NUR

The Nix User Repository (NUR) is community-driven meta repository for Nix packages. It provides access to user repositories that contain package descriptions (Nix expressions) and allows you to install packages by referencing them via attributes. In contrast to Nixpkgs, packages are built from source and are not reviewed by any Nixpkgs member.

The NUR was created to share new packages from the community in a faster and more decentralized way.

NUR automatically checks its list of repositories and performs evaluation checks before it propagates the updates.

Installation

First include NUR in your packageOverrides:

To make NUR accessible for your login user, add the following to ~/.config/nixpkgs/config.nix:

{
  packageOverrides = pkgs: {
    nur = import (builtins.fetchTarball "https://github.com/nix-community/NUR/archive/master.tar.gz") {
      inherit pkgs;
    };
  };
}

For NixOS add the following to your /etc/nixos/configuration.nix:

{
  nixpkgs.config.packageOverrides = pkgs: {
    nur = import (builtins.fetchTarball "https://github.com/nix-community/NUR/archive/master.tar.gz") {
      inherit pkgs;
    };
  };
}

Pinning

Using builtins.fetchTarball without a sha256 will only cache the download for 1 hour by default, so you need internet access almost every time you build something. You can pin the version if you don't want that:

builtins.fetchTarball {
  # Get the revision by choosing a version from https://github.com/nix-community/NUR/commits/master
  url = "https://github.com/nix-community/NUR/archive/3a6a6f4da737da41e27922ce2cfacf68a109ebce.tar.gz";
  # Get the hash by running `nix-prefetch-url --unpack <url>` on the above url
  sha256 = "04387gzgl8y555b3lkz9aiw9xsldfg4zmzp930m62qw8zbrvrshd";
}

How to use

Then packages can be used or installed from the NUR namespace.

$ nix-shell -p nur.repos.mic92.hello-nur
nix-shell> hello
Hello, NUR!

$ nix-env -iA nur.repos.mic92.hello-nur

# configuration.nix
environment.systemPackages = with pkgs; [
  nur.repos.mic92.hello-nur
];

Each contributor can register their repository under a name and is responsible for its content.

NUR does not check the repository for malicious content on a regular basis and it is recommended to check the expressions before installing them.

Using modules overlays or library functions in NixOS

If you intend to use modules, overlays or library functions in your NixOS configuration.nix, you need to take care to not introduce infinite recursion. Specifically, you need to import NUR like this in the modules:

{ pkgs, config, lib, ... }:
let
  nur-no-pkgs = import (builtins.fetchTarball "https://github.com/nix-community/NUR/archive/master.tar.gz") {};
in {

  imports = [
    nur-no-pkgs.repos.paul.modules.foo
  ];

  nixpkgs.overlays = [
    nur-no-pkgs.repos.ben.overlays.bar
  ];

}

Integrating with Home Manager

Integrating with Home Manager can be done by adding your modules to the imports attribute. You can then configure your services like usual.

let
  nur-no-pkgs = import (builtins.fetchTarball "https://github.com/nix-community/NUR/archive/master.tar.gz") {};
in
{
  imports = lib.attrValues nur-no-pkgs.repos.moredhel.hmModules.modules;

  services.unison = {
    enable = true;
    profiles = {
      org = {
        src = "/home/moredhel/org";
        dest = "/home/moredhel/org.backup";
        extraArgs = "-batch -watch -ui text -repeat 60 -fat";
      };
    };
  };
}

Finding packages

At the moment we do not have a dedicated package search available. However our nur-combined repository contains all nix expressions from all users and can be search via github.

How to add your own repository.

First create a repository that contains a default.nix in its top-level directory. We also provide repository template that contains a prepared directory structure.

DO NOT import packages for example with import <nixpkgs> {};. Instead take all dependency you want to import from Nixpkgs from the given pkgs argument. Each repository should return a set of Nix derivations:

{ pkgs }:
{
  hello-nur = pkgs.callPackage ./hello-nur {};
}

In this example hello-nur would be a directory containing a default.nix:

{ stdenv, fetchurl }:

stdenv.mkDerivation rec {
  pname = "hello";
  version = "2.10";

  src = fetchurl {
    url = "mirror://gnu/hello/${pname}-${version}.tar.gz";
    sha256 = "0ssi1wpaf7plaswqqjwigppsg5fyh99vdlb9kzl7c9lng89ndq1i";
  };

  postPatch = ''
    sed -i -e 's/Hello, world!/Hello, NUR!/' src/hello.c
  '';

  # fails due to patch
  doCheck = false;

  meta = with stdenv.lib; {
    description = "A program that produces a familiar, friendly greeting";
    longDescription = ''
      GNU Hello is a program that prints "Hello, world!" when you run it.
      It is fully customizable.
    '';
    homepage = https://www.gnu.org/software/hello/manual/;
    changelog = "https://git.savannah.gnu.org/cgit/hello.git/plain/NEWS?h=v${version}";
    license = licenses.gpl3Plus;
    maintainers = [ maintainers.eelco ];
    platforms = platforms.all;
  };
}

You can use nix-shell or nix-build to build your packages:

