Reuse /run/current-system/sw instead of /run/system-manager

[bryango]

Is your feature request related to a problem? Please describe.

I was trying to adapt nixos modules for system-manager and noticed that many of them have hard-coded /run/current-system/sw; see e.g.

• https://github.com/search?q=repo%3ANixOS%2Fnixpkgs+%2Frun%2Fcurrent-system%2Fsw+NOT+path%3A%2F%5Enixos%5C%2Ftests%5C%2F%2F&type=code

One must modify /run/current-system -> /run/system-manager in order to port such modules.

Describe the solution you'd like

Since /run/current-system is not used in a generic non-NixOS system I believe we can simply re-use the path.

Describe alternatives you've considered

• As mentioned before, rename each /run/current-system -> /run/system-manager module by module.
• Alternatively, provide an option to symlink /run/current-system -> /run/system-manager when profiles are activated.

Additional context

I am not sure if it's safe to do this. It feels safe to me since system-manager should only be used on non-NixOS so there will not be conflicts. But I don't know.

[r-vdp]

I'd prefer doing the symlink and making it optional, so that it can be turned off in case anyone has issues with it.

[bryango]

Oh I just noticed that NixOS itself is on the list of supported systems:

system-manager/nix/modules/default.nix

Lines 139 to 145 in 549bc38

	system-manager.preActivationAssertions = {
	osVersion =
	let
	supportedIds = [ "nixos" "ubuntu" ];
	in
	{
	enable = !config.system-manager.allowAnyDistro;

So indeed it should be an option that one can toggle on or off.