Dockerfile

FROM eclipse-temurin:17.0.7_7-jdk-focal as jre-build

# Generate smaller java runtime without unneeded files
# for now we include the full module path to maintain compatibility
# while still saving space
RUN jlink \
         --add-modules ALL-MODULE-PATH \
         --no-man-pages \
         --compress=2 \
         --output /javaruntime

FROM debian:bullseye-20230502

ARG user=jenkins
ARG group=jenkins
ARG uid=1000
ARG gid=1000
ARG JENKINS_AGENT_HOME=/home/${user}

ENV JENKINS_AGENT_HOME=${JENKINS_AGENT_HOME}
ARG AGENT_WORKDIR="${JENKINS_AGENT_HOME}"/agent
# Persist agent workdir path through an environment variable for people extending the image
ENV AGENT_WORKDIR=${AGENT_WORKDIR}

RUN groupadd -g ${gid} ${group} \
    && useradd -d "${JENKINS_AGENT_HOME}" -u "${uid}" -g "${gid}" -m -s /bin/bash "${user}" \
    # Prepare subdirectories
    && mkdir -p "${JENKINS_AGENT_HOME}/.ssh/" "${AGENT_WORKDIR}" "${JENKINS_AGENT_HOME}/.jenkins" \
    # Make sure that user 'jenkins' own these directories and their content
    && chown -R "${uid}":"${gid}" "${JENKINS_AGENT_HOME}" "${AGENT_WORKDIR}"

RUN apt-get update \
    && apt-get install --no-install-recommends -y \
       git-lfs \
       less \
       netcat-traditional \
       openssh-server \
       patch \
    && rm -rf /var/lib/apt/lists/*

# setup SSH server
RUN sed -i /etc/ssh/sshd_config \
        -e 's/#PermitRootLogin.*/PermitRootLogin no/' \
        -e 's/#RSAAuthentication.*/RSAAuthentication yes/'  \
        -e 's/#PasswordAuthentication.*/PasswordAuthentication no/' \
        -e 's/#SyslogFacility.*/SyslogFacility AUTH/' \
        -e 's/#LogLevel.*/LogLevel INFO/' && \
    mkdir /var/run/sshd

# VOLUME directive must happen after setting up permissions and content
VOLUME "${AGENT_WORKDIR}" "${JENKINS_AGENT_HOME}"/.jenkins "/tmp" "/run" "/var/run"
WORKDIR "${JENKINS_AGENT_HOME}"

ENV LANG='C.UTF-8' LC_ALL='C.UTF-8'

ENV JAVA_HOME=/opt/java/openjdk
ENV PATH="${JAVA_HOME}/bin:${PATH}"
COPY --from=jre-build /javaruntime $JAVA_HOME

RUN echo "PATH=${PATH}" >> /etc/environment
COPY setup-sshd /usr/local/bin/setup-sshd

EXPOSE 22

ENTRYPOINT ["setup-sshd"]

LABEL \
    org.opencontainers.image.vendor="Jenkins project" \
    org.opencontainers.image.title="Official Jenkins SSH Agent Docker image" \
    org.opencontainers.image.description="A Jenkins agent image which allows using SSH to establish the connection" \
    org.opencontainers.image.url="https://www.jenkins.io/" \
    org.opencontainers.image.source="https://github.com/jenkinsci/docker-ssh-agent" \
    org.opencontainers.image.licenses="MIT"