`fetchzip` calls aren't picked up by tarballs.nixos.org

[Olliroxx]

Issue description

This is the file that gets the list of tarballs to mirror on tarballs.nixos.org. On line 21, it filters out all packages which do not have the hash mode flat. In fetchzip it sets the recursiveHash option, which sets the hash mode to recursive, meaning anything that uses fetchzip (or others that use it, like fetchFromGitHub) isn't mirrored.

Potential solutions:

Ignore it Cons:

• Every package which fetches its source from github, gitlab or similar isn't covered by tarballs.nixos.org (but even if this was fixed, there won't be 100% coverage due to some packages using fetchFromGitHub in a way that uses fetchGit instead of fetchzip)

Pros:

• Minimal effort

Modify fetchzip to instead copy the result of a fetchurl call and unpack it (resulting in two derivations instead of one) Cons:

• Requires rebuilding anything which uses fetchzip, and dependents (though I know fetchurl outputs are content addressed by default, could that be extended to the output of fetchzip?)
• More disk usage, though it'll almost definitely be garbage collected anyway

Pros:

• Feels like the least hacky solution

Modify find-tarballs.nix to also cache directories Cons:

• Also needs a modification to nix
• I feel like there was a reason this wasn't done in the first place?
• Sources will be uncompressed

Pros:

• Doesn't require a mass-rebuild of nixpkgs

[veprbl]

fetchFromGithub could grab sources from Software Heritage instead.