nix-how / marsnix Goto Github PK

Currently, one problem that marsnix has is that it only provides inputs for one specific nixpkgs revision.
This means that one might run into trouble when building outputs which are based on any other nixpkgs revision.

It would be great if marsnix could provide all inputs for all nixpkgs revisions that have been released during a certain time period, like for example everything between nixos-22.05 and master.
For example, the user could specify a minimum nixpkgs revision, so that marsnix would evaluate and download all inputs of all nixpkgs revisions that have been created after that minimum revision.

At first glance that sounds expensive, but maybe really isn't that bad. Since hydra doesn't evaluate every single nixpkgs revision, marsnix doesn't need to as well. Hydra only evaluates nixpkgs several times a day. Marsnix just needs to get the list of revisions from hydra, and evaluate exactly those revisions.

Still this might result in around 1000 revisions to evaluate for the time frame of one year, but the good thing is that the result of evaluating a revision can be cached forever. Therefore the computation cost only has to be paid once, when the user activates the marsnix service for the first time.

Currently marsnix does not create garbage collection roots. That is bad because all downloaded files might be wiped by the next garbage collect.

Marsnix could be a lot quicker, if the list of derivations to substitute would not have to be computed on each client.
The marsnix project could set-up a github action that pre-computes the list of dervations required for a specific nixpkgs revision.

This is especially useful regarding #3

marsnix should have a nixos module, setting up a daemon, that regularly syncs the FODs with the latest nixpkgs releases.