Use http replicator as http proxy for docker build

proxy.sh

#!/bin/sh

CACHE_DIR=cache
mkdir -p $CACHE_DIR
http-replicator -p 8080 -i *.*.*.* -d $CACHE_DIR -s --daemon --log $CACHE_DIR/replicator.log

# add e.g. `ENV http_proxy http://172.17.42.1:8080` to your Dockerfile