nixos-config/nix/sources.json

{
    "home-manager": {
        "branch": "release-21.11",
        "description": "Manage a user environment using Nix  [maintainer=@rycee] ",
        "homepage": "https://nix-community.github.io/home-manager/",
        "owner": "nix-community",
        "repo": "home-manager",
        "rev": "a8d00f5c038cf7ec54e7dac9c57b171c1217f008",
        "sha256": "1ix6cknhlrwpawlakrsd3616rgy1calnds2h6wfqrv6cfdwsyzzc",
        "type": "tarball",
        "url": "https://github.com/nix-community/home-manager/archive/a8d00f5c038cf7ec54e7dac9c57b171c1217f008.tar.gz",
        "url_template": "https://github.com/<owner>/<repo>/archive/<rev>.tar.gz"
    },
    "niv": {
        "branch": "master",
        "description": "Easy dependency management for Nix projects",
        "homepage": "https://github.com/nmattia/niv",
        "owner": "nmattia",
        "repo": "niv",
        "rev": "9cb7ef336bb71fd1ca84fc7f2dff15ef4b033f2a",
        "sha256": "1ajyqr8zka1zlb25jx1v4xys3zqmdy3prbm1vxlid6ah27a8qnzh",
        "type": "tarball",
        "url": "https://github.com/nmattia/niv/archive/9cb7ef336bb71fd1ca84fc7f2dff15ef4b033f2a.tar.gz",
        "url_template": "https://github.com/<owner>/<repo>/archive/<rev>.tar.gz"
    }
}