Nix 2.26+, the local registries are ignored during lock writes by design, so there's an error for looking up nixpkgs-matrix and nixpkgs-matrix-private

[CMCDragonkai]

Describe the bug

• Attempting to run nix flake update commands
• Then we try to update the home manager lock file. This is done with nix flake update --flake ~/.config/home-manager
• However the new nix update, means that lockfile updates ignore system level registry, this causes an error.

  With 2.26+, local registries are ignored during lock writes by design, so your intent (host decides) is undermined at the exact moment you need it (locking).

• Quick fix is to use --override-input.

  nix flake update --flake ~/.config/home-manager --override-input nixpkgs-matrix-private github:MatrixAI/nixpkgs-matrix-private
  

• This is a problem for nixpkgs-matrix and nixpkgs-matrix-private TOO. After updating the flake.nix, the lock has to be updated, and that lock updating has to be propagated to nixpkgs-matrix-private, then finally to our own nixos machine too. Each one requires updating the lock file, and referencing the upstream updated git repository too.
• Long term fix is to host our own global flake registry - we can make it extend the https://channels.nixos.org/flake-registry.json. This just means we override the global registry, and so package aliases will depend on our own registry. This would replace the NixOS configuration that currently sets up nixpkgs-matrix and nixpkgs-matrix-private as system-level registries.

To Reproduce

Try using nix develop when you don't have the necessary lock file.

Expected behavior

Should just pull in the relevant system flake registry.

»» ~
 ♖ nix registry list                                                                                                                                                                        pts/2 19:52:20
system flake:nixpkgs path:/nix/store/4danq4f7rxpsax7bx18709c533v9krii-source
system flake:nixpkgs-matrix github:MatrixAI/nixpkgs-matrix
system flake:nixpkgs-matrix-private github:MatrixAI/nixpkgs-matrix-private
global flake:agda github:agda/agda
global flake:agenix github:ryantm/agenix
global flake:arion github:hercules-ci/arion
global flake:blender-bin github:edolstra/nix-warez?dir=blender
global flake:bundlers github:NixOS/bundlers
global flake:cachix github:cachix/cachix
global flake:composable github:ComposableFi/composable
global flake:disko github:nix-community/disko
global flake:dreampkgs github:nix-community/dreampkgs
global flake:dwarffs github:edolstra/dwarffs
global flake:emacs-overlay github:nix-community/emacs-overlay
global flake:fenix github:nix-community/fenix
global flake:flake-parts github:hercules-ci/flake-parts
global flake:flake-utils github:numtide/flake-utils
global flake:helix github:helix-editor/helix
global flake:hercules-ci-agent github:hercules-ci/hercules-ci-agent
global flake:hercules-ci-effects github:hercules-ci/hercules-ci-effects
global flake:home-manager github:nix-community/home-manager
global flake:hydra github:NixOS/hydra
global flake:mach-nix github:DavHau/mach-nix
global flake:ngipkgs github:ngi-nix/ngipkgs
global flake:nickel github:tweag/nickel
global flake:nix github:NixOS/nix
global flake:nix-darwin github:nix-darwin/nix-darwin
global flake:nix-serve github:edolstra/nix-serve
global flake:nixops github:NixOS/nixops
global flake:nixos-anywhere github:nix-community/nixos-anywhere
global flake:nixos-hardware github:NixOS/nixos-hardware
global flake:nixos-homepage github:NixOS/nixos-homepage
global flake:nixos-search github:NixOS/nixos-search
global flake:nixpkgs github:NixOS/nixpkgs/nixpkgs-unstable
global flake:nixvim github:nix-community/nixvim
global flake:nur github:nix-community/NUR
global flake:patchelf github:NixOS/patchelf
global flake:poetry2nix github:nix-community/poetry2nix
global flake:pridefetch github:SpyHoodle/pridefetch
global flake:sops-nix github:Mic92/sops-nix
global flake:systems github:nix-systems/default
global flake:templates github:NixOS/templates

Screenshots

Platform

»» ~
 ♖ nix --version                                                                                                                                                                            pts/2 19:52:22
nix (Nix) 2.28.4

Additional context

Notify maintainers

[linear]

INF-149

[CMCDragonkai]

It's annoying because basically our flake.nix relies on indirect inputs like:

  inputs = {
    nixpkgs-matrix-private = {
      type = "indirect";
      id = "nixpkgs-matrix-private";
    };
    flake-utils.url = "github:numtide/flake-utils";
  };

Which means it was supposed to rely system registry. But it's not. So hosting our own global registry is the solution in this case.