# Dockerfile.jenkins
# Use the official Jenkins image as a base
FROM jenkins/jenkins:lts-jdk17

# Pass the Docker group ID from the host as a build argument
ARG DOCKER_GID

# Switch to root user to install dependencies
USER root

# Install Docker CLI so Jenkins can interact with the host's Docker daemon
RUN apt-get update && apt-get install -y lsb-release sudo
RUN curl -fsSLo /usr/share/keyrings/docker-archive-keyring.asc \
  https://download.docker.com/linux/debian/gpg
RUN echo "deb [arch=$(dpkg --print-architecture) \
  signed-by=/usr/share/keyrings/docker-archive-keyring.asc] \
  https://download.docker.com/linux/debian \
  $(lsb_release -cs) stable" > /etc/apt/sources.list.d/docker.list
RUN apt-get update && apt-get install -y docker-ce-cli

# Create a 'docker' group with the host's GID to match permissions
# This is the key step to prevent the container from exiting
RUN if [ -n "$DOCKER_GID" ]; then groupadd -g $DOCKER_GID docker; else groupadd -g 999 docker; fi

# Add the 'jenkins' user to the docker group
RUN usermod -aG docker jenkins

# Switch back to the jenkins user
USER jenkins