[Nix-dev] Newbie experiences with NixOS

[Gergö Barany]

Hi everyone,

this is a long mail about some of the issues I ran into when I recently
tried to install NixOS 14.04 on my home machine (which is mostly for "fun"
and some software development, but not a server). I ended up not using NixOS
for various reasons; I'm trying to give useful feedback, and I hope I will
succeed in not making this read like a rant full of complaints and demands.

I'm happy to file bug reports for some of the issues mentioned below, but
I'm not always sure what project to file them on. Should every one of the
problems with configuration.nix/nixos-rebuild be reported against nixpkgs,
even if might not actually concern a package definition?

My background, briefly: I've been using Linux for about 15 years now, on
various distributions. I know much of what I need for system administration,
but I hate actually having to tweak system stuff. I know various pure and
impure functional and logic programming languages, but the Nix language is a
mystery to me...

So, here goes. First some very minor comments on the website and the manual,
then more serious issues I ran into when trying (and failing) to install
some packages I wanted.


Website and the manual:

- I found it confusing that the manual talks about adding users imperatively
  and imperative package management very early on. Not a problem, I'm just
  wondering why it does this in the middle of explaining how to set up a
  nice *declarative* system.

- I found it puzzling that the package channel is to be set imperatively on
  the command line rather than in the configuration file. This breaks the
  nice property of the entire configuration being in one or more config
  files.

- In the manual, it would be nice to have Appendix B avaiable as a single
  HTML page separate from the rest of the manual. (Told you these were
  minor comments.) That would make full-text search for some options easier.

- The installation live CD comes with Konqueror as its web browser. The
  JavaScript of the package browser at http://nixos.org/nixos/packages.html
  does not work in Konqueror! Did not work for me at least, and there is no
  fallback to a simpler search page.
  (I guess I should file this as a bug?)


Configuration:

- I haven't gone very deep here, but if I add a user in configuration.nix
  and do nixos-rebuild, and then modify the configuration to add extraGroups
  (such as wheel) for that user and run nixos-rebuild --switch again, then
  the extra group setting just seems to be ignored; the user is not added to
  the group.
  (Would it be OK to file this as a bug against nixpkgs? If not, what github
  project should it be?)


Package installation:

- ghc. I didn't care about the exact version, just hoped that a
  "meta-package" named "ghc" would work. Here's a complete config file I
  tried:

{ config, pkgs, ... }:
{
  imports = [ ./hardware-configuration.nix ];
  boot.loader.grub.enable = true;
  boot.loader.grub.version = 2;
  boot.loader.grub.device = "/dev/sda";
  services.xserver.enable = true;
  services.xserver.displayManager.kdm.enable = true;
  services.xserver.desktopManager.kde4.enable = true;

  environment.systemPackages = with pkgs; [
    wget vim
    ghc
  ];
}

When running "nixos-rebuild build" on this, it failed with:
error: cannot coerce a set to a string, at /nix/var/nix/profiles/per-user/root/channels/nixos/nixpkgs/lib/types.nix:98:79

Needless to say, I never touched that file. If I recall correctly,
specifying a *concrete* ghc package name did work. Using a generic name
imperatively worked: "nix-env -i ghc" selects a derivation automagically and
installs it.


- clementine (a music player). The issue here was that by default it depends
  on the unfree libspotify package, but there is an option to install it
  without this library. However, it didn't work for me:

{ config, pkgs, ... }:
{
  imports = [ ./hardware-configuration.nix ];
  boot.loader.grub.enable = true;
  boot.loader.grub.version = 2;
  boot.loader.grub.device = "/dev/sda";
  services.xserver.enable = true;
  services.xserver.displayManager.kdm.enable = true;
  services.xserver.desktopManager.kde4.enable = true;

  config.clementine.spotify = false;
  environment.systemPackages = with pkgs; [
    wget vim
    clementine
  ];
}

Trying to build this fails with:
error: Module `/etc/nixos/configuration.nix' has an unsupported attribute `boot'.

This appears to be some sort of internal error in nixos-rebuild, maybe with
parsing the config file?


- swt (a Java GUI toolkit, needed by some Java programs). Trying to install
  this (with a config file as above, only with "swt" in the package list)
  tries to download http://eclipse.ialto.com/eclipse/downloads/drops/R-3.7.2-201202080800/swt-3.7.2-gtk-linux-x86.zip
  and fails, since that file (and the directory it is supposed to be in)
  doesn't exist. A file with that name is available from a more official
  source at
  http://www.eclipse.org/downloads/download.php?file=/eclipse/downloads/drops/R-3.7.2-201202080800/swt-3.7.2-gtk-linux-x86.zip
  I tried remounting the package store read-write and copying this file to
  the expected place, but the installer didn't pick it up from there, it
  tried the broken mirror again. Is there a way to inject a manually
  downloaded file into the build process, or to specify another download
  URL, short of modifying the Nix expression for the package?


These are not terrible show-stoppers, I could somehow work around each of
them. However, for me personally, I decided that NixOS was slightly too
immature at the moment, because I really don't enjoy solving this kind of
system administration problems. That said, I will keep an eye on it and keep
playing with it in a virtual machine, and if requested, I'll be happy to
complain more :-)

Keep up the good hard work!


Gergo