mvnw is located:
MAINTAINER myname
VOLUME /tmp
RUN ./mvnw package
ARG JAR_FILE=target/myproject-0.0.1-SNAPSHOT.jar
COPY ${JAR_FILE} app.jar
ENTRYPOINT ["java","-Djava.security.egd=file:/dev/./urandom","-jar","/app.jar"]
For 1, I need to have Java installed in the OS where the Docker engine resides. But I think it's not a good practice coz this lowers the portability.
For 2, first, I don't know how to run ./mvnw successfully in Dockerfile. Second, I'm not sure if it is a good practice to build the Spring Boot JAR through Dockerfile, coz I don't see any "Docker for Spring Boot" tutorial to tell to do so.
So, what is the best practice to solve my situation? I'm new to Docker. Comments and answers are appreciated!