evaluator: fails to use available nix-eval-jobs

[plumj-am]

Error:

May 27 20:57:18 plum circus-evaluator[1160581]: 2026-05-27T18:57:18.929242Z  
INFO evaluate:evaluate_flake: circus_evaluator::nix: nix-eval-jobs unavailable, 
falling back to nix eval repo_path="/tmp/circus-evaluator/nixos" timeout=3600s 
repo_path="/tmp/circus-evaluator/nixos" nix_expression="checks" timeout=3600s

systemctl show circus-evaluator -p Environment | grep -o 'PATH=[^"]*':

PATH=/nix/store/dfsqsd1y94fxy1a99qg52hjfswpgzi09-nix-2.34.7/bin:
/nix/store/c0277k5giric1mn9dklllavbzvxl6hzb-git-2.53.0/bin:
/nix/store/ar68kaxff430f9zx2jpd3p460vivw5xw-nix-eval-jobs-2.34.1/bin: # <-- It's here!
/nix/store/jjxngswsb214vb58qx485jhmilf0kxxy-coreutils-9.10/bin:
/nix/store/vhsirn9m1ifmnw5g1qczzhvqkx6lw1if-findutils-4.10.0/bin:
/nix/store/wf7lr2hf43546jc5kwqh3dbxnpcnw1mn-gnugrep-3.12/bin:
/nix/store/af4a8i43kc2ss4rnmf0swkk2mprsw6xq-gnused-4.9/bin:
/nix/store/9rpism89x6lyjcwzzkp6kana25rs03nn-systemd-260.1/bin:
/nix/store/dfsqsd1y94fxy1a99qg52hjfswpgzi09-nix-2.34.7/sbin:
/nix/store/c0277k5giric1mn9dklllavbzvxl6hzb-git-2.53.0/sbin:
/nix/store/ar68kaxff430f9zx2jpd3p460vivw5xw-nix-eval-jobs-2.34.1/sbin:
/nix/store/jjxngswsb214vb58qx485jhmilf0kxxy-coreutils-9.10/sbin:
/nix/store/vhsirn9m1ifmnw5g1qczzhvqkx6lw1if-findutils-4.10.0/sbin:
/nix/store/wf7lr2hf43546jc5kwqh3dbxnpcnw1mn-gnugrep-3.12/sbin:
/nix/store/af4a8i43kc2ss4rnmf0swkk2mprsw6xq-gnused-4.9/sbin:
/nix/store/9rpism89x6lyjcwzzkp6kana25rs03nn-systemd-260.1/sbin TZDIR=/nix/store/cxjmhdbpy3bk12jc6lwpmcvlas76a7zm-tzdata-2026a/share/zoneinfo

My only idea thus far is that nix-eval-jobs needs something like trusted-users/allowed-users to include the "circus" user but that's probably wrong because then normal nix eval wouldn't work, I think.

[plumj-am]

So no, it isn't caused by allowed-users because by default it is [ "*" ] and I have tested it on my fork/system. I can try trusted-users but I don't think that's the best idea.

[plumj-am]

It IS caused by the allowed-users settings. I mixed up the times and misread my logs... There appears to be 2 options: allowed-users and extra-allowed-users.

allowed-users is [ "*" ] by default and extra-allowed-users is completely undocumented but attempting to evaluate it in my configs tells me the attribute doesn't exist.

buildbot-nix makes use of it here and also uses nix-eval-jobs without any issues: https://github.com/nix-community/buildbot-nix/blob/8644b7988debf93de7d46024e9173e0d9e155ce4/nixosModules/worker.nix#L86

Setting extra-allowed-users = [ "circus" ]; solves the problem without clobbering the allowed-users.

I'll open a PR anyway with a summary there, just documenting it for anyone in the future.

[plumj-am]

Sadly this still appears to be an issue:

May 28 20:33:23 plum circus-evaluator[454038]: 2026-05-28T18:33:23.681669Z  
INFO evaluate:evaluate_flake: circus_evaluator::nix: nix-eval-jobs unavailable, falling 
back to nix eval repo_path="/tmp/circus-evaluator/nixos" timeout=3600s repo_path="/tmp
/circus-evaluator/nixos" nix_expression="checks" timeout=3600s

@NotAShelf please can you re-open? I don't have permission.

[NotAShelf]

We could wrap nix-eval-jobs in the evaluator package.