anchor.diff:  # install tini
   RUN \
   	TINI_VERSION=v0.18.0 && \
  -	http_proxy='' gpg --keyserver ipv4.pool.sks-keyservers.net --recv-keys 0527A9B7 && \
  +	for server in $(shuf -e ${GPG_SERVERS}) ; do \
  +		http_proxy= gpg --keyserver "$server" --recv-keys 0527A9B7 && break || : ; \
  +	done && \
   	wget -O/usr/bin/tini     "https://github.com/krallin/tini/releases/download/${TINI_VERSION}/tini" && \
   	wget -O/usr/bin/tini.asc "https://github.com/krallin/tini/releases/download/${TINI_VERSION}/tini.asc" && \
   	gpg --verify /usr/bin/tini.asc && \
  
positive.code: 	LC_ALL=C.UTF-8 \
  	LANG=C.UTF-8 \
  	LANGUAGE=C.UTF-8 \
  	DEBIAN_FRONTEND=noninteractive
  
  # add runtime user
  RUN \
  
negative.code: # install gosu
  RUN \
  	GOSU_VERSION=1.11 && \
  	for server in $(shuf -e ${GPG_SERVERS}); do \
  		http_proxy= gpg --keyserver "$server" --recv-keys B42F6819007F00F88E364FD4036A9C25BF357DD4 && break || : ; \
  	done && \
  	wget -O/usr/bin/gosu     "https://github.com/tianon/gosu/releases/download/${GOSU_VERSION}/gosu-amd64" && \
  	wget -O/usr/bin/gosu.asc "https://github.com/tianon/gosu/releases/download/${GOSU_VERSION}/gosu-amd64.asc" && \
  	gpg --verify /usr/bin/gosu.asc && \
  