Utilizing Apt-Cacher-NG’s cache on the server hosting it

I’ve been using apt-cacher-ng for a few months now. For those who don’t know, this is a service you can run locally which will proxy apt requests from your network clients. This way, each time a package or update is requested there will be a copy retained in the cache. Upon each subsequent request for the same file(s), the local copy can be served instead. This saves bandwidth, and offers a speed advantage since you’ll likely be getting full GB ethernet line speed on your LAN. Read more about ACNG here.

While several local machines and VMs have no issues using my local ACNG proxy, the server actually hosting ACNG itself seemed to be giving errors when doing an apt update.

You’ll likely see the warnings “503 Server reports unexpected range” as well as “Some index files failed to download. They have been ignored, or old ones used instead.”

Basically, because the machine is trying to proxy through itself, some kind of problem occurs. Now, the simple solution is to just point to the normal Debian mirrors directly. That however wouldn’t offer the benefit of our local cache! The more boxes / VMs pulling for it, the more value you’re getting out of the whole setup… So here’s how we resolve this issue.

Write a text file to /etc/apt/apt.conf.d/00acng and place the following lines inside:

Acquire::http::Proxy::localhost “DIRECT”;
Acquire::http::Proxy::127.0.0.1 “DIRECT”;
Acquire::http::Proxy::novo.lan “DIRECT”;

Of course, change “novo.lan” to the hostname of your ACNG host. My sources.list looks like this, hence the hostname used in my example.

deb http://novo.lan:3142/deb.debian.org/debian/ bookworm main non-free-firmware
deb-src http://novo.lan:3142/deb.debian.org/debian/ bookworm main non-free-firmware

deb http://novo.lan:3142/security.debian.org/debian-security bookworm-security main non-free-firmware
deb-src http://novo.lan:3142/security.debian.org/debian-security bookworm-security main non-free-firmware

deb http://novo.lan:3142/deb.debian.org/debian/ bookworm-updates main non-free-firmware
deb-src http://novo.lan:3142/deb.debian.org/debian/ bookworm-updates main non-free-firmware

You may want to add a 4th line, with your actual LAN IP if you’re naming the apt mirror by IP instead.