try diff dockerfile fmt

backend/Dockerfile

@@ -1,4 +1,17 @@
-FROM amazoncorretto:17
-ENV HOME=/app
-RUN mkdir -p $HOME
-WORKDIR $HOME
+FROM eclipse-temurin:17.0.8_7-jdk as build
+
+WORKDIR /app/
+
+ADD ./backend /app/backend
+ADD .git /app/.git
+
+# compile backend into a jar
+RUN cd backend && ./gradlew clean build -x test -x checkstyleMain -x spotlessCheck
+
+FROM eclipse-temurin:17.0.8_7-jre
+
+COPY --from=build /app/backend/build/libs/*.jar app.jar
+
+ENTRYPOINT ["java","-jar","/app.jar"]
+
+EXPOSE 8081