add docker release

Dockerfile

@@ -0,0 +1,94 @@
+# Find eligible builder and runner images on Docker Hub. We use Ubuntu/Debian
+# instead of Alpine to avoid DNS resolution issues in production.
+#
+# https://hub.docker.com/r/hexpm/elixir/tags?name=ubuntu
+# https://hub.docker.com/_/ubuntu/tags
+#
+# This file is based on these images:
+#
+#   - https://hub.docker.com/r/hexpm/elixir/tags - for the build image
+#   - https://hub.docker.com/_/debian/tags?name=trixie-20260112-slim - for the release image
+#   - https://pkgs.org/ - resource for finding needed packages
+#   - Ex: docker.io/hexpm/elixir:1.16.2-erlang-26.1.1-debian-trixie-20260112-slim
+#
+ARG ELIXIR_VERSION=1.16.2
+ARG OTP_VERSION=26.1.1
+ARG DEBIAN_VERSION=trixie-20260112-slim
+
+ARG BUILDER_IMAGE="docker.io/hexpm/elixir:${ELIXIR_VERSION}-erlang-${OTP_VERSION}-debian-${DEBIAN_VERSION}"
+ARG RUNNER_IMAGE="docker.io/debian:${DEBIAN_VERSION}"
+
+FROM ${BUILDER_IMAGE} AS builder
+
+# install build dependencies
+RUN apt-get update \
+  && apt-get install -y --no-install-recommends build-essential git \
+  && rm -rf /var/lib/apt/lists/*
+
+# prepare build dir
+WORKDIR /app
+
+# install hex + rebar
+RUN mix local.hex --force \
+  && mix local.rebar --force
+
+# set build ENV
+ENV MIX_ENV="prod"
+
+# install mix dependencies
+COPY mix.exs mix.lock ./
+RUN mix deps.get --only $MIX_ENV
+RUN mkdir config
+
+# copy compile-time config files before we compile dependencies
+# to ensure any relevant config change will trigger the dependencies
+# to be re-compiled.
+COPY config/config.exs config/${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
+
+# start a new build stage so that the final image will only contain
+# the compiled release and other runtime necessities
+FROM ${RUNNER_IMAGE} AS final
+
+RUN apt-get update \
+  && apt-get install -y --no-install-recommends libstdc++6 openssl libncurses6 locales ca-certificates \
+  && rm -rf /var/lib/apt/lists/*
+
+# Set the locale
+RUN sed -i '/en_US.UTF-8/s/^# //g' /etc/locale.gen \
+  && locale-gen
+
+ENV LANG=en_US.UTF-8
+ENV LANGUAGE=en_US:en
+ENV LC_ALL=en_US.UTF-8
+
+WORKDIR "/app"
+RUN chown nobody /app
+
+# set runner ENV
+ENV MIX_ENV="prod"
+
+# Only copy the final release from the build stage
+COPY --from=builder --chown=nobody:root /app/_build/${MIX_ENV}/rel/camp_api ./
+
+USER nobody
+
+# If using an environment that doesn't automatically reap zombie processes, it is
+# advised to add an init process such as tini via `apt-get install`
+# above and adding an entrypoint. See https://github.com/krallin/tini for details
+# ENTRYPOINT ["/tini", "--"]
+
+CMD ["/app/bin/server"]