Should services in `nixos-rebuild build-vm` work?

[MichaelBergquistSuarez]

I'm using home-manager release-19.03 as a nixos module.

But after nixos-rebuild build-vm --fast && ./result/bin/run-*-vm and logging in to my user, xmonad won't start.

I'm not yet 100% sure how to troubleshoot it, but before I continue my troubleshooting journey I thought I'd ask:

Is the xmonad module this is expected to work with build-vm?

---

I am uncertain because in news.nix, 2018-02-06, it says:

For example, it is currently not possible to use 'nixos-rebuild build-vm' when using the Home Manager NixOS module

But since then this have been added to the documentation:

Note By default packages will be installed to $HOME/.nix-profile but they can be installed to /etc/profiles if

home-manager.useUserPackages = true;

is added to the system configuration. This is necessary if, for example, you wish to use nixos-rebuild build-vm. This option may become the default value in the future.

Which I interpret as build-vm now is expected to work, but maybe I'm wrong? Or is it likely that there's something wrong with my setup?

Notes

• Any tips on how I can troubleshoot this is appreciated

• nixos-rebuild test and nixos-rebuild switch works as expected, but I can't remember if I have made manual changes outside of my configuration.nix.

• sudo systemctl status display-manager shows active status.

• Related xmonad home-manager options

  ```nix { config, pkgs, ... }: { home = { packages = [ pkgs.haskellPackages.xmobar ]; }; xsession.windowManager.xmonad = { config = ./xmonad.hs; enable = true; enableContribAndExtras = true; extraPackages = haskellPackages: [ haskellPackages.taffybar haskellPackages.xmobar haskellPackages.xmonad haskellPackages.xmonad-contrib haskellPackages.xmonad-extras ]; }; } ```
• Related xmonad nixos options

  ```nix { imports = [ "${home-manager}/nixos" ]; home-manager = { useUserPackages = true; users.my-user = import ./home-manager-config; }; services = { xserver = { autorun = true; enable = true; displayManager = { slim.enable = false; lightdm.enable = true; }; windowManager = { default = "xmonad"; xmonad.enable = true; # Each user uses home manager to configure xmonad }; }; }; users.extraUsers.my-user = { description = "My user"; isNormalUser = true; extraGroups = [ "wheel" ]; } # I also do this in another `vm-config.nix` file used only by the vm. Could this affect somehow? users.extraUsers.my-user.initialPassword = "a-password"; } ```

[rycee]

Yeah, it should work. Did you also set xsession.enable = true;? Without this the xsession would not be generated.

[MichaelBergquistSuarez]

Thank you, I did manage to get it up and running!

The suggested option did have an effect (things looked a bit better, a background image showed up) but still no xmonad

Since it should have worked I continued with my throubleshooting

It was not a home-manager problem, so this issue can be closed, sorry for taking up time. I'll pay it back by explaining how I did if somebody from the future has similar problems:)

• systemctl status home-manager-michael told me that Home Manager Service failed to start with error messages such as collect2: ld terminated with signal 9 [Killed] and compilation terminated, which could indicate memory problems.
• dmesg seemed to confirmed that with Out of memory: Kill process 1374 (ld) score 409 or sacrifice child.
• free --mega showed me that the VM had very little memory.

This was my first Nixos VM build so I didn't know what the defaults were or how to change them. I then found options not very well documented in a chat: virtualisation.virtualisation and virtualisation.memorySize.

So I gave them a higher value, and then it simply worked, hooray