Refactor dockerfile to minimize image size

Dockerfile

@@ -1,21 +1,44 @@
-FROM debian:unstable-slim as builder_source
+FROM debian:unstable-slim as base
+
 RUN apt-get update && apt-get install -y \
   && apt-get install -y git build-essential pkg-config libssl-dev libpcre2-dev libargon2-0-dev libsodium-dev libc-ares-dev libcurl4-openssl-dev \
-  && rm -rf /var/lib/apt/lists/*
-
-WORKDIR /opt
-RUN git clone https://github.com/unrealircd/unrealircd.git --depth 1 . \
-  && ./configure --with-showlistmodes --enable-ssl --with-bindir=/app/bin --with-datadir=/app/data --with-pidfile=/app/data/unrealircd.pid --with-confdir=/app/conf --with-modulesdir=/app/modules --with-logdir=/app/logs --with-cachedir=/app/cache --with-docdir=/app/doc --with-tmpdir=/app/tmp --with-privatelibdir=/app/lib --with-scriptdir=/app --with-nick-history=2000 --with-permissions=0600 --enable-dynamic-linking \
+  && mkdir /opt/unrealircd \
+  && cd /opt/unrealircd \
+  && git clone https://github.com/unrealircd/unrealircd.git --depth 1 . \
+  && ./configure \
+     --with-showlistmodes \
+     --enable-ssl \
+     --with-bindir=/app/bin \
+     --with-datadir=/app/data \
+     --with-pidfile=/app/data/unrealircd.pid \
+     --with-confdir=/app/conf \
+     --with-modulesdir=/app/modules \
+     --with-logdir=/app/logs \
+     --with-cachedir=/app/cache \
+     --with-docdir=/app/doc \
+     --with-tmpdir=/app/tmp \
+     --with-privatelibdir=/app/lib \
+     --with-scriptdir=/app \
+     --with-nick-history=2000 \
+     --with-permissions=0600 \
+     --enable-dynamic-linking \
   && make -j4 \
   && make install \
   && rm /app/source \
-  && cp /app/conf/examples/example.conf /app/conf/unrealircd.conf
+  && cp /app/conf/examples/example.conf /app/conf/unrealircd.conf \
+  && rm -rf /opt/unrealircd \
+  && cd /app \
+  && useradd unrealircd \
+  && chown unrealircd:unrealircd -R /app \
+  && ldd /app/bin/unrealircd | tr -s '[:blank:]' '\n' | grep '^/' | xargs -I % sh -c 'mkdir -p $(dirname /app/deps%); cp % /app/deps%;' \
+  && apt purge --yes git build-essential pkg-config libssl-dev libpcre2-dev libargon2-0-dev libsodium-dev libc-ares-dev libcurl4-openssl-dev \
+  && apt autoremove --yes --purge \
+  && cp -r /app/deps/* / \
+  && rm -rf /var/lib/apt/lists/*
+
+USER unrealircd
 
-FROM builder_source AS builder_binary
-COPY --from=builder_source /app /app
-WORKDIR /app
-RUN useradd unrealircd \
-  && chown unrealircd:unrealircd -R /app
-  USER unrealircd
 CMD /app/unrealircd start \
   && until ! [ -f /app/data/unrealircd.pid ]; do sleep 60; done
+
+EXPOSE 6900 6697 6667