Nice! Great job in moving this to building from source. Looking at the change, how is the yarn lock v1 generated? Are you considering automating this process through an update script so that we get "free" updates for that too?

There is a comment decribing how to generate the yarn.lock. I don't think it's worth automating as it is literaly a single operation.

I don't think it's a blocker for this PR, but the reasoning to avoid automating it is IMHO poor. Also updating a binary package is only "one operation" (clone nixpkgs, zero out the hash, update the version, run the build, copy-paste the updated hash), but when there are 80k packages to regularly update, having it automated makes sense, especially as there's a bot that does it. Nexus shouldn't be an exception.

To update the yarn.lock, it looks like to me that:

1. git, node and yarn must be at a minimum present
2. the correct version of the nexus source to be cloned in a folder
3. cd in that folder
4. run yarn / yarn install there
5. copy the resulting yarn.lock in the right dir in nixpkgs

If you have a look at other update scripts, you see they take similar steps in doing custom update processes.

Also related to the yarn.lock: how do we ensure the generated one is equivalent / compatible with the official v2? Is there some form of automated test that can be run?

Can you point me at an example update script so that I can crib?

@zaninime ?

https://github.com/NixOS/nixpkgs/blob/master/pkgs/tools/misc/sharedown/update.sh as an example.

This pull request has been mentioned on NixOS Discourse. There might be relevant details there:

https://discourse.nixos.org/t/prs-ready-for-review/3032/3648