Assuming /etc/default/lxc is sourced, how about integrating this directly in it:
# Is there a local apt-proxy/cacher available ? eval $(apt-config shell MIRROR Acquire::http::Proxy)
Assuming /etc/default/lxc is sourced, how about integrating this directly in it:
# Is there a local apt-proxy/cacher available ? :http:: Proxy)
eval $(apt-config shell MIRROR Acquire: