Docker: run as parity user (#9689)

scripts/docker/hub/Dockerfile

@@ -15,8 +15,17 @@ RUN apt autoremove -y
 RUN apt clean -y
 RUN rm -rf /tmp/* /var/tmp/* /var/lib/apt/lists/*
 
+RUN groupadd -g 1000 parity \
+  && useradd -m -u 1000 -g parity -s /bin/sh parity
+
+USER parity
+
+WORKDIR /home/parity
+
+ENV PATH "~/bin:${PATH}"
+
 #add TARGET to docker image
-COPY artifacts/x86_64-unknown-linux-gnu/$TARGET /usr/bin/$TARGET
+COPY artifacts/x86_64-unknown-linux-gnu/$TARGET ./bin/$TARGET
 
 # Build a shell script because the ENTRYPOINT command doesn't like using ENV
 RUN echo "#!/bin/bash \n ${TARGET} \$@" > ./entrypoint.sh