anchor.diff:      TERM=xterm
   
   RUN set -x \
  +# Install prerequisites
   	&& apt-get update \
   	&& DEBIAN_FRONTEND=noninteractive apt-get install --no-install-recommends --no-install-suggests -y \
         apt-transport-https \
  
positive.code: 		APT_KEY_DONT_WARN_ON_DANGEROUS_USAGE="True" apt-key adv --keyserver "$server" --keyserver-options timeout=10 --recv-keys "$GPGKEY" && found=yes && break; \
  	done; \
  	test -z "$found" && echo >&2 "error: failed to fetch GPG key $GPGKEY" && exit 1; \
    apt-get remove --purge --auto-remove -y gnupg && apt-get clean && rm -rf /var/lib/apt/lists/*
  
  # Add the official torproject.org Debian Tor repository
  # - this will always install the latest stable version
  COPY ./config/tor-apt-sources.list /etc/apt/sources.list.d/
  
  # Install:
  # - install tor and obfs4proxy
  # - backup torrc
  RUN apt-get update && \
      DEBIAN_FRONTEND=noninteractive apt-get install --no-install-recommends --no-install-suggests -y \
        tor \
        deb.torproject.org-keyring \
        obfs4proxy && \
      mv -v /etc/tor/torrc /etc/tor/torrc.default && \
      apt-get clean && rm -rf /var/lib/apt/lists/*
  
  # Copy Tor configuration file
  COPY ./config/torrc /etc/tor/torrc
  
negative.code: # Dockerfile for Tor Relay Server with obfs4proxy
  #
  # TODO:
  # - add GeoIP
  