Elixir/Phoenix on Alpine Linux
This Dockerfile provides everything you need to run your Phoenix application in Docker out of the box.
It is based on my alpine-erlang image, and installs Elixir (1.11.0), Node.js (12.18.x), Hex and Rebar. It can handle compiling
your Node and Elixir dependencies as part of it's build.
Usage
NOTE: This image is intended to run in unprivileged environments, it sets the home directory to /opt/app, and makes it globally
read/writeable. If run with a random, high-index user account (say 1000001), the user can run an app, and that's about it. If run
with a user of your own creation, this doesn't apply (necessarily, you can of course implement the same behaviour yourself).
It is highly recommended that you add a USER default instruction to the end of your Dockerfile so that your app runs in a non-elevated context.
To boot straight to a prompt in the image:
$ docker run --rm -it --user=1000001 bitwalker/alpine-elixir-phoenix iex
Erlang/OTP 23 [erts-11.1.1] [source] [64-bit] [smp:3:3] [ds:3:3:10] [async-threads:1]
Interactive Elixir (1.11.0) - press Ctrl+C to exit (type h() ENTER for help)
iex(1)>
Extending for your own application:
FROM bitwalker/alpine-elixir-phoenix:latest
# Set exposed ports
EXPOSE 5000
ENV PORT=5000 MIX_ENV=prod
# Cache elixir deps
ADD mix.exs mix.lock ./
RUN mix do deps.get, deps.compile
# Same with npm deps
ADD assets/package.json assets/
RUN cd assets && \
npm install
ADD . .
# Run frontend build, compile, and digest assets
RUN cd assets/ && \
npm run deploy && \
cd - && \
mix do compile, phx.digest
USER default
CMD ["mix", "phx.server"]It is recommended when using this that you have the following in .dockerignore when running docker build:
_build
deps
assets/node_modules
test
This will keep the payload smaller and will also avoid any issues when compiling dependencies.
Multistage Docker Builds
You can also leverage docker multistage build and bitwalker/alpine-elixir to lower your image size significantly.
An example is shown below:
FROM bitwalker/alpine-elixir-phoenix:latest AS phx-builder
# Set exposed ports
ENV MIX_ENV=prod
# Cache elixir deps
ADD mix.exs mix.lock ./
RUN mix do deps.get, deps.compile
# Same with npm deps
ADD assets/package.json assets/
RUN cd assets && \
npm install
ADD . .
# Run frontend build, compile, and digest assets
RUN cd assets/ && \
npm run deploy && \
cd - && \
mix do compile, phx.digest
FROM bitwalker/alpine-elixir:latest
EXPOSE 5000
ENV PORT=5000 MIX_ENV=prod
COPY --from=phx-builder /opt/app/_build /opt/app/_build
COPY --from=phx-builder /opt/app/priv /opt/app/priv
COPY --from=phx-builder /opt/app/config /opt/app/config
COPY --from=phx-builder /opt/app/lib /opt/app/lib
COPY --from=phx-builder /opt/app/deps /opt/app/deps
COPY --from=phx-builder /opt/app/.mix /opt/app/.mix
COPY --from=phx-builder /opt/app/mix.* /opt/app/
# alternatively you can just copy the whole dir over with:
# COPY --from=phx-builder /opt/app /opt/app
# be warned, this will however copy over non-build files
USER default
CMD ["mix", "phx.server"]License
MIT