Rippkgs

rippkgs is a search CLI utility for searching indexed nixpkgs expressions.

Usage

Installation

Once NixOS/nixpkgs#305125 is merged, if you have the commit you can use install using your preferred way of installing nixpkgs derivations. For example:

$ nix profile install nixpkgs#rippkgs nixpkgs#rippkgs-index
# alternatively, via the flake directly
$ nix profile install github:replit/rippkgs/v1.1.0

Alternatively, if you're using a flake to configure your system, you can add rippkgs via nixpkgs or as an input to your flake and add rippkgs to your environment packages. For example, in NixOS:

environment.systemPackages = [
  pkgs.rippkgs
  pkgs.rippkgs-index
  # alternatively, if via the flake input:
  inputs.rippkgs.packages.${system}.rippkgs
  inputs.rippkgs.packages.${system}.rippkgs-index
];

Generate an index

Generating an index may be done with the rippkgs-index cli:

rippkgs-index nixpkgs -o $XDG_DATA_HOME/rippkgs-index.sqlite

If you don't have a nixpkgs channel set (or would prefer to index a different channel), you'll have to explicitly pass the dir to the nixpkgs distribution:

rippkgs-index nixpkgs -o $XDG_DATA_HOME/rippkgs-index.sqlite ~/.nix-defexpr/channels/my-very-special-nixpkgs-channel

Alternatively, you can generate a registry using the flake output lib.genRegistry, which allows you to avoid recursive-nix problems:

$ nix eval -L .#lib.genRegistry --apply 'f: f (import <nixpkgs> { })' --impure --json >registry.json
$ rippkgs-index registry -o rippkgs-index.sqlite registry.json

Searching

Use the rippkgs cli to search for appropriate packages:

rippkgs rustc

Comparison

nix-env -q is historically the command that's used to achieve what rippkgs achieves, but the nix evaluation cost is high. When in an environment where reactiveness is desirable, it's better to pay the initial cost of generating the index (see results below).

nix-index is similar in that it operates on a generated database, but requires derivations to be built in order to generate the index, and not all package information is stored in the index. This means you have to augment nix-locate results with nix-env in order to get additional information about a package, like its version or the nixpkgs registry description for the package.

https://search.nixos.org is the closest approximate tool to rippkgs, but unfortunately it comes with a few shortcomings:

1. The index only tracks up-to-date nixpkgs distributions, which means you must resort to nix-env to get results accurate to the nixpkgs release you're using.
2. Search is only available as a web service with only HTML responses to its HTTP api, which means you have to parse the HTML response to your programmatic requests.
3. It uses Elastic Search, which is fine for a widely-used service but doesn't work well when providing highly-localized results.

Performance

Using nixpkgs@b550fe4b4776908ac2a861124307045f8e717c8e on an aarch64-darwin with 16gb of memory:

$ time ./target/release/rippkgs-index nixpkgs -o nixpkgs.sqlite
evaluated registry in 289.8638 seconds
parsed registry in 0.0761 seconds
wrote index in 0.1432 seconds
./target/release/rippkgs-index nixpkgs -o nixpkgs.sqlite  108.35s user 45.50s system 53% cpu 4:50.20 total

$ time ./target/release/rippkgs -i nixpkgs.sqlite rustc 1>/dev/null
got results in 44 ms
./target/release/rippkgs -i nixpkgs.sqlite rustc > /dev/null  0.03s user 0.02s system 89% cpu 0.051 total