[solved] nix shell and nix profile not using the branch defined in flake.nix?

mobsenpai, 21 days ago

Its solved, see the mentioned link.

hallettj, 22 days ago (edited 15 days ago)

It’s possible (and I think advisable) to set your flake nixos config to set the system flake registry to point to the same nixpkgs revision that your flake uses. The nixos-starter-configs standard template has two lines that do this:

<span style="color:#323232;"># Opinionated: make flake registry and nix path match flake inputs
</span><span style="color:#323232;">registry = lib.mapAttrs (_: flake: {inherit flake;}) flakeInputs;
</span><span style="color:#323232;">nixPath = lib.mapAttrsToList (n: _: "${n}=flake:${n}") flakeInputs;
</span>

That actually adds all of your flake inputs to the system flake registry. So for example if in addition to your nixpkgs input you also have an input you named nixpkgs-unstable then can also reference that with stuff like nix shell. For example:

<span style="color:#323232;">nix shell nixpkgs#hello nixpkgs-unstable#cowsay
</span>

mobsenpai, 21 days ago

Yeah that’s what I am using currently but I was told that by default it follows whatever nixpkgs version is in flake.nix and doing the registry thing is an extra step to make it more systematic. For now I will keep using that.

rutrum, 22 days ago (edited 15 days ago)

You want to look at the registry. Run nix registry list. You’ll see that nixpkgs by default points to unstable. You override this in your config. I’ve done that, where nixpkgs is stable and “unstable” is unstable.

EDIT: heres part of my home manager config that changes this: github.com/rutrum/dots/blob/master/…/nix.nix#L15

mobsenpai, 21 days ago

Yeah mine also shows global flake:nixpkgs github:NixOS/nixpkgs/nixpkgs-unstable instead of what I have defined in flake.nix i.e 23.11