🐳 Reworks dockerfile from template

backend/Dockerfile

@@ -1,8 +1,27 @@
-FROM gradle:jdk17
+# DO NOT EDIT
+# source: https://ktor.io/docs/docker.html#manual
 
-WORKDIR /app
-COPY --chown=gradle:gradle . .
+# Stage 1: Cache Gradle dependencies
+FROM gradle:jdk17 AS cache
+RUN mkdir -p /home/gradle/cache_home
+ENV GRADLE_USER_HOME=/home/gradle/cache_home
+COPY build.gradle.* gradle.properties /home/gradle/app/
+COPY gradle /home/gradle/app/gradle
+WORKDIR /home/gradle/app
+RUN gradle dependencies --no-daemon
 
-RUN gradle buildFatJar
+# Stage 2: Build Application
+FROM gradle:jdk17 AS build
+COPY --from=cache /home/gradle/cache_home /home/gradle/.gradle
+COPY --chown=gradle:gradle . /home/gradle/src
+WORKDIR /home/gradle/src
+# Build the fat JAR, Gradle also supports shadow
+# and boot JAR by default.
+RUN gradle buildFatJar --no-daemon
 
-CMD ["gradle", "runFatJar"]
+# Stage 3: Create the Runtime Image
+FROM amazoncorretto:17 AS runtime
+EXPOSE 8080
+RUN mkdir /app
+COPY --from=build /home/gradle/src/build/libs/*.jar /app/antifed.jar
+ENTRYPOINT ["java","-jar","/app/antifed.jar"]