tjh.dev
1# udevCheckHook {#udevcheckhook}
2
3The `udevCheckHook` derivation adds `udevCheckPhase` to the [`preInstallCheckHooks`](#ssec-installCheck-phase),
4which finds all udev rules in all outputs and verifies them using `udevadm verify --resolve-names=never --no-style`.
5It should be used in any package that has udev rules outputs to ensure the rules are and stay valid.
6
7The hook runs in `installCheckPhase`, requiring `doInstallCheck` is enabled for the hook to take effect:
8```nix
9{
10 lib,
11 stdenv,
12 udevCheckHook,
13# ...
14}:
15
16stdenv.mkDerivation (finalAttrs: {
17 # ...
18
19 nativeInstallCheckInputs = [ udevCheckHook ];
20 doInstallCheck = true;
21
22 # ...
23})
24```
25Note that for [`buildPythonPackage`](#buildpythonpackage-function) and [`buildPythonApplication`](#buildpythonapplication-function), `doInstallCheck` is enabled by default.
26
27All outputs are scanned for their `/{etc,lib}/udev/rules.d` paths.
28If no rule output is found, the hook is basically a no-op.
29
30The `udevCheckHook` adds a dependency on `systemdMinimal`.
31It is internally guarded behind `hostPlatform` supporting udev and `buildPlatform` being able to execute `udevadm`.
32The hook does not need explicit platform checks in the places where it is used.
33
34The hook can be disabled using `dontUdevCheck`, which is necessary if you want to run some different task in `installCheckPhase` on a package with broken udev rule outputs.