working on switching to nonroot user

Dockerfile

 # JRE base
 FROM openjdk:11.0-jre-slim
 
+ARG user=papermc
+
 # Environment variables
 ENV MC_VERSION="latest" \
     PAPER_BUILD="latest" \
     MC_RAM="2G" \
     JAVA_OPTS="-XX:+UseG1GC -XX:+ParallelRefProcEnabled -XX:MaxGCPauseMillis=200 -XX:+UnlockExperimentalVMOptions -XX:+DisableExplicitGC -XX:+AlwaysPreTouch -XX:G1NewSizePercent=30 -XX:G1MaxNewSizePercent=40 -XX:G1HeapRegionSize=8M -XX:G1ReservePercent=20 -XX:G1HeapWastePercent=5 -XX:G1MixedGCCountTarget=4 -XX:InitiatingHeapOccupancyPercent=15 -XX:G1MixedGCLiveThresholdPercent=90 -XX:G1RSetUpdatingPauseTimePercent=5 -XX:SurvivorRatio=32 -XX:+PerfDisableSharedMem -XX:MaxTenuringThreshold=1 -Dusing.aikars.flags=https://mcflags.emc.gs -Daikars.new.flags=true"
 
-ADD papermc.sh .
-ADD backup.sh .
-ADD restore.sh .
+COPY papermc.sh .
+COPY backup.sh .
+COPY restore.sh .
 RUN apt-get update \
     && apt-get install wget curl jq webp screen cron -y \
     && rm -rf /var/lib/apt/lists/* \
     && mkdir /papermc \
-    && mkdir /backup
+    && mkdir /backup \
+    && chmod +x papermc.sh \
+    && chmod +x backup.sh \
+    && chmod +x restore.sh
+RUN chown -R ${user} /papermc
+RUN chown -R ${user} /backup
+RUN groupadd -r mcuser && adduser mcuser
+USER mcuser
 
 
 # Start script
@@ -23,6 +32,5 @@ CMD ["sh", "./papermc.sh"]
 # Container setup
 EXPOSE 25565/tcp
 EXPOSE 25565/udp
-EXPOSE 8123/tcp
 VOLUME /papermc
 VOLUME /backup