let
  nixpkgs = {
    url = "https://github.com/NixOS/nixpkgs/";
    ref = "nixos-20.09";
    rev = ''
      <% git ls-remote https://github.com/nixos/nixpkgs nixos-20.09 | awk '{ print $1 }' | tr -d '
      ' -%>'';
  };
in
{
  inherit nixpkgs;
  nixos = nixpkgs // {
    suffix = "/nixos";
  };
  "channels-nixos-stable" = nixpkgs;
  "channels-nixos-unstable" = {
    url = "https://github.com/NixOS/nixpkgs/";
    ref = "nixos-unstable";
    rev = ''
      <% git ls-remote https://github.com/nixos/nixpkgs nixos-unstable | awk '{ print $1 }' | tr -d '
      ' -%>'';
  };
  "nixpkgs-master" = {
    url = "https://github.com/NixOS/nixpkgs/";
    ref = "master";
    rev = ''
      <% git ls-remote https://github.com/NixOS/nixpkgs.git master | head -n1 | awk '{ print $1 }' | tr -d '
      ' -%>'';
  };
  "home-manager-module" = {
    url = "https://github.com/nix-community/home-manager";
    ref = "release-20.09";
    rev = ''
      <% git ls-remote https://github.com/nix-community/home-manager.git release-20.09 | awk '{ print $1 }' | tr -d '
      ' -%>'';
  };
}