elixir + phoenix + node dockerfile

Dockerfile

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# 1. Build nodejs frontend
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FROM node:10.9-alpine as build-node

# prepare build dir
RUN mkdir -p /app/assets
WORKDIR /app

# set build ENV
ENV NODE_ENV=prod

# install npm dependencies
COPY assets/package.json assets/package-lock.json ./assets/
COPY deps/phoenix deps/phoenix
COPY deps/phoenix_html deps/phoenix_html
RUN cd assets && npm install

# build assets
COPY assets ./assets/
RUN cd assets && npm run deploy


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# 2. Build elixir backend
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FROM elixir:1.6.6-alpine as build-elixir

# install build dependencies
RUN apk add --update git

# prepare build dir
RUN mkdir /app
WORKDIR /app

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

# set build ENV
ENV MIX_ENV=prod

# install dependencies
COPY mix.exs mix.lock ./
RUN mix deps.get

# compile dependencies
COPY config ./config/
RUN mix deps.compile

# copy only elixir files to keep the cache
COPY lib ./lib/
COPY priv ./priv/
COPY rel ./rel/

# copy assets from node build
COPY --from=build-node /app/priv/static ./priv/static
RUN mix phx.digest

# build release
RUN mix release --no-tar --verbose


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# 3. Build release image
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FROM alpine:3.8
RUN apk add --update bash openssl

RUN mkdir /app && chown -R nobody: /app
WORKDIR /app
USER nobody

COPY --from=build-elixir /app/_build/prod/rel/myapp ./

ARG VERSION
ENV VERSION=$VERSION
ENV REPLACE_OS_VARS=true
EXPOSE 4000

ENTRYPOINT ["/app/bin/myapp"]
CMD ["foreground"]