speed up docker build

Author: dylhack

railties/lib/rails/generators/rails/app/templates/Dockerfile.tt

@@ -103,16 +103,15 @@ RUN rm -rf node_modules
 # Final stage for app image
 FROM base
 
-# Copy built artifacts: gems, application
-COPY --from=build "${BUNDLE_PATH}" "${BUNDLE_PATH}"
-COPY --from=build /rails /rails
-
 # Run and own only the runtime files as a non-root user for security
 RUN groupadd --system --gid 1000 rails && \
-    useradd rails --uid 1000 --gid 1000 --create-home --shell /bin/bash && \
-    chown -R rails:rails <%= dockerfile_chown_directories.join(" ") %>
+    useradd rails --uid 1000 --gid 1000 --create-home --shell /bin/bash
 USER 1000:1000
 
+# Copy built artifacts: gems, application
+COPY --chown=rails:rails --from=build "${BUNDLE_PATH}" "${BUNDLE_PATH}"
+COPY --chown=rails:rails --from=build /rails /rails
+
 # Entrypoint prepares the database.
 ENTRYPOINT ["/rails/bin/docker-entrypoint"]