Hooks

Overview

flake-file provides two hook lists:

• flake-file.write-hooks — commands executed after write-flake writes flake.nix.
• flake-file.check-hooks — commands executed during nix flake check.

Each hook is an attrset with an index (for ordering) and a command.

write-hooks

Use write-hooks to trigger follow-up actions whenever flake.nix is regenerated — for example, updating a lock file or reformatting.

{ pkgs, ... }: {
  flake-file.write-hooks = [
    {
      index = 10;
      exec = "${pkgs.nix}/bin/nix flake update";
    }
  ];
}

Hooks run in ascending index order, so you can coordinate between modules without knowing the full list.

check-hooks

Use check-hooks to add extra validation during nix flake check — for example, checking that a derived file is up to date.

{ pkgs, ... }: {
  flake-file.check-hooks = [
    {
      index = 10;
      exec = "${pkgs.my-linter}/bin/my-linter --check .";
    }
  ];
}

Practical uses

• Run nix flake update automatically after regeneration.
• Reformat flake.nix with a formatter (see flake-file.formatter).
• Validate generated files in CI via check-hooks.
• Trigger allfollow or nix-auto-follow to flatten the lock file.