One of the deployments I have is a cluster of Raspberry Pis. I am trying to cache apt content. The cluster has one node running (only) squid 3.5.23 with an external HDD. All the nodes have an entry in apt.conf.d pointing to the squid node:
I find that the fetching of the release and index files is painfully slow. Squid seems to be caching the .deb and .udeb files and providing them once they've been downloaded but the apt update command seems particularly slow. All the Pi's are running the stretch release with some also using (Debian's) stretch-backports
Thoughts that spring to mind:
1. The Raspberry Pi foundation machines/network are overloaded.
2. IPv6 timing out and then trying IPv4 (both are enabled on the Pi)
3. Maybe APT is using HTTPS and I need to define a port for it to listen on.
Has anyone on the list tried using apt-cacher-ng with squid?
Below is my squid.conf and some output from apt taken from the Pi3 running squid.