I've released v1.0.2 of apt-cacher-ultra, a robust apt proxy cache that can continue to serve requests even if the upstream is down
Signature enhancements are dramatically reduced CPU utilization and the ability to use an upstream proxy. It also has ~3 months more of a track record of robust service in my environments (~200 client machines, most updating and 1/4 reinstalling daily). It's been living up to my reliability expectations. https://github.com/linsomniac/apt-cacher-ultra
