Experience using the Nix service as a novice user

[Christian Miller <christian.miller@dadoes.de>]

Hello,

I wanted to try out the Nix service and followed the manual.  I had
some trouble while doing so.  The following are the steps I took, the
errors I encountered, and how I resolved them.  As well as feedback to
the experience.


I added the nix-service-type and nix package itself according to the
Guix manual.

        (use-modules (gnu))
        (use-service-modules nix)
        (use-package-modules package-management)

        (operating-system
          ;; …
          (packages (append (list nix)
                            %base-packages))

          (services (append (list (service nix-service-type))
                            %base-services)))

                            
Those two commands are not provided by the manual.  Instead the manual
just references to the Nix manual.  It would be better to just provide
those two commands, since the Nix manual was not helpful.  This
website[0] was more helpful.
                            

        nix-channel --add https://nixos.org/channels/nixos-23.11 nixos
        nix-channel --update

        
At this point, I started encountering problems.  The command
"nix-channel --update" returns:

        unpacking channels...
        error: opening pseudoterminal master: No such device
        error: program
        '/gnu/store/mh2nc81cvw321q0lx4y38g4n7b86q88y-nix-2.16.1/bin/nix-env'
        failed with exit code 1

        
This was easy to fix because I had found this solution[1]

        sudo herd restart nix-daemon

        
Now I reran "nix-channel --update" and it worked.  After this, I was
going on with the manual which said:
        
        ln -s "/nix/var/nix/profiles/per-user/$USER/profile" ~/.nix-profile
        source /run/current-system/profile/etc/profile.d/nix.sh

        
At this point, I thought I would be done, as I had followed all the
steps in the manual.  Therefore I tried to install a package.

        nix-env --install mpv

        
However, this did not work as I encountered the following error:
        
        error: opening lock file
        '/nix/var/nix/profiles/per-user/cm/profile.lock': No such file or
        directory

        
To resolve this, I executed the following command:
        
        sudo mkdir /nix/var/nix/profiles/per-user/$USER


which resulted in another error because I forgot to set the
permissions:
        
        error: opening lock file
        '/nix/var/nix/profiles/per-user/cm/profile.lock': Permission
        denied

        
Therefore, I also executed the following command:
        
        sudo chown -R $USER:users /nix/var/nix/profiles/per-user/$USER

        
Now I could install the Nix version of mpv with

        nix-env --install mpv


I initially attempted this within a VM ($(guix system vm nix.scm) -m
4096 -smp 2) that had 4 GiB of memory and 2 cores.  The process was
terminated. Is it normal for Nix to require such a large amount of
resources to install a package?  It might be helpful to include this
information in the guide, as I was unsure whether there was a problem
with the installation or if 4 GiB of memory was insufficient.
Therefore, I tried it on my machine, which has 16 GiB of memory, and
it worked.
        
Overall, it feels not very well supported.  As a novice user, I found
the process to be quite challenging. Additionally, I was hoping for a
"working out of the box" experience, which unfortunately was not the
case with the Nix service.

[0] https://nixos.wiki/wiki/Nix_channels
[1] https://issues.guix.gnu.org/63546#7

-- 
Christian Miller