Nixpkgs: can't build nixos-unstable: ...user-environment/share/mime/packages' does not exist!

[teto]

Issue description

I am on this commit ca2ba44cab47767c8127d1c8633e2b581644eb8f

and for some reason

  /nix/store/mykr9jcwszlm4dm11b04iqzma0mm5k7k-kernel-modules-shrunk.drv
  /nix/store/cyplzyfcfj6kbwbyxj6i865k1fasihl9-stage-1-init.sh.drv
  /nix/store/bvidg730pc3dpi75a9g8v8qgh4amf4vq-initrd.drv
  /nix/store/0lqk4xkq6ymklpfz7n2m04h9w8271js1-nixos-system-jedha-19.03.git.ca2ba44cab4.drv
building '/nix/store/2vaywry475m0m3d43pq1ky6zh7z3ryn0-system-path.drv'...
building '/nix/store/sxrkq6bcm4rb17vlwjl064scsbgz9a6h-user-environment.drv'...
building '/nix/store/s78mba4n6x37s9sssfs7nx8qybh79n82-xserver.conf.drv'...
building '/nix/store/zxj2nmjzkwi2kv8jchfy6pxmkdnf0yqn-xsession.drv'...
created 42 symlinks in user environment
Directory '/nix/store/dxmg6lfqacxl5kxq52p7887xfwpnw5c3-user-environment/share/mime/packages' does not exist!
note: keeping build directory '/tmp/nix-build-user-environment.drv-3'
builder for '/nix/store/sxrkq6bcm4rb17vlwjl064scsbgz9a6h-user-environment.drv' failed with exit code 1
note: keeping build directory '/tmp/nix-build-xserver.conf.drv-3'
note: keeping build directory '/tmp/nix-build-xsession.drv-3'
cannot build derivation '/nix/store/10s3b5mr4g0mp6kr7bkxf8f67qqi33rq-etc.drv': 1 dependencies couldn't be built

I tried reverting df05618f2a075c2c727bdcb6d44741d5d5c2ef16 to no avail (as it seemed losely related).
I also removed my overlay with a similar effect.

[michaelpj]

Maybe try reverting https://github.com/NixOS/nixpkgs/pull/45058? What DE are you using?

[teto]

@michaelpj you found the culprit :D (reverting #45058 fixes it) I use i3 but it is configured/installed via home-manager so that may have thrown off some assumptions ?

[michaelpj]

Hm, I think this is a bug in that PR since it shouldn't have changed anything...

I wonder if something links /share/mime/packages and assumes the parent exists when it might not?

Not at a computer now, but will try and look later.

[michaelpj]

Could you see if applying the following patch helps?

diff --git i/nixos/modules/config/xdg/mime.nix w/nixos/modules/config/xdg/mime.nix
index a21da05370e..825fb1975a5 100644
--- i/nixos/modules/config/xdg/mime.nix
+++ w/nixos/modules/config/xdg/mime.nix
@@ -15,7 +15,10 @@ with lib;
   };

   config = mkIf config.xdg.mime.enable {
-    environment.pathsToLink = [ "/share/mime" ];
+    environment.pathsToLink = [ 
+      "/share/mime" 
+      "/share/mime/packages" 
+    ];

     environment.systemPackages = [ 
       # this package also installs some useful data, as well as its utilities 

I'll be surprised if this works, since if it does I would have expected things to be broken before (nothing linked that path previously).

[teto]

I've tried on another computer which exhibited the same error (same config so it makes sense) and applying the patch fixed it.

Naive question as I don't know that part of the code: wouln't adding "/share/mime" include "/share/mime/packages" ?

[jtojnar]

The /share/mime probably needs to be a directory instead of a symlink. Not sure how did it work before.

https://github.com/NixOS/nixpkgs/blob/d261df5fc15d41a4745e1f1482fd630d207d3f79/pkgs/build-support/buildenv/builder.pl#L34-L40

[michaelpj]

I'm a bit confused as to what we're supposed to put there. We do want /share/mime as it contains other things that should be linked, but we also want /share/mime/packages as that contains things that should be linked. Is it right to have both?

[matthewbauer]

This error comes from update-mime-database:

https://cgit.freedesktop.org/xdg/shared-mime-info/tree/update-mime-database.c#n3703

Can someone try this patch:

```
diff --git a/nixos/modules/config/xdg/mime.nix b/nixos/modules/config/xdg/mime.nix
index f1b672234a3..5b494612874 100644
--- a/nixos/modules/config/xdg/mime.nix
+++ b/nixos/modules/config/xdg/mime.nix
@@ -24,6 +24,7 @@ with lib;

 environment.extraSetup = ''
   if [ -w $out/share/mime ]; then

• mkdir -p $out/share/mime/packages
  XDG_DATA_DIRS=$out/share ${pkgs.shared-mime-info}/bin/update-mime-database -V $out/share/mime > /dev/null
  fi
  ```

[michaelpj]

That also looks plausible!

[teto]

@matthewbauer the snippet makes the problem go away as well :)

[CarlosMChica]

Hi, I'm using nixos-unstable and run into this same issue. The fix doesn't seem to be available in master yet and therefore I can't apply it by upgrading my configuration.

I've also tried overriding the original module definition with a custom one, but I couldn't figure out how to do it.

Also in the posts above people suggested applying a path to the original module, I suppose that implies maintaining a "custom" version of nixpkgs to which we can apply changes on top?

I'm fairly new to nix, so please excuse me if the questions are silly. Thanks

[teto]

Also in the posts above people suggested applying a path to the original module, I suppose that implies maintaining a "custom" version of nixpkgs to which we can apply changes on top?

If you are going to stick with nix, having a local checkout is the way to go. I have my own nixos-unstable with some patches on top of the official nixos-unstable so I cherrypicked the change. An alternative is to rollback/use previous generations.

[CarlosMChica]

Thanks for the quick response, really appreciate it.

I will try that, thanks! Do you have by any chance a link that explain how to do this setup? I just had a quick looking around in the nixpkgs documentation but couldn't find it, anyway I will investigate this further later today. Thanks once again!

[teto]

https://nixos.wiki/wiki/Nixpkgs/Create_and_debug_packages
https://nixos.org/nix-dev/2015-March/016489.html
basically you can set nix.nixPath in your configuration.nix to have nixpkgs point at your local repository.
Or you can manually specify it in most nix commands via -I nixpkgs=/home/carlos/nixpkgs

[CarlosMChica]

Fantastic.

Thank you so much for your help, very much appreciated!