anchor.diff:      && make install
   
   
  -RUN curl -SLO "https://github.com/varnish/libvmod-digest/archive/libvmod-digest-$VMOD_DIGEST_VERSION.tar.gz" \
  -    && mkdir -p /usr/local/libvmod-digest \
  -    && tar -xzvf "libvmod-digest-$VMOD_DIGEST_VERSION.tar.gz" -C /usr/local/libvmod-digest --strip-components=1 \
  -    && cd /usr/local/libvmod-digest \
  -    && ./autogen.sh \
  -    && ./configure VARNISHSRC=/usr/src/varnish-cache/ \
  -    && make \
  -    && make install
  -
  -RUN curl -SLO "https://github.com/varnish/varnish-modules/archive/varnish-modules-$VMOD_MODULES_VERSION.tar.gz" \
  +RUN curl -SLO "https://github.com/varnish/varnish-modules/archive/$VMOD_MODULES_VERSION.tar.gz" \
       && mkdir -p /usr/local/varnish-modules \
  -    && tar -xzvf "varnish-modules-$VMOD_MODULES_VERSION.tar.gz" -C /usr/local/varnish-modules --strip-components=1 \
  +    && tar -xzvf "$VMOD_MODULES_VERSION.tar.gz" -C /usr/local/varnish-modules --strip-components=1 \
       && cd /usr/local/varnish-modules \
       && ./bootstrap \
  -    && ./configure VARNISHSRC=/usr/src/varnish-cache/ \
  -    && make \
  -    && make install
  -
  -RUN mkdir -p /usr/local/libvmod-geoip \
  -    && git clone https://github.com/asvinours/libvmod-geoip.git /usr/local/libvmod-geoip \
  -    && cd /usr/local/libvmod-geoip \
  -    && ./autogen.sh \
       && ./configure VARNISHSRC=/usr/src/varnish-cache/ \
       && make \
       && make install
  
positive.code: FROM debian:jessie
  
  # References
  # https://www.varnish-cache.org/docs/3.0/installation/install.html#configuring-and-compiling
  # http://blog.tenya.me/blog/2013/10/25/geoip-with-varnish/
  
  RUN apt-get update && apt-get install -y \
          apt-transport-https \
  
negative.code:         tar
  
  ENV VARNISH_VERSION 4.1.4
  ENV VMOD_MODULES_VERSION 0.11.0
  
  RUN curl -SLO "https://github.com/varnishcache/varnish-cache/archive/varnish-$VARNISH_VERSION.tar.gz" \
      && mkdir -p /usr/local/varnish-cache \
  