flake-input-patcher

Tired of waiting for PRs to land? Stop waiting!

Utility to patch nix flake inputs.

This can go away when nix supports patching flake inputs: NixOS/nix#3920.

Usage

Usage in a flake.nix:

{
  inputs = {
    flake-input-patcher.url = "github:jfly/flake-input-patcher";

    # Feel free to use `follows`. If it points at a patched input, the right
    # thing will happen!
    systems.follows = "dep1/systems";

    # ... More inputs here ...
  };

  outputs =
    unpatchedInputs:
    let
      # Unfortunately, this utility requires hardcoding a single system. See
      # "Known issues" below.
      patcher = unpatchedInputs.flake-input-patcher.lib.x86_64-linux;

      inputs = patcher.patch {
        inherit unpatchedInputs;
        flakePath = ./.;
        patchSpec = {
          # Patching a direct dependency:
          nixpkgs.patches = [
            (patcher.fetchpatch {
              name = "k3s: use patched util-linuxMinimal";
              url = "https://github.com/NixOS/nixpkgs/pull/407810.diff";
              hash = "sha256-N8tzwSZB9d4Htvimy00+Jcw8TKRCeV8PJWp80x+VtSk=";
            })
          ];

          # Patching a transitive dependency:
          clan-core.inputs.data-mesher.patches = [
             # ... More patches here ...
          ];
        };
      };
    in
    # Define your flake as normal using `inputs`!
}

Known issues

• nix does not (yet) have a patch builtin, so we use system-specific utilities in nixpkgs (fetchpatch and applyPatches), which means you have to hardcode a system to make it work.
• This depends on Input From Derivation (IFD).
• Support for input following depends on parsing your flake's flake.lock file. I'm not sure how brittle this approach is. See branch follows-without-lockfile-abandoned for an alternate approach that does not depend on the lockfile. I abandoned this approach before I got it completely working, but I think it is a viable approach, it just is much more work than leveraging the lockfile (which implicitly captures information about how inputs directives are resolved across multiple flakes).

Alternatives

• Be more patient and wait for PRs to land. You are trying to upstream your patches, aren't you?
• Tediously hand-write overlays/overrides for changes you need/want. This won't help with NixOS module changes.
• Maintain your own forks of your inputs.
  • nix-patcher is designed to automate this process. It looks like it only works for inputs hosted on GitHub.
• gepbird/nixpkgs-patcher implements a similar IFD helper. Also see this feature comparison table

In the wild

Feel free to add a link to your repo here!

• jfly/snow
• opdavies/nix-sculpin-template
• opdavies/oliverdavies.uk