Upgrade Nix

[mig4ng]

Hello, I have a some of questions:

1. Is there any specific reason not to update Nix to 2.17?
2. What is the recommended way to upgrade Nix? Following https://nixos.org/manual/nix/stable/installation/upgrading.html or using nix upgrade-nix?
3. Is it okay to run nix upgrade-nix as sudo on MacOS? It shows error: opening lock file '/nix/var/nix/profiles/default.lock': Permission denied without it.
4. Why does sudo nix upgrade-nix only updates to 2.15.1 instead of 2.17.0?

It would be nice to have a section on updating Nix with the DeterminateSystems installer. I can open a PR with it, it appears to be something like this:

---

Upgrade/Update Nix

Run the upgrade command:

nix upgrade-nix

Or, uninstall and run the installer again.

---

          Generally to upgrade Nix you should use `nix upgrade-nix` or uninstall (`/nix/nix-installer uninstall`) and reinstall.

Originally posted by @Hoverbear in #595 (comment)

[Hoverbear]

Hi! Generally nix upgrade-nix is how we suggest things. Yes this requires sudo on Mac!

nix upgrade-nix checks what the nix project has set in https://raw.githubusercontent.com/NixOS/nixpkgs/master/nixos/modules/installer/tools/nix-fallback-paths.nix to determine the version to use.

A PR to add the section you suggest would be welcome! It would fit best right below usage and above uninstalling.

[mig4ng]

Created PR, closing this.

[bestlem]

From your install etc on macos I get

sudo nix -vvvv upgrade-nix
Password:
warning: $HOME ('/Users/dev') is not owned by you, falling back to the one defined in the 'passwd' file ('/var/root')
found Nix in '/nix/store/gqf7zhkx1n6sijax727ycrm57ikrv3pc-nix-2.15.1/bin'
found profile '/nix/store/gqf7zhkx1n6sijax727ycrm57ikrv3pc-nix-2.15.1'
error: directory '/nix/store/gqf7zhkx1n6sijax727ycrm57ikrv3pc-nix-2.15.1/bin' does not appear to be part of a Nix profile

Uninstall failed as

   0: Error reverting
   0: Action `create_apfs_volume` errored
      Failed to execute command with status 1 `"/usr/sbin/diskutil" "apfs" "deleteVolume" "Nix Store"`, stdout: Started APFS operation
      Deleting APFS Volume from its APFS Container
      Unmounting disk3s7
      The volume "Nix Store" on disk3s7 couldn't be unmounted because it is in use by process 0 (kernel)

      stderr: Error: -69888: Couldn't unmount disk

OK I had a terminal open using a shell on nix so tried again and got a very long error message.

[mig4ng]

@bestlem I am not sure what is causing your error. But since you have a long error message when you tried again, share that one here as well, it might help.

I noticed after installing nix-darwin again via flakes (this experimental guide), that I am having the following error trying to upgrade:

$ sudo nix upgrade-nix
warning: $HOME ('/Users/mig') is not owned by you, falling back to the one defined in the 'passwd' file ('/var/root')
error: Nix on NixOS must be upgraded via 'nixos-rebuild'

I will reopen the issue, however, these errors seem to be unrelated to the nix-installer, so feel free to close it again.
I am keeping it open because I really like the nix-installer and it would be nice to understand what is happening and if it is at all compatible with nix-darwin or if we should avoid having both.

Edit: darwin-rebuild switch --flake ~/.config/nix-darwin (not nixos-rebuild) works to rebuild the configuration/system, but I am not sure how to upgrade the Nix version with this (or if it upgrades automatically to the pinned version e.g. #598 (comment)).

[bestlem]

Unfortunately the error was too long for github - and I have now lost it.

The issue seems to be how do you update nix and I am following your instructions.

[bestlem]

This time on a clean virtual machine sudo nix upgrade-nix change nix version from 2.15.0 to 2.15.1 with the warning that the home directory is incorrect - which I think is a sudo warning so nothing to do with nix.

The questionI have now is how do I upgrade to the latest nix which I think is 2.17?

[Hoverbear]

I believe you may have been affected by some of the issues around the nix profile location changes of that version. If you have already used nix-installer, it's probably safest to run /nix/nix-installer uninstall then remove any ~/.nix* files you might see. Reinstalling using the latest (0.11.0) version should yield Nix 2.17.

[Hoverbear]

@mig4ng documented this process so I believe this ticket is closed.