README

This repository provides pure nix code to manage bundles of packages using nix in a modular way. You can use a pure default.nix, shell.nix file to use it or if you prefer flakes you can use a flake.nix.

Specifying Layered Package Sets

If you want to bundle all your projects in one place and build them consistently as a set with a single build command or make them all available in a nix shell -- you can conveniently specify such an environment using nixpack. You can specify different layers overriding each other -- e.g. if you want packages from hackage only, or if you want hackge + overrides from your github repos, or you want hackage + github + your local repositories -- all these use cases are conveniently supported with easy selection of layers you want.

See the flake.bundle.nix or default.bundle.nix files for an example usage.

Copy and edit the above file and add the sources of your packages (github repositories or hackage locations) in sources.nix and the list of packages that you want to select as the nix environment or nix shell in the packages.nix file.

Building an Individual Package

Example:

nix build "git+ssh://[email protected]/composewell/nixpack.git#streamly"

Override the Master set in a project

Assuming you are maintianing a master package set as described above you may now want to use that set or a subset of it and maybe with some overrides as dependencies in individual projects. That use case is also conveniently supported. You can merge sources of the master set and sources of your project repo to create a overridden source set and use that to create a nix shell.

Example flake.nix for dev projects

Copy the flake.dev.nix file in the project repo, update the nixpack repo revision in it and add a sources.nix and packages.nix file.

A sample packages.nix:

{ nixpkgs }:
{
dev-packages = with nixpkgs.haskellPackages; [ streamly ];
}

A sample sources.nix. Be careful to spell attribute name you are overriding from nixpack correctly, if the name is different the override wll not occur and you will be using the version from nixpack unknowingly. Also note that tests are automatically disabled for custom derivations defined using the functions from nixpack.sources:

{nixpack}:
with nixpack.sources;
{
layers = [ { streamly = local ./.; } ];
}

Finding Outdated Revisions in sources.nix

If any of the sources have been updated upstream you can find if the sources in your bundle or project are stale and eed to be updated.

Use the (nixpack/nix).listSources function to create a manifest of sources and use nixpack/bin/nixpack-outdated.sh on the result to find the stale sources.

For example, you can do that by running these commands from the repo root:

nix-build -E '
  let
    nixpackSrc = builtins.fetchTarball "https://github.com/composewell/nixpack/archive/d8c97426bd697.tar.gz";
    nixpack = import (nixpackSrc + "/nix");
  in nixpack.listSources { sources = ./sources.nix; }
'
bin/nixpack-outdated.sh ./result