Dockerfile

#### GLOBAL
ARG PROJECT_DIR="/project"


#### COMPILE STAGE
#FROM maven:3.6.3-jdk-11-openj9 as compile
FROM maven:3.8.7-eclipse-temurin-11 as compile

# Args
ARG PROJECT_DIR

# Ensure up to date / patched OS
RUN  apt-get -qq update \
  && DEBIAN_FRONTEND=noninteractive apt-get -qq upgrade -y \
  && apt-get -qq clean \
  && rm -rf /tmp/* /var/lib/apt/lists/*

# Create non-root user / group to run
RUN  groupadd --gid 1000 java_group \
  && useradd --uid 1000 --gid java_group --shell /bin/bash --create-home java_user \
  && mkdir -p /mvn/repository && chown -R java_user:java_group /mvn \
  && mkdir ${PROJECT_DIR} && chown -R java_user:java_group ${PROJECT_DIR}

# Switch to non-root user and workdir
USER java_user:java_group
WORKDIR ${PROJECT_DIR}

# Copy files
COPY --chown=java_user:java_group src ${PROJECT_DIR}/src/
COPY --chown=java_user:java_group pom.xml ${PROJECT_DIR}

# Package it
RUN mvn --no-transfer-progress clean package

# Extract the jar
RUN mkdir -p target/dependency && (cd target/dependency; jar -xf ../*.jar)


#### BUILD STAGE
#FROM adoptopenjdk:11-jdk-openj9
FROM eclipse-temurin:11

# Build args
ARG ARTIFACT_TITLE=springboot-swagger-jpa-stack
ARG ARTIFACT_VERSION=1.0.0-SNAPSHOT
ARG PROJECT_DIR

# Envs
ENV JVM_ARGS=""

# Ensure up to date / patched OS
RUN  apt-get -qq update \
  && DEBIAN_FRONTEND=noninteractive apt-get -qq upgrade -y \
  && apt-get -qq clean \
  && rm -rf /tmp/* /var/lib/apt/lists/*

# Create non-root user / group to run
RUN groupadd --gid 1000 java_group \
  && useradd --uid 1000 --gid java_group --shell /bin/bash --create-home java_user \
  && mkdir /app && chown -R java_user:java_group /app

# Switch to non-root user and workdir
USER java_user:java_group
WORKDIR /app

# Label the image
LABEL org.opencontainers.image.title="${ARTIFACT_TITLE}"
LABEL org.opencontainers.image.version="${ARTIFACT_VERSION}"

# Layering the app instead of using the fat jar 
COPY --from=compile ${PROJECT_DIR}/target/dependency/BOOT-INF/lib /app/lib
COPY --from=compile ${PROJECT_DIR}/target/dependency/META-INF /app/META-INF
COPY --from=compile ${PROJECT_DIR}/target/dependency/BOOT-INF/classes /app

# Expose ports
EXPOSE 8080
EXPOSE 8443

# Prepare and set the entry point
RUN echo '#!/bin/sh' > start.sh \
    && echo "exec java \${JVM_ARGS} \${JAVA_TOOL_OPTIONS} -cp /app:/app/lib/* -Djava.security.egd=file:/dev/./urandom \\" >> start.sh \
    && cat /app/META-INF/MANIFEST.MF | grep 'Start-Class: ' | cut -d' ' -f2 | tr -d '\r\n' >> start.sh \
    && echo "" >> start.sh \
    && cat start.sh \
    && chmod +x start.sh
ENTRYPOINT [ "/app/start.sh" ]