[mc] Putting back usermod solution

minecraft-server/Dockerfile

@@ -5,7 +5,7 @@ MAINTAINER itzg
 ENV APT_GET_UPDATE 2015-10-03
 RUN apt-get update
 
-RUN DEBIAN_FRONTEND=noninteractive apt-get install -y libmozjs-24-bin imagemagick lsof && apt-get clean
+RUN DEBIAN_FRONTEND=noninteractive apt-get install -y libmozjs-24-bin imagemagick lsof sudo && apt-get clean
 RUN update-alternatives --install /usr/bin/js js /usr/bin/js24 100
 
 RUN wget -O /usr/bin/jsawk https://github.com/micha/jsawk/raw/master/jsawk
@@ -19,6 +19,7 @@ RUN useradd -M -s /bin/false --uid 1000 minecraft \
 
 EXPOSE 25565
 
+COPY start.sh /start
 COPY start-minecraft.sh /start-minecraft
 
 VOLUME ["/data"]
@@ -28,8 +29,7 @@ VOLUME ["/plugins"]
 COPY server.properties /tmp/server.properties
 WORKDIR /data
 
-USER minecraft
+CMD [ "/start" ]
-CMD [ "/start-minecraft" ]
 
 # Special marker ENV used by MCCY management tool
 ENV MC_IMAGE=YES

minecraft-server/start.sh

@@ -0,0 +1,15 @@
+#!/bin/sh
+
+set -e
+usermod --uid $UID minecraft
+groupmod --gid $GID minecraft
+
+chown -R minecraft:minecraft /data /start-minecraft
+chmod -R g+wX /data /start-minecraft
+
+while lsof -- /start-minecraft; do
+  echo -n "."
+  sleep 1
+done
+echo "...switching to user 'minecraft'"
+exec sudo -E -u minecraft /start-minecraft