Smaller Dockerfile for Docker Workshop

Dockerfile

FROM ubuntu:latest AS development
RUN apt-get update && apt-get install -y --no-install-recommends \
    default-jdk-headless maven git \
    && rm -rf /var/lib/apt/lists/*
RUN git clone https://github.com/OtherDevOpsGene/helloworld.git
WORKDIR helloworld
RUN mvn clean package

FROM openjdk:alpine AS runtime
COPY --from=development /helloworld/target/helloworld-1.1.jar /

CMD ["java", "-cp", "/helloworld-1.1.jar", \
    "com.coveros.demo.helloworld.HelloWorld"]