Some of the macs don't recognize my ssh keys, apparently, though most of them do. (I was running ./macs/mac-update as suggested.)

• hetzner@sweeping-filly.mac.nixos.org
• hetzner@maximum-snail.mac.nixos.org
• customer@eager-heisenberg.mac.nixos.org

BTW

root@mac05.ofborg.org | error: config contains the wrong home directory for hydra-queue-builder, aborting activation

Hey, I was looking into optimizations for build scheduling to account for substitution cost and was wondering how large (in terms of number/total size of derivations) the nix store was on builder nodes. This is mainly intended to make some guestimates about how expensive the query of "Which subset of a package's build graph is present on a builder node and how large (in total file size) is that subset?" is. My personal builders have varied from 250K-1M but they are almost certainly smaller/less used than the public builders.

I have looked through the data in the public Grafana instance but could not find an applicable metric. Could you please, if it is available somewhere, include this metrics in the Prometheus Instance for the NixOS Infra?

Alternatively, could someone with access to the nodes please look it up on a few builder nodes for me? It should be queriable via the sqlite DB (nix shell nixpkgs#sqlite -c sqlite3 /nix/var/nix/db/db.sqlite 'select count(*), sum(narSize) from ValidPaths' or (more expensive, without file size) by counting the store paths directly with ls -l /nix/store | wc -l)

I know, I plan to do some research on this for my baechelor thesis. iirc you or hexa (signing key rotation when) broght it up when I asked for relevant issues before in the offtopic channel. The main thing for me here was to not just count store paths though but instead the total size of the store paths (as , e.g., firefox-bin is heavier than harfbuzz).

My main plan here was to make a prototype with an extra agent/nix-scheduler-hook and use the results from testing there to propose changes to hydra queue runner later.