Best way to define common FHS environment?

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1

I have the following definition in my systemPackages, which gives me an fhs binary which drops me into a shell which looks like a normal Linux:

  environment.systemPackages = with pkgs; [
    (pkgs.buildFHSUserEnv {
      name = "fhs";
      targetPkgs = pkgs: with pkgs; [
        alsa-lib atk cairo cups curl dbus expat file fish fontconfig freetype
        fuse glib gtk3 libGL libnotify libxml2 libxslt netcat nspr nss openjdk8
        openssl.dev pango pkg-config strace udev vulkan-loader watch wget which
        xorg.libX11 xorg.libxcb xorg.libXcomposite xorg.libXcursor
        xorg.libXdamage xorg.libXext xorg.libXfixes xorg.libXi xorg.libXrandr
        xorg.libXrender xorg.libXScrnSaver xorg.libxshmfence xorg.libXtst
        xorg.xcbutilkeysyms zlib fontconfig.lib
      ];
      profile = ''export FHS=1'';
      runScript = "fish";
    })
    # all of my other packages
  ];

$ ls /usr/lib
"/usr/lib": No such file or directory (os error 2)

$ fhs

(fhs) $ ls /usr/lib | head -n 5
dr-xr-xr-x   - nobody  1 Jan  1970 32
dr-xr-xr-x   - nobody  1 Jan  1970 audit
dr-xr-xr-x   - nobody  1 Jan  1970 bash
dr-xr-xr-x   - nobody  1 Jan  1970 cairo
lrwxrwxrwx  69 nobody  1 Jan  1970 crt1.o -> /nix/store/aji28kaprqnrkapmfyjnnnv3ffvlaq0a-fhs-usr-target/lib/crt1.o
(fhs) $ # I can now run various unpatched vanilla binaries here

It works great, except that there’s this frightening block of standard packages which I partially copied from somewhere, and partially append a bunch of random stuff myself.

Is there some maintained-by-someone-else package I can re-use here? I am essentially looking for buildFHSUserEnv specialized to a set of “standard” packages (whatever that set is at the current moment in time).

2 Likes
2

I’m not aware of any standard set of packages, but something like this can include most of what you want

builtins.concatMap (p: p.buildInputs) config.environment.systemPackages
1 Like
3

I’m not super familiar with it, but I think there are various lists of packages for use with buildfhsuserenvs in nixpkgs.

For instance:

Used here for example (I think):

3 Likes
4

Thanks, this is exactly what I was looking for!

1 Like
5

I wanted to share this little script:

nix shell --impure --expr '(builtins.getFlake "nixpkgs-current").legacyPackages.${builtins.currentSystem}.buildFHSUserEnv { name = "fhs"; targetPkgs = p: with p; ['"$*"' ]; }' --command fhs

Arguments accepted are simply packages. This can also be improved to include support for additional arguments to the shell itself etc…

1 Like
6

Thank you so much for this solution, it’s been a huge help in setting up a development shell with Nix flakes.

If this can help someone else, here’s how I’ve used it in flake.nix:

{
  description = ".NET development environment based on the Filesystem Hierarchy Standard (FHS)";
  # https://en.wikipedia.org/wiki/Filesystem_Hierarchy_Standard

  inputs = {
    nixpkgs.url = "github:nixos/nixpkgs?ref=nixos-unstable";
  };

  outputs = { nixpkgs, ... } @ inputs:
  let
    system = "x86_64-linux";
    pkgs = nixpkgs.legacyPackages.${system};

    # .NET SDKs
    dotnet_sdk = (with pkgs.dotnetCorePackages; combinePackages [
      # Install all the .NET SDK versions needed here...
      # sdk_8_0
      # sdk_7_0
      sdk_6_0
    ]);
  in
  {
    # Create development shell based on the Filesystem Hierarchy Standard (FHS) with a set of
    # standard packages based on the list maintained by the appimagetools package
    #
    # buildFHSEnv -> https://nixos.org/manual/nixpkgs/stable/#sec-fhs-environments
    #
    # The packages included in appimagetools.defaultFhsEnvArgs are:
    # https://github.com/NixOS/nixpkgs/blob/fd6a510ec7e84ccd7f38c2ad9a55a18bf076f738/pkgs/build-support/appimage/default.nix#L72-L208
    devShells.${system}.default = (pkgs.buildFHSEnv (pkgs.appimageTools.defaultFhsEnvArgs // {
          name = "dotnet-development-environment";
          # Packages installed in the development shell
          targetPkgs = pkgs: with pkgs; [
            # .NET SDK
            dotnet_sdk
            # Run PowerShell scripts, which are sometimes included in NuGet packages like Playwright
            powershell
            # Timezones
            tzdata
            # Locales
            glibcLocales
          ];
          # Commands to be executed in the development shell
          profile = ''
            # Ensure that dotnet tools can find the .NET location
            export DOTNET_ROOT="${dotnet_sdk}";

            # Set LANG for locales, otherwise it is unset when running "nix-shell --pure"
            export LANG="C.UTF-8"

            # Remove duplicate commands from Bash shell command history
            export HISTCONTROL=ignoreboth:erasedups

            # Do not pollute $HOME with config files (both paths are ignored in .gitignore)
            export DOTNET_CLI_HOME="$PWD/.net_cli_home";
            export NUGET_PACKAGES="$PWD/.nuget_packages";

            # Put dotnet tools in $PATH to be able to use them
            export PATH="$DOTNET_CLI_HOME/.dotnet/tools:$PATH"
          '';
        })).env;
  };
}
1 Like