Dockerfile example

Dockerfile

# syntax=docker/dockerfile:1
ARG GRADLE_VERSION=8
ARG JDK_VERSION=17
ARG UBUNTU_CODENAME=jammy

ARG SOURCE_DIR=/home/jenkins
ARG UID=1000
ARG GID=1000
ARG APP_FAMILY=family
ARG APP_NAME=app

FROM gradle:${GRADLE_VERSION}-jdk${JDK_VERSION}-${UBUNTU_CODENAME} AS builder
SHELL [ "/bin/bash", "-euo", "pipefail", "-c" ]

# Create a custom Java runtime
RUN jlink \
    --verbose \
    --add-modules ALL-MODULE-PATH \
    --strip-debug \
    --no-header-files \
    --no-man-pages \
    --compress=2 \
    --output "/opt/company/openjdk"

ARG SOURCE_DIR
ARG UID
ARG GID

RUN install -d -o "$UID" -g "$GID" "$SOURCE_DIR"
WORKDIR $SOURCE_DIR

USER "$UID:$GID"
ENV GRADLE_OPTS="\
-Dorg.gradle.caching=true \
-Dorg.gradle.daemon=false \
-Dorg.gradle.logging.stacktrace=all \
-Dorg.gradle.vfs.watch=false \
-Dorg.gradle.warning.mode=all \
"
ENV GRADLE_USER_HOME="$SOURCE_DIR/.gradle"

COPY --chown=$UID:$GID *.gradle gradle.* ./
COPY --chown=$UID:$GID $APP_FAMILY-libs/*.gradle $APP_FAMILY-libs/gradle.* $APP_FAMILY-libs/
RUN gradle clean resolve

COPY --chown=$UID:$GID config/ config/
COPY --chown=$UID:$GID $APP_FAMILY-libs/ $APP_FAMILY-libs/
COPY --chown=$UID:$GID src/ src/
RUN gradle checkstyleMain :$APP_FAMILY-libs:jar bootJar

FROM builder AS test
CMD [ "gradle", "checkstyleTest", "test" ]

FROM ubuntu:${UBUNTU_CODENAME} AS runtime
SHELL [ "/bin/bash", "-euo", "pipefail", "-c" ]

RUN apt-get update \
    && apt-get install --yes --no-install-recommends -o Dir::Log=/dev/null -oDpkg::Options::=--log=/dev/null \
        curl \
        tini \
    && apt-get clean \
    && rm -rf /var/lib/apt/lists/*

ENV JAVA_HOME=/opt/java/openjdk
ENV PATH="${JAVA_HOME}/bin:${PATH}"
COPY --link --from=builder "/opt/company/openjdk" $JAVA_HOME

ARG APP_FAMILY
ARG APP_HOME="/home/$APP_FAMILY"
RUN groupadd -g 1000 "$APP_FAMILY" \
    && useradd -lmr -u 1000 -g "$APP_FAMILY" -d "$APP_HOME" -s /bin/bash "$APP_FAMILY" \
    && rm -rf /etc/{group,gshadow,passwd,shadow}-

WORKDIR $APP_HOME
ARG SOURCE_DIR
ARG APP_NAME
COPY --link --from=builder --chown=1000:1000 "$SOURCE_DIR/build/libs/${APP_FAMILY}-${APP_NAME}.jar" "$APP_HOME/app.jar"
USER $APP_FAMILY:$APP_FAMILY

LABEL io.company.app-family=$APP_FAMILY
LABEL io.company.app-name=$APP_NAME

ENTRYPOINT [ "tini", "-g", "--" ]
CMD [ "java", "--enable-preview", "-jar", "app.jar" ]