feat: execute service as distributed erlang (#96)

To create a cluster with distributed nodes, the following changes were made:

* Use [`dns_cluster`][0] to execute distributed nodes
* Add _script_ to execute distributed nodes locally

Also, improve local execution by:

* Use [`mix release`][1] to make easier [deploy `phoenix`][2]
* Use [`compose watch`][3] to synchronize code from the host with the service

Some minor improvements:

* Ignore files and folders in git and docker
* Remove boilerplate comments

[0]: https://github.com/phoenixframework/dns_cluster
[1]: https://hexdocs.pm/mix/Mix.Tasks.Release.html
[2]: https://hexdocs.pm/phoenix/releases.html
[3]: https://docs.docker.com/compose/how-tos/file-watch/

Co-authored-by: Joao P Dubas <joao.dubas@gmail.com>
Reviewed-on: #96
Co-authored-by: Joao P Dubas <joao.dubas+gitea@gmail.com>
Co-committed-by: Joao P Dubas <joao.dubas+gitea@gmail.com>

Dockerfile

@@ -1,10 +1,70 @@
-FROM hexpm/elixir:1.17.2-erlang-27.0.1-debian-bookworm-20240701-slim AS builder
+ARG ELIXIR_VERSION=1.17.3
+ARG OTP_VERSION=27.1
+ARG DEBIAN_VERSION=bookworm-20240904-slim
+ARG BUILDER_IMAGE="hexpm/elixir:${ELIXIR_VERSION}-erlang-${OTP_VERSION}-debian-${DEBIAN_VERSION}"
+ARG RUNNER_IMAGE="debian:${DEBIAN_VERSION}"
 
+FROM ${BUILDER_IMAGE} AS builder
 RUN apt-get update \
-  && apt-get -y install git make
-
+  && apt-get -y install \
+    build-essential \
+    git \
+    make \
+  && apt-get clean \
+  && rm -rf /var/lib/ap/lists/*_*
 WORKDIR /opt/app
+# install hex + rebar
+RUN mix do local.hex --force, local.rebar --force
+# set build ENV
+ARG BUILD_MIX_ENV=prod
+ENV MIX_ENV=${BUILD_MIX_ENV}
+# install mix dependencies
+COPY mix.exs mix.lock ./
+RUN mix deps.get --only ${MIX_ENV}
+RUN mkdir config
+# copy compile-time config files before we compile dependencies
+# to ensure any relevant config change will trigger the dependencies
+# to be re-compiled.
+COPY config/config.exs config/${BUILD_MIX_ENV}.exs config/
+RUN mix deps.compile
+COPY priv priv
+COPY lib lib
+# Compile the release
+RUN mix compile
+# Changes to config/runtime.exs don't require recompiling the code
+COPY config/runtime.exs config/
+COPY rel rel
+RUN mix release
 COPY ./mix.exs ./
-COPY ./mix.lock ./
-RUN mix do local.hex --force, local.rebar --force \
-  && mix do deps.get, deps.compile
+EXPOSE 4000
+ENTRYPOINT ["./priv/docker/service/docker-entrypoint.sh"]
+CMD ["sample-cookie"]
+
+# start a new build stage so that the final image will only contain
+# the compiled release and other runtime necessities
+FROM ${RUNNER_IMAGE}
+RUN apt-get update -y \
+  && apt-get install -y \
+    ca-certificates \
+    libncurses5 \
+    libstdc++6 \
+    locales \
+    openssl \
+    tini \
+  && apt-get clean && rm -f /var/lib/apt/lists/*_*
+# Set the locale
+RUN sed -i '/en_US.UTF-8/s/^# //g' /etc/locale.gen && locale-gen
+ENV LANG en_US.UTF-8
+ENV LANGUAGE en_US:en
+ENV LC_ALL en_US.UTF-8
+WORKDIR /opt/app
+RUN chown nobody /opt/app
+# set runner ENV
+ARG BUILD_MIX_ENV=prod
+ENV MIX_ENV=${BUILD_MIX_ENV}
+# Only copy the final release from the build stage
+COPY --from=builder --chown=nobody:root /app/_build/${BUILD_MIX_ENV}/rel/wabanex ./
+USER nobody
+EXPOSE 4000
+ENTRYPOINT ["tini", "--"]
+CMD ["/app/bin/server"]