Feature request: --delete-generations with --keep-booted #723

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opened 2025-03-10 17:35:07 +00:00 by jbgi · 1 comment

jbgi commented

2025-03-10 17:35:07 +00:00

From time to time I notice that I lost my currently booted generation when nix-env --delete-generationsing, because I had so many nixos-rebuild switch in between that I removed the old ones (I usualy keep 5-10 generations).

It would be a nice feature to have a flag to remove generations, but keep the currently booted one (as one can be sure that it works).

Describe the solution you'd like

--keep-booted flag (for nix-env and nic-collect-garbage) that would prevent deleting any /nix/var/nix/profiles/system-*-link symlink that would point to the same as /run/booted-system

Even better (but would break current behavior) would be that --keep-booted would be default behavior (so no need to add flag). Because I don't see any any drawback to always keep it (since it's a gc root anyway)

Additional context

Port of https://github.com/NixOS/nix/issues/1095

## Is your feature request related to a problem? Please describe. From time to time I notice that I lost my currently booted generation when nix-env --delete-generationsing, because I had so many nixos-rebuild switch in between that I removed the old ones (I usualy keep 5-10 generations). It would be a nice feature to have a flag to remove generations, but keep the currently booted one (as one can be sure that it works). ## Describe the solution you'd like `--keep-booted` flag (for `nix-env` and `nic-collect-garbage`) that would prevent deleting any `/nix/var/nix/profiles/system-*-link` symlink that would point to the same as `/run/booted-system` Even better (but would break current behavior) would be that `--keep-booted` would be default behavior (so no need to add flag). Because I don't see any any drawback to always keep it (since it's a gc root anyway) ## Additional context Port of https://github.com/NixOS/nix/issues/1095

pennae commented

2025-03-10 17:52:51 +00:00

Owner

that's not a problem lix can solve but something nixos must do. --keep-booted absolutely not going to happen because it's overly specific and ill-defined. the better option here would be for nixos to add a second profile (booted-system or something) and updating it only on reboots, which will both solve your immediate problem and possibly even give you a booted-generation log for times when you know that reboot three generations ago worked fine. you could even add such generation maintenande in an activation script.

that's not a problem lix can solve but something nixos must do. `--keep-booted` absolutely not going to happen because it's overly specific and ill-defined. the better option here would be for nixos to add a second profile (`booted-system` or something) and updating it only on reboots, which will both solve your immediate problem *and* possibly even give you a booted-generation log for times when you know that reboot three generations ago worked fine. you could even add such generation maintenande in an activation script.