refactor: Dockerfile (includes OTP update) (#41)

Dockerfile

@@ -1,14 +1,29 @@
-FROM erlang:21-alpine AS build
+FROM hexpm/erlang:25.3.2.3-alpine-3.18.2 AS erlang
 
-WORKDIR /root
+WORKDIR /app
+ENV REBAR_VERSION=3.22.0
 
-ADD . /root
+FROM erlang AS downloader
 
-RUN rebar3 escriptize
+RUN apk --no-cache add curl; \
+    mkdir -p /tmp/tools; \
+    curl -L https://github.com/erlang/rebar3/releases/download/${REBAR_VERSION}/rebar3 > /tmp/tools/rebar3; \
+    chmod +x /tmp/tools/*
 
-FROM erlang:21-alpine
+FROM erlang AS build
 
-COPY --from=build /root/_build/default/bin/erlang_analyzer /opt/analyzer/bin/erlang_analyzer
-COPY              _docker/analyze.sh                       /opt/analyzer/bin/analyze.sh
+COPY --from=downloader /tmp/tools/rebar3 rebar3
+COPY rebar.config rebar.lock ./
+
+RUN ./rebar3 get-deps
+
+COPY src/ src/
+
+RUN ./rebar3 escriptize
+
+FROM erlang
+
+COPY --from=build /app/_build/default/bin/erlang_analyzer /opt/analyzer/bin/erlang_analyzer
+COPY              _docker/analyze.sh                      /opt/analyzer/bin/analyze.sh
 
 ENTRYPOINT ["/opt/analyzer/bin/analyze.sh"]