Dockerfile

# We use Ubuntu as a base because it comes with frequent updates and a wide variety
# of packages.
ARG UBUNTU_VERSION=24.04
FROM docker.io/ubuntu:${UBUNTU_VERSION}

# The user from the Ubuntu base image is `ubuntu`. We provide environment variables
# that we need later anyway right here.
ENV USER=ubuntu
ENV HOME="/home/${USER}"

# These environment variables are used by APT and dpkg. Their # values make APT and
# dpkg behave as non-interactive.
ENV DEBIAN_FRONTEND=noninteractive
ENV DEBCONF_NONINTERACTIVE_SEEN=true

# These variables are used to determine the version of Hermes this this image is base
# upon. To propagate the version, a more descriptive ENV variable is used too.
ARG HERMES_VERSION='v3.0.2'
ENV DEV_CONTAINER_BASE_HERMES_VERSION=${HERMES_VERSION}

# hadolint ignore=DL3005,DL3008
RUN <<EOM
#! /usr/bin/env -S bash -o pipefail -eE -u
  shopt -s inherit_errexit

  # We ensure we use the most recent versions of packages from the base image. Here,
  # `dist-upgrade` is okay as well, because we do not have prior commands installing
  # software that could potentially be damaged.
  apt-get --yes update
  apt-get --yes dist-upgrade
  apt-get --yes install --no-install-recommends \
    apt-utils ca-certificates curl dialog doas file locales
  # We also perform a proper cleanup
  apt-get --yes autoremove
  apt-get --yes clean
  rm -rf /var/lib/apt/lists/* /tmp/*

  # This stage sets up the previously installed package `doas`, a sudo replacement.
  # We configure it so that the user `ubuntu` can execute root commands password-less.
  echo "permit nopass ${USER}" >/etc/doas.conf
  chown root:root /etc/doas.conf
  chmod 0400 /etc/doas.conf
  doas -C /etc/doas.conf
  ln -s "$(command -v doas)" /usr/local/bin/sudo

  # We prepare hermes (https://github.com/georglauterbach/hermes) here to easily
  # set up default tools and configurations.
  curl --silent --show-error --fail --location --output /usr/local/bin/hermes \
    "https://github.com/georglauterbach/hermes/releases/download/${HERMES_VERSION}/hermes-${HERMES_VERSION}-$(uname -m)-unknown-linux-musl"
  chmod +x /usr/local/bin/hermes

  # We also update the locales. We want en_US.UTF-8 to be the standard locale.
  curl --silent --show-error --fail --location --output /usr/local/bin/update_locales.sh \
    "https://raw.githubusercontent.com/georglauterbach/hermes/refs/tags/${HERMES_VERSION}/misc/setup_locales.sh"
  chmod +x /usr/local/bin/update_locales.sh
  update_locales.sh 'en_US.UTF-8'
EOM

# We switch to the user `${USER}` and set `${HOME}` as the new working directory.
USER "${USER}"
WORKDIR "${HOME}"

RUN <<EOM
#! /usr/bin/env -S bash -o pipefail -eE -u
  shopt -s inherit_errexit

  hermes --verbose --non-interactive
  doas apt-get --yes clean
  doas rm -rf /var/lib/apt/lists/* /tmp/*

  # The following directories are likely mount points, and need correct ownership.
  mkdir -p '.vscode-server/extensions' '.cache'
EOM

# Finally, we add metadata to the image.
LABEL org.opencontainers.image.title="Custom Development Container Base Image"
LABEL org.opencontainers.image.vendor="Georg Lauterbach (@georglauterbach) on GitHub"
LABEL org.opencontainers.image.authors="Georg Lauterbach (@georglauterbach)"
LABEL org.opencontainers.image.licenses="MIT"
LABEL org.opencontainers.image.description="A custom Development Container base image packed with as much as necessary and as few as possible configurations and applications to make development a breeze."
LABEL org.opencontainers.image.url="https://github.com/georglauterbach/dev-container-base"
LABEL org.opencontainers.image.documentation="https://github.com/georglauterbach/dev-container-base/blob/main/README.md"
LABEL org.opencontainers.image.source="https://github.com/georglauterbach/dev-container-base/blob/main/Dockerfile"

# ARG invalidates the build cache when it is used by a layer (implicitly affects RUN).
# Thus, to maximize cache, keep these lines last.
ARG VCS_RELEASE=edge
ARG VCS_REVISION=unknown

# This variable can be used to determine whether you are inside a Development
# Container. If it set, you are inside a Development Container that uses this
# image as a base. It contains the version of this image and the version
# control system revision, separated by a dash.
ENV DEV_CONTAINER_BASE_VERSION=${VCS_RELEASE}#${VCS_REVISION}

# Finally, we provide the version information for this image.
LABEL org.opencontainers.image.version=${VCS_RELEASE}
LABEL org.opencontainers.image.revision=${VCS_REVISION}