Workflows & Automation

GitHub Workflow Token

If you edit the CI workflows, your token needs the workflow scope:

gh auth status       # Check current scopes
gh auth login --scopes workflow

Formatting

nix fmt runs whatever package the flake’s formatter output points at (flake.nix’s formatter.${system}), currently nixfmt-tree. Three different tools are involved and it’s easy to mix them up:

• nixfmt — the official NixOS Foundation formatter. It formats a single file (or stdin), which makes it the right thing to point your editor’s format-on-save at.
• treefmt — a multi-language formatter orchestrator by numtide. It walks the whole repo tree and dispatches each file to the formatter configured for its type.
• nixfmt-tree — a small nixpkgs package that is not the upstream version of Numtide’s treefmt-nix (that’s a separate flake module numtide also publishes for configuring treefmt from Nix; unused here). It’s just treefmt pre-wired to run nixfmt on every *.nix file, i.e. “zero-setup nix fmt for a Nix repo”.

So nix fmt == treefmt-wide formatting using nixfmt under the hood, while nixfmt on its own is the single-file tool for IDE integration.

The pre-commit hook (.pre-commit-config.yaml, run via prek) invokes nix fmt -- --fail-on-change --no-cache: it reformats any unformatted files in place and fails the commit if anything changed, so re-stage and commit again. treefmt has no dry-run/check flag that skips writing.

Facter

Generate a hardware report for a new system:

sudo nix run \
  --option experimental-features "nix-command flakes" \
  --option extra-substituters https://numtide.cachix.org \
  --option extra-trusted-public-keys numtide.cachix.org-1:2ps1kLBUWjxIneOy1Ik6cQjb41X0iXVXeHigGmycPPE= \
  github:numtide/nixos-facter -- -o facter.json

Place the output in systems/<arch>/<host>/facter.json.