https://github.com/cachix/pre-commit-hooks.nix
https://blog.hercules-ci.com/nix/2019/08/22/pre-commit-git-hooks-for-nix/

private repos
https://www.mpscholten.de/nixos/2016/07/07/private-github-repositories-and-nixos.html

https://huijzer.xyz/posts/nixos/
    Storing Git credentials took me way too long to figure out. So, here it is. To use the Git credential helper libsecret (gnome-keyring) write

    # /etc/nixos/home-manager/git.nix

    environment.systemPackages = [
      pkgs.gitAndTools.gitFull # gitFull contains libsecret.
    ]

    home-manager.users.rik.programs.git = {
      enable = true;

      # Some omitted settings.

      extraConfig = {
        credential.helper = "libsecret";
      };
    };