Elixir Phoenix Umbrella App + Distillery Multistage Docker Build

Dockerfile

FROM elixir:1.4.5 as asset-builder-mix-getter

ENV HOME=/opt/app

RUN mix do local.hex --force, local.rebar --force
# Cache elixir deps
COPY config/ $HOME/config/
COPY mix.exs mix.lock $HOME/
COPY apps/myproject_web/mix.exs $HOME/apps/myproject_web/
COPY apps/myproject_web/config/ $HOME/apps/myproject_web/config/

WORKDIR $HOME/apps/myproject_web
RUN mix deps.get

########################################################################
FROM node:6 as asset-builder

ENV HOME=/opt/app
WORKDIR $HOME

COPY --from=asset-builder-mix-getter $HOME/deps $HOME/deps

WORKDIR $HOME/apps/myproject_web/assets
COPY apps/myproject_web/assets/ ./
RUN yarn install
RUN ./node_modules/.bin/brunch build --production

########################################################################
FROM bitwalker/alpine-elixir:1.4.5 as releaser

ENV HOME=/opt/app

ARG ERLANG_COOKIE
ENV ERLANG_COOKIE $ERLANG_COOKIE

# dependencies for comeonin
RUN apk add --no-cache build-base cmake

# Install Hex + Rebar
RUN mix do local.hex --force, local.rebar --force

# Cache elixir deps
COPY config/ $HOME/config/
COPY mix.exs mix.lock $HOME/

# Copy umbrella app config + mix.exs files
COPY apps/myproject/mix.exs $HOME/apps/myproject/
COPY apps/myproject/config/ $HOME/apps/myproject/config/

COPY apps/myproject_web/mix.exs $HOME/apps/myproject_web/
COPY apps/myproject_web/config/ $HOME/apps/myproject_web/config/

ENV MIX_ENV=prod
RUN mix do deps.get --only $MIX_ENV, deps.compile

COPY . $HOME/

# Digest precompiled assets
COPY --from=asset-builder $HOME/apps/myproject_web/priv/static/ $HOME/apps/myproject_web/priv/static/

WORKDIR $HOME/apps/myproject_web
RUN mix phx.digest

# Release
WORKDIR $HOME
RUN mix release --env=$MIX_ENV --verbose

########################################################################
FROM alpine:3.6

ENV LANG=en_US.UTF-8 \
    HOME=/opt/app/ \
    TERM=xterm

ENV MYPROJECT_VERSION=0.1.0

RUN apk add --no-cache ncurses-libs openssl

EXPOSE 4000
ENV PORT=4000 \
    MIX_ENV=prod \
    REPLACE_OS_VARS=true \
    SHELL=/bin/sh

COPY --from=releaser $HOME/_build/prod/rel/myproject/releases/$MYPROJECT_VERSION/myproject.tar.gz $HOME
WORKDIR $HOME
RUN tar -xzf myproject.tar.gz

ENTRYPOINT ["/opt/app/bin/myproject"]
CMD ["foreground"]

thanks for sharing this. used it as a basis for my own Dockerfile for Elixir umbrella app.

I have a question, why did you copy over the config files before running RUN mix do deps.get --only $MIX_ENV, deps.compile? Just curious because I tried it without copying over the config and everything worked fine.

I have a question, why did you copy over the config files before running RUN mix do deps.get --only $MIX_ENV, deps.compile? Just curious because I tried it without copying over the config and everything worked fine.

It allows you to cache the dependencies of your project and not rebuild them every single time your code change.