$ nix-shell --arg pkgs 'import <nixpkgs> {}' -A hello-nur
nix-shell> hello
nix-shell> find $buildInputs

$ nix-build --arg pkgs 'import <nixpkgs> {}' -A hello-nur

For development convenience, you can also set a default value for the pkgs argument:

{ pkgs ? import <nixpkgs> {} }:
{
  hello-nur = pkgs.callPackage ./hello-nur {};
}

$ nix-build -A hello-nur

Add your own repository to in the repos.json of NUR:

$ git clone https://github.com/nix-community/NUR
# open and modify repos.json in an editor

{
    "repos": {
        "mic92": {
            "url": "https://github.com/Mic92/nur-packages"
        },
        "<fill-your-repo-name>": {
            "url": "https://github.com/<your-user>/<your-repo>"
        }
    }
}

At the moment each URL must point to a git repository. By running bin/nur update the corresponding repos.json.lock is updated and the repository is tested. This will perform also an evaluation check, which must be passed for your repository. Commit the changed repos.json but NOT repos.json.lock

$ git add repos.json
$ ./bin/nur format-manifest # ensure repos.json is sorted alphabetically
$ git commit -m "add <your-repo-name> repository"
$ git push

and open a pull request towards https://github.com/nix-community/NUR.

At the moment repositories should be buildable on Nixpkgs unstable. Later we will add options to also provide branches for other Nixpkgs channels.

Use a different nix file as root expression

To use a different file instead of default.nix to load packages from, set the file option to a path relative to the repository root:

{
    "repos": {
        "mic92": {
            "url": "https://github.com/Mic92/nur-packages",
            "file": "subdirectory/default.nix"
        }
    }
}

Update NUR's lock file after updating your repository

By default we only check for repository updates once a day with an automatic cron job in travis ci to update our lock file repos.json.lock. To update NUR faster, you can use our service at https://nur-update.herokuapp.com/ after you have pushed an update to your repository, e.g.:

curl -XPOST https://nur-update.herokuapp.com/update?repo=mic92

Check out the github page for further details

Git submodules

To fetch git submodules in repositories set submodules:

{
    "repos": {
        "mic92": {
            "url": "https://github.com/Mic92/nur-packages",
            "submodules": true
        }
    }
}

NixOS modules, overlays and library function support

It is also possible to define more than just packages. In fact any Nix expression can be used.

To make NixOS modules, overlays and library functions more discoverable, we propose to put them in their own namespace within the repository. This allows us to make them later searchable, when the indexer is ready.

Providing NixOS modules

NixOS modules should be placed in the modules attribute:

{ pkgs }: {
  modules = import ./modules;
}

# modules/default.nix
{
  example-module = ./example-module.nix;
}

An example can be found here. Modules should be defined as paths, not functions, to avoid conflicts if imported from multiple locations.

Providing Overlays

For overlays use the overlays attribute:

# default.nix
{
  overlays = {
    hello-overlay = import ./hello-overlay;
  };
}

# hello-overlay/default.nix
self: super: {
  hello = super.hello.overrideAttrs (old: {
    separateDebugInfo = true;
  });
}

Providing library functions

Put reusable nix functions that are intend for public use in the lib attribute:

{ pkgs }:
with pkgs.lib;
{
  lib = {
    hexint = x: hexvals.${toLower x};

    hexvals = listToAttrs (imap (i: c: { name = c; value = i - 1; })
      (stringToCharacters "0123456789abcdef"));
  };
}

Overriding repositories

You can override repositories using repoOverrides argument. This allows to test changes before publishing.

{
  packageOverrides = pkgs: {
    nur = import (builtins.fetchTarball "https://github.com/nix-community/NUR/archive/master.tar.gz") {
      inherit pkgs;
      repoOverrides = {
        mic92 = import ../nur-packages;
        ## remote locations are also possible:
        # mic92 = import (builtins.fetchTarball "https://github.com/your-user/nur-packages/archive/master.tar.gz");
      };
    };
  };
}

Contribution guideline

When adding packages to your repository make sure they build and set meta.broken attribute to true otherwise.
Supply meta attributes as described in the Nixpkgs manual, so packages can be found by users.
Keep your repositories slim - they are downloaded by users and our evaluator and needs to be hashed.
Reuse packages from Nixpkgs when applicable, so the binary cache can be leveraged

Examples for packages that could be in NUR:

Packages that are only interesting for a small audience
Pre-releases
Old versions of packages that are no longer in Nixpkgs, but needed for legacy reason (i.e. old versions of GCC/LLVM)
Automatic generated package sets (i.e. generate packages sets from PyPi or CPAN)
Software with opinionated patches
Experiments

Why package sets instead of overlays?

To make it easier to review nix expression NUR makes it obvious where the package is coming from. If NUR would be an overlay malicious repositories could override existing packages. Also without coordination multiple overlays could easily introduce dependency cycles.

Contact

You can chat with us on IRC in channel #nixos-nur. Apart from that we also read posts on https://discourse.nixos.org.

Roadmap

Implement a search to find packages

trevorriles/NUR

NUR