Run container as tor user

Dockerfile

@@ -13,5 +13,7 @@ EXPOSE 9050/tcp
 HEALTHCHECK --interval=5m --timeout=5s \
   CMD timeout 2 curl -sfo /dev/null --socks5-hostname 127.0.0.1:9050 'https://check.torproject.org'
 
+USER tor
+
 ENTRYPOINT ["/usr/bin/tor"]
 CMD ["-f", "/etc/tor/torrc"]