FR: Problems using deb_index to install CUDA packages

[benmccown]

We've been trying to use deb_index to install the necessary CUDA packages that we ultimately need pulled into a rules_oci container image, where we're using Ubuntu 20.04 as our base.

We ran into a few different problems getting this to work since Nvidia's debian package repo doesn't adhere to the same principles as Ubuntu's package repo. For example, Ubuntu's Packages manifest for the apt repo is located at a very specific URL which is hardcoded here in rules_distroless. In Nvidia's case, the Packages manifest sits at the same URL as the packages themselves. So deb_index was incapable of finding the Packages manifest. We also ran into an issue where rules_distroless didn't support the Packages file being gzipped.

We also saw in _deb_package_index_impl that duplicate transitive dependencies weren't handled correctly which caused issues.

At this point these issues we ran into were about two months ago. I forked the project, fixed our issues, and have just now gotten back around to looking at my fork. I can patch rules_distroless using diff based patching in our team's project and move on, but I thought I'd open an issue and PR in case someone else wants to install CUDA packages and has similar problems.