installed apps don’t show up in Ubuntu's "Show Applications"

[samuela]

Issue description

Apps installed via home-manager don't show up in the Ubuntu "Show Applications" thingy.

See https://discourse.nixos.org/t/home-manager-installed-apps-dont-show-up-in-applications-launcher/8523 for context. https://github.com/rycee/home-manager/blob/master/modules/misc/xdg-mime.nix suggests that home-manager should be adding these applications to the desktop manager database automatically, but for some reason it's not working. Note that running update-desktop-database manually on a copy of the relevant stuff in the nix store does work, as discussed in the Discourse thread.

I have targets.genericLinux.enable = true and verified that $XDG_DATA_DIRS is being set appropriately:

❯ echo $XDG_DATA_DIRS
/nix/var/nix/profiles/default/share:/home/skainswo/.nix-profile/share:/home/skainswo/deleteme:/home/skainswo/.nix-profile/share/applications:/home/skainswo/.nix-profile/share/applications:/home/skainswo/.nix-profile/share/applications:/usr/share/ubuntu:/usr/local/share/:/usr/share/:/var/lib/snapd/desktop

Here's the entirety of my home.nix: https://gist.github.com/samuela/b507cb3a3effde6117b32700add2f448. I'm running Ubuntu 20.04.

Meta

Maintainer CC

@rycee @Kha

Technical details

❯ nix-shell -p nix-info --run "nix-info -m"
 - system: `"x86_64-linux"`
 - host os: `Linux 5.4.0-42-generic, Ubuntu, 20.04.1 LTS (Focal Fossa)`
 - multi-user?: `no`
 - sandbox: `yes`
 - version: `nix-env (Nix) 2.3.7`
 - channels(skainswo): `"home-manager, nixpkgs-20.09pre237891.f9eba87bf03"`
 - nixpkgs: `/home/skainswo/.nix-defexpr/channels/nixpkgs`

[rycee]

Could you share the output of

$ ls ~/.nix-profile/share/applications

?

[samuela]

Sure!

❯ ls ~/.nix-profile/share/applications  
code-url-handler.desktop  htop.desktop    transmission-gtk.desktop
code.desktop              mimeinfo.cache  virt-manager.desktop
emacs.desktop             slack.desktop   vlc.desktop

[samuela]

No idea if this is related but when I run a home-manager switch I get this message:

Activating reloadSystemD
The user systemd session is degraded:
  UNIT                           LOAD   ACTIVE SUB    DESCRIPTION                               
● xdg-desktop-portal-gtk.service loaded failed failed Portal service (GTK+/GNOME implementation)

LOAD   = Reflects whether the unit definition was properly loaded.
ACTIVE = The high-level unit activation state, i.e. generalization of SUB.
SUB    = The low-level unit activation state, values depend on unit type.

[Kha]

I'm not using Gnome unfortunately. But you said that the launcher works if you call update-desktop-database yourself in a separate directory? Do you see any relevant difference between the cached generated by that and ~/.nix-profile/share/applications/mimeinfo.cache?

[samuela]

Ok, I did the following:

$ cd
$ mkdir -p deleteme/applications

Then added export XDG_DATA_DIRS="/home/skainswo/deleteme:$XDG_DATA_DIRS" to the end of my ~/.profile.

$ echo $XDG_DATA_DIRS                               
/nix/var/nix/profiles/default/share:/home/skainswo/.nix-profile/share:/home/skainswo/deleteme:/usr/share/ubuntu:/usr/local/share/:/usr/share/:/var/lib/snapd/desktop
$ cp ~/.nix-profile/share/applications/* ~/deleteme/applications
$ update-desktop-database -v ~/deleteme/applications
Search path is now: [/home/skainswo/deleteme/applications]
File "/home/skainswo/deleteme/applications/htop.desktop" lacks MimeType key
File "/home/skainswo/deleteme/applications/virt-manager.desktop" lacks MimeType key
$ diff deleteme/applications/mimeinfo.cache ~/.nix-profile/share/applications/mimeinfo.cache
$ 

Then logging in and logging out I can see that I have all the apps in "Show Applications". So they actually have the same mimeinfo.cache. Here's its contents: https://gist.github.com/samuela/4ed9677cf522f26d806408f34caaeb35.

[samuela]

Update: it seems that in order to get rid of shortcuts after editing .profile a logout isn't sufficient, but a restart works.

[samuela]

Update 2: Adding

export XDG_DATA_DIRS="/home/skainswo/.nix-profile/share:$XDG_DATA_DIRS"

to my ~/.profile and restarting does work! So my guess is that home-manager is inserting its stuff into $XDG_DATA_DIRS too late for them to get picked up properly by Unity/GNOME/whatever.

