Dockerfile: bundle rTorrent (not started by default) in master-dbg image

Dockerfile

@@ -2,6 +2,10 @@
 #
 # For development and debugging only. Use Dockerfile.release for production.
 #
+# This image bundles rTorrent for easier debugging. It is not started by default.
+# Use --rtorrent argument if you wish to start the bundled rTorrent.
+# For production, use rtorrent-flood instead.
+#
 # This Dockerfile uses contents of current folder which might contain
 # secrets, uncommitted changes or other sensitive information. DO NOT
 # publish the result image unless it was composed in a clean environment.
@@ -9,6 +13,8 @@
 ARG BUILDPLATFORM=amd64
 ARG NODE_IMAGE=node:alpine
 
+FROM jesec/rtorrent:master as rtorrent
+
 FROM --platform=$BUILDPLATFORM ${NODE_IMAGE} as nodebuild
 
 WORKDIR /usr/src/app/
@@ -31,6 +37,9 @@ WORKDIR /usr/src/app/
 # Copy sources
 COPY --from=nodebuild /usr/src/app ./
 
+# Copy rTorrent
+COPY --from=rtorrent / /
+
 # Install runtime dependencies
 RUN apk --no-cache add \
     mediainfo