Improve Dockerfile

Dockerfile

@@ -1,11 +1,20 @@
 FROM docker.io/eclipse-temurin:21
+
 RUN apt-get update \
     && apt-get install -y ffmpeg \
     && apt-get clean \
     && rm -rf /var/lib/apt/lists/*
-RUN groupadd -r spring && useradd --no-log-init -r -g spring spring
-USER spring:spring
+
+RUN groupadd --system app \
+    && useradd --no-log-init --system --shell /sbin/nologin --gid app app
+
+WORKDIR /app
+
 ARG JAR_FILE=build/libs/*.jar
-COPY ${JAR_FILE} app.jar
-COPY build/resources/main/static BOOT-INF/classes/static
-ENTRYPOINT ["java","-jar","/app.jar"]
+COPY --chown=app:app ${JAR_FILE} app.jar
+COPY --chown=app:app build/resources/main/static BOOT-INF/classes/static
+
+USER app:app
+
+ENTRYPOINT ["java","-jar","app.jar"]
+