[Kha]

I see, you only have programs.zsh.enable set, not programs.bash.enable. The latter would update your .profile appropriately. I'm actually using the same settings, but since I start my window manager from a zsh login shell, the environment variables are still loaded.

[samuela]

Mm, I see. So I guess home-manager should still be adding some things to .profile even when programs.bash.enable = false then?

[cideM]

So I tried looking into this as well because for me home manager installed icons only work on NixOS but not on Arch.

As you can see, I have the spotify icon in my nix-profile folder, and XDG_DATA_DIRS includes that folder. So as far as I can tell, it should see the icons folder because XDG_DATA_DIRS includes the root path containing that icons folder. But since some folks in this thread mentioned this update-desktop-database which doesn't work because immutable I guess that that's the problem?

For me restarts don't help.

cloud $ echo $XDG_DATA_DIRS | string split ":"
/nix/var/nix/profiles/default/share
/home/cloud/.nix-profile/share
/home/cloud/.nix-profile/share
/home/cloud/.local/share/flatpak/exports/share
/var/lib/flatpak/exports/share
/usr/local/share
/usr/share
cloud $ fd . -t l ~/.nix-profile/share/icons/ | rg spotify
/home/cloud/.nix-profile/share/icons/hicolor/128x128/apps/spotify-client.png
/home/cloud/.nix-profile/share/icons/hicolor/16x16/apps/spotify-client.png
/home/cloud/.nix-profile/share/icons/hicolor/256x256/apps/spotify-client.png
/home/cloud/.nix-profile/share/icons/hicolor/32x32/apps/spotify-client.png
/home/cloud/.nix-profile/share/icons/hicolor/48x48/apps/spotify-client.png
/home/cloud/.nix-profile/share/icons/hicolor/512x512/apps/spotify-client.png
/home/cloud/.nix-profile/share/icons/hicolor/64x64/apps/spotify-client.png

 - system: `"x86_64-linux"`
 - host os: `Linux 5.8.1-arch1-1, Arch Linux, noversion`
 - multi-user?: `no`
 - sandbox: `yes`
 - version: `nix-env (Nix) 2.3.7`
 - channels(cloud): `"home-manager, nixpkgs-20.09pre235385.ca4e665f8c3, nixos-20.03-20.03.2611.bb8f0cc2279"`
 - nixpkgs: `/home/cloud/.nix-defexpr/channels/nixpkgs`

[Kha]

As you can see, I have the spotify icon in my nix-profile folder, and XDG_DATA_DIRS includes that folder.

This doesn't guarantee that your DE uses the same values. You could look in /proc/$pid/environ where $pid is the process ID of the launcher to make sure.

But since some folks in this thread mentioned this update-desktop-database which doesn't work because immutable I guess that that's the problem?

Home manager calls update-desktop-database during build for you, then links the resulting store path, which as usual is immutable, into your home. You are not supposed to call it yourself, but you can inspect the files produced by Home manager to make sure they are correct. But again, I don't know what data exactly Gnome or other DEs expect there. I only cared about xdg-open in the shell working.

[cideM]

This doesn't guarantee that your DE uses the same values. You could look in /proc/$pid/environ where $pid is the process ID of the launcher to make sure.

That's a great tip, I didn't know about this. I took the parent process for /usr/bin/gnome-shell which spawns a couple of other gnome-shell threads and then checked its environ:

XDG_DATA_DIRS=/home/cloud/.local/share/flatpak/exports/share:/var/lib/flatpak/exports/share:usr/local/share:/usr/share

Indeed, the Home Manager file paths are missing here. I did some more specific googling and came upon a very interesting Gnome issue filed by a Guix user. On another tracker the issue has a solution and some more instructions specifically for distros like Arch which have this issue can be found here

Unfortunately I couldn't make it work so far. I tried adding export XDG_DATA_DIRS to /etc/profile but that didn't help. .profile and .config/systemd/ also didn't help. I'll ask around in some Arch Linux/GNOME circles as to how I can set XDG_DATA_DIRS for the first /usr/bin/gnome-shell process that's started

[rajibahmed]

Me and @terlar was working with this issue for popOS (ubuntu based). the solution so far we found . setting home.nix like this. When the homeSession variables are passed to pamSession then the *.desktop files are found.

Still couldn't fix the pop-shell launcher, desktop apps are not searchable by super + /

xdg = {
   enable = true;
 };
 home.sessionVariables = {
   EDITOR="nvim";
   BROWSER = "firefox";
   TERMINAL = "alacritty";
 };

 pam.sessionVariables = config.home.sessionVariables // {
      LANGUAGE	="en_US:en";
      LANG	="en_US.UTF-8";
     //copy your pam session stuff here  from ~/.pam_environment
 };