ARG ELIXIR_VERSION=1.18.4
ARG OTP_VERSION=27.2.4
ARG DEBIAN_VERSION=bullseye-20250520-slim

# Set default non-root user and group IDs
ARG USER_ID=1000
ARG GROUP_ID=1000

ARG BUILDER_IMAGE="hexpm/elixir:${ELIXIR_VERSION}-erlang-${OTP_VERSION}-debian-${DEBIAN_VERSION}"
# Use distroless base image with glibc for Erlang/Elixir
ARG RUNNER_IMAGE="gcr.io/distroless/base-debian11:nonroot"

FROM ${BUILDER_IMAGE} AS builder

# install build dependencies
RUN apt-get update -y && \
    apt-get upgrade -y && \
    apt-get install -y build-essential git && \
    apt-get clean && \
    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

COPY assets assets

# compile assets
RUN mix assets.deploy

# 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

# Create a temporary stage to prepare required libraries
FROM debian:bullseye-slim AS lib-extractor

# Install packages needed to extract libraries
RUN apt-get update -y && \
    apt-get install -y --no-install-recommends \
    libstdc++6 \
    openssl \
    libncurses5 \
    libssl1.1 \
    libtinfo5 \
    libcrypto++6 \
    ca-certificates \
    && apt-get clean && \
    rm -rf /var/lib/apt/lists/*

# Create directories for extracted libraries
RUN mkdir -p /tmp/distroless/lib /tmp/distroless/usr/lib /tmp/distroless/etc/ssl /tmp/distroless/usr/share

# Copy required shared libraries
RUN cp -a /lib/x86_64-linux-gnu/libdl.so* /tmp/distroless/lib/ && \
    cp -a /lib/x86_64-linux-gnu/librt.so* /tmp/distroless/lib/ && \
    cp -a /lib/x86_64-linux-gnu/libpthread.so* /tmp/distroless/lib/ && \
    cp -a /lib/x86_64-linux-gnu/libm.so* /tmp/distroless/lib/ && \
    cp -a /lib/x86_64-linux-gnu/libc.so* /tmp/distroless/lib/ && \
    cp -a /usr/lib/x86_64-linux-gnu/libstdc++.so* /tmp/distroless/usr/lib/ && \
    cp -a /usr/lib/x86_64-linux-gnu/libssl.so* /tmp/distroless/usr/lib/ && \
    cp -a /usr/lib/x86_64-linux-gnu/libcrypto.so* /tmp/distroless/usr/lib/ && \
    cp -a /lib/x86_64-linux-gnu/libtinfo.so* /tmp/distroless/lib/ && \
    cp -a /usr/lib/x86_64-linux-gnu/libncurses.so* /tmp/distroless/usr/lib/ && \
    cp -a /lib/x86_64-linux-gnu/libz.so* /tmp/distroless/lib/

# Copy CA certificates
RUN cp -a /etc/ssl/certs /tmp/distroless/etc/ssl/

# Final distroless stage
FROM ${RUNNER_IMAGE}

# Set environment variables for production
ENV MIX_ENV="prod" \
    LANG=C.UTF-8 \
    LANGUAGE=C:en \
    LC_ALL=C.UTF-8 \
    # Disable history files
    HISTFILE=/dev/null \
    # Prevent writing .erlang.cookie file to writable location
    HOME=/tmp \
    # Add security headers
    SECURITY_HEADERS="true" \
    # Configure Erlang VM for production
    ERL_AFLAGS="+S 1:1 +A 1 +K true -kernel shell_history enabled" \
    PHX_SERVER=true

# Copy required shared libraries from lib-extractor stage
COPY --from=lib-extractor /tmp/distroless/lib/* /lib/x86_64-linux-gnu/
COPY --from=lib-extractor /tmp/distroless/usr/lib/* /usr/lib/x86_64-linux-gnu/
COPY --from=lib-extractor /tmp/distroless/etc/ssl /etc/ssl

# Set working directory
WORKDIR /app

# Copy the Elixir release from builder stage
# The distroless nonroot user has UID 65532, so we use that
COPY --from=builder --chown=65532:65532 /app/_build/prod/rel/aprsme ./

# Create required directories with proper permissions
USER 0
RUN mkdir -p /tmp && \
    chmod 1777 /tmp && \
    chmod +x /app/bin/server
USER 65532

# Add security-related metadata
LABEL org.opencontainers.image.vendor="APRS.me" \
    org.opencontainers.image.title="APRS.me Server (Distroless)" \
    org.opencontainers.image.description="APRS.me server with distroless base for maximum security" \
    org.opencontainers.image.version="prod" \
    security.root-user="false" \
    security.distroless="true" \
    security.privileged="false" \
    security.base-image="gcr.io/distroless/base-debian11:nonroot"

# Distroless images use a different init system, no need for tini
# The application should handle graceful shutdowns internally

# Command to run the application
ENTRYPOINT ["/app/bin/server"]

# Container configuration is handled by Dokku
EXPOSE $PORT