Ubuntu 20.04 images result in 403 error

Hi there,

I hope this is the right place to start this bug report. With Ubuntu 20.04 Canonical introduced their new Auto Install feature which shall replace Debian preseed and therefore changed the paths to the netinstall kernel and initrd which (I believe) breaks apt-cacher-ng behaviour and results in 403 errors.

So with Ubuntu 18.04 the path was:

http://archive.ubuntu.com/ubuntu/dists/bionic/main/installer-amd64/current/images/netboot/ubuntu-installer/amd64/linux

With Ubuntu 20.04 it is:

http://archive.ubuntu.com/ubuntu/dists/focal/main/installer-amd64/current/legacy-images/netboot/ubuntu-installer/amd64/linux

See images -> legacy-images

I am absolutely not familiar with C++ but I think there need to be changes in the regular expression in the following lines:

• https://salsa.debian.org/blade/apt-cacher-ng/-/blob/next/source/acfg_defaults.cc#L45
• https://salsa.debian.org/blade/apt-cacher-ng/-/blob/next/source/acfg_defaults.cc#L88

Please let me know if I can provide a MR if necessary or please point me in the right direction for a fix.

Thanks in advance

Sebastian