Dockerfile

# Find eligible builder and runner images on Docker Hub. We use Ubuntu/Debian instead of
# Alpine to avoid DNS resolution issues in production.
#
# https://hub.docker.com/r/hexpm/elixir/tags?page=1&name=ubuntu
# https://hub.docker.com/_/ubuntu?tab=tags
#
#
# This file is based on these images:
#
#   - https://hub.docker.com/r/hexpm/elixir/tags - for the build image
#   - https://hub.docker.com/_/debian?tab=tags&page=1&name=bullseye-20210902-slim - for the release image
#   - https://pkgs.org/ - resource for finding needed packages
#   - Ex: hexpm/elixir:1.13.2-erlang-24.1.4-debian-bullseye-20210902-slim
#
ARG BUILDER_IMAGE="hexpm/elixir:1.13.2-erlang-23.3.4.11-debian-bullseye-20210902-slim"
ARG RUNNER_IMAGE="debian:bullseye-20210902-slim"

###################
#
#   assets stage
#
###################
FROM node:lts-slim as assets

WORKDIR /app

RUN mkdir assets
COPY assets/package.json assets/package-lock.json assets/
RUN cd assets && npm ci

COPY lib lib
COPY assets assets
RUN cd assets && ls -la && npm run prod:js && npm run prod:css

###################
#
#   builder stage
#
###################
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 ./
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

RUN mix compile

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

COPY rel rel
COPY --from=assets /app/priv/static/assets priv/static/assets
RUN mix do phx.digest, release

###################
#
#   runner stage
#
###################
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

# Only copy the final release from the build stage
COPY --from=builder --chown=nobody:root /app/_build/prod/rel/planning_poker ./

USER nobody

CMD ["/app/bin/server"]