Fixed everything

Dockerfile

-FROM java:8-jre-alpine
-
-RUN adduser -h /minecraft  minecraft -D -s /bin/bash
+FROM openjdk:8-jre
 
 ADD http://mcmyadmin.com/Downloads/MCMA2_glibc26_2.zip /tmp/
 ADD http://mcmyadmin.com/Downloads/etc.zip /tmp/
@@ -9,6 +7,8 @@ RUN unzip -q /tmp/etc.zip -d /usr/local && \
     unzip -q /tmp/MCMA2_glibc26_2.zip -d /opt/mcmyadmin2 && \
     rm -rf /tmp/*
 
+RUN adduser --home /minecraft --shell /bin/bash --disabled-password --system minecraft
+
 VOLUME /minecraft
 USER minecraft
 
@@ -16,4 +16,4 @@ EXPOSE 8080
 EXPOSE 25565
 
 WORKDIR /minecraft
-ENTRYPOINT ["/opt/mcmyadmin/MCMA2_Linux_x86_64"]
+ENTRYPOINT ["/opt/mcmyadmin2/MCMA2_Linux_x86_64"]