dockerfile

ARG ELIXIR_VERSION=1.13.4
ARG OTP_VERSION=25.0.3
ARG DEBIAN_VERSION=bullseye-20210902-slim

ARG BUILDER_IMAGE="hexpm/elixir:${ELIXIR_VERSION}-erlang-${OTP_VERSION}-debian-${DEBIAN_VERSION}"
ARG RUNNER_IMAGE="debian:${DEBIAN_VERSION}"

FROM ${BUILDER_IMAGE} as builder

# install build dependencies
RUN apt-get update -y && apt-get install -y build-essential git \
    && apt-get clean && rm -f /var/lib/apt/lists/*_*

# prepare build dir
WORKDIR /app

# install hex + rebar
RUN mix local.hex --force && \
    mix local.rebar --force

# set build ENV
ENV MIX_ENV="prod"

# install mix dependencies
COPY mix.exs mix.lock ./

ENV NOTESCLUB_IS_OBAN_WEB_PRO_ENABLED="true"

RUN --mount=type=secret,id=OBAN_KEY_FINGERPRINT \
  --mount=type=secret,id=OBAN_LICENSE_KEY \
  mix hex.repo add oban https://getoban.pro/repo \
  --fetch-public-key "$(cat /run/secrets/OBAN_KEY_FINGERPRINT)" \
  --auth-key "$(cat /run/secrets/OBAN_LICENSE_KEY)"

RUN mix deps.get --only $MIX_ENV

RUN mkdir config

# copy compile-time config files before we compile dependencies
# to ensure any relevant config change will trigger the dependencies
# to be re-compiled.
COPY config/config.exs config/${MIX_ENV}.exs config/
RUN mix deps.compile

COPY priv priv

COPY lib lib

COPY assets assets

# compile assets
RUN mix assets.deploy

# Compile the release
RUN mix compile

# Changes to config/runtime.exs don't require recompiling the code
COPY config/runtime.exs config/

COPY rel rel
RUN mix release

# start a new build stage so that the final image will only contain
# the compiled release and other runtime necessities
FROM ${RUNNER_IMAGE}

RUN apt-get update -y && apt-get install -y libstdc++6 openssl libncurses5 locales \
  && apt-get clean && rm -f /var/lib/apt/lists/*_*

# Set the locale
RUN sed -i '/en_US.UTF-8/s/^# //g' /etc/locale.gen && locale-gen

ENV LANG en_US.UTF-8
ENV LANGUAGE en_US:en
ENV LC_ALL en_US.UTF-8

WORKDIR "/app"
RUN chown nobody /app

# set runner ENV
ENV MIX_ENV="prod"

# Only copy the final release from the build stage
COPY --from=builder --chown=nobody:root /app/_build/${MIX_ENV}/rel/notesclub ./

USER nobody

CMD ["sh", "-c", "/app/bin/notesclub eval Notesclub.Release.migrate && exec /app/bin/server"]

The latest Dockerfile is on https://github.com/notesclub/notesclub/blob/main/Dockerfile

We install tailwind and esbuild in that step to take advantage of caching:

RUN mix do deps.compile, tailwind.install --if-missing, esbuild.install --if-missing