Dockerfile

FROM elixir:1.10.2

# NOTE the WORKDIR should not be the users home dir as the will copy container cookie into host machine
WORKDIR /opt/app

RUN curl -sL https://deb.nodesource.com/setup_12.x | bash -
# Add tools needed for development
# inotify-tools: gives filesystem events that are used to trigger recompilation
RUN apt-get update && apt-get install -y inotify-tools nodejs

ENV MIX_ARTIFACTS_DIRECTORY=../mix_artifacts

RUN mix local.hex --force && mix local.rebar --force && \
    mkdir -p ${MIX_ARTIFACTS_DIRECTORY}/deps && mkdir -p ${MIX_ARTIFACTS_DIRECTORY}/_build && \
    mkdir config

# Build all dependencies separately to the application code
COPY mix.* ./
RUN mix do deps.get
COPY config/* config/
RUN mix deps.compile && MIX_ENV=test mix deps.compile

# Add application code as final layer
# This will skip the _build and deps directories as per .dockerignore
COPY . .

# Make sure the Docker image can be started without waiting for the project to compile
# NOTE: mix deps.get is needed to update the freshly copied mix.lock file
RUN mix do deps.get
# Can't do compile at build stage because the SECRET_KEY_BASE for sessions is read at compile time
# RUN mix do deps.get, compile

CMD ["sh", "./bin/start.sh"]