Boost includes missing in FHS environment

dsxmachina · August 13, 2020, 12:59pm

Hello,

i have troubles getting a project of mine to work in nixos, so as a last resort I wanted to use a FHS-User environment for that project.
Since it is a cuda project, I used the FHSUserEnvironment example from here:
https://nixos.wiki/wiki/Nvidia

But in addition, i also need the boost library, so i added it to the targetPkgs set

targetPkgs = pkgs: with pkgs; [ ... boost167 ...];

This puts the libboost_*.so libraries under /usr/lib,
but the header files are missing !

I read about boost being a split package, and maybe it has something to do with that,
but I can’t figure out how I could fix that.

Does anybody has an idea ?
Thanks!

jtojnar · August 13, 2020, 1:41pm

dsxmachina · August 14, 2020, 10:51am

Nice! That was it!
Where did you find that piece of information ?
I thought I went carefully enough through the nixpkgs manual

Thanks anyway!

jtojnar · August 14, 2020, 6:07pm

The fact that only some parts of the package are included pointed out it is likely caused by multiple outputs.

I usually prefer looking at the source code since I often find it easier to scan through than human writing so I looked at the source for fhs userenv (greping for buildFHSUserEnv =) and noticed:

github.com

NixOS/nixpkgs/blob/3cc42af71fab4695324d08b8b866a12ffb16a400/pkgs/build-support/build-fhs-userenv/env.nix#L6


      
          { stdenv, buildEnv, writeText, pkgs, pkgsi686Linux }:
          
          
{ name, profile ? ""
          , targetPkgs ? pkgs: [], multiPkgs ? pkgs: []
          , extraBuildCommands ? "", extraBuildCommandsMulti ? ""
          , extraOutputsToInstall ? []
          }:
          
          
# HOWTO:
          # All packages (most likely programs) returned from targetPkgs will only be
          # installed once--matching the host's architecture (64bit on x86_64 and 32bit on
          # x86).
          #
          # Packages (most likely libraries) returned from multiPkgs are installed
          # once on x86 systems and twice on x86_64 systems.
          # On x86 they are merged with packages from targetPkgs.

looking at how it is used

github.com

NixOS/nixpkgs/blob/3cc42af71fab4695324d08b8b866a12ffb16a400/pkgs/build-support/build-fhs-userenv/env.nix#L125


      
          
          
    # symlink /etc/mtab -> /proc/mounts (compat for old userspace progs)
              ln -s /proc/mounts mtab
            '';
          };
          
          
# Composes a /usr-like directory structure
          staticUsrProfileTarget = buildEnv {
            name = "${name}-usr-target";
            paths = [ etcPkg ] ++ basePkgs ++ targetPaths;
            extraOutputsToInstall = [ "out" "lib" "bin" ] ++ extraOutputsToInstall;
            ignoreCollisions = true;
          };
          
          
staticUsrProfileMulti = buildEnv {
            name = "${name}-usr-multi";
            paths = baseMultiPkgs ++ multiPaths;
            extraOutputsToInstall = [ "out" "lib" ] ++ extraOutputsToInstall;
            ignoreCollisions = true;
          };

lead me to buildEnv, which confirmed my suspicion:

github.com

NixOS/nixpkgs/blob/3cc42af71fab4695324d08b8b866a12ffb16a400/pkgs/build-support/buildenv/default.nix#L59-L69


      
          # First add the usual output(s): respect if user has chosen explicitly,
          # and otherwise use `meta.outputsToInstall`. The attribute is guaranteed
          # to exist in mkDerivation-created cases. The other cases (e.g. runCommand)
          # aren't expected to have multiple outputs.
          (if drv.outputUnspecified or false
              && drv.meta.outputsToInstall or null != null
            then map (outName: drv.${outName}) drv.meta.outputsToInstall
            else [ drv ])
          # Add any extra outputs specified by the caller of `buildEnv`.
          ++ lib.filter (p: p!=null)
            (builtins.map (outName: drv.${outName} or null) extraOutputsToInstall);

jtojnar · August 14, 2020, 6:08pm

Thought the argument is actually mentioned in the manual: Nixpkgs 23.11 manual | Nix & NixOS

dsxmachina · August 16, 2020, 10:09am

Thanks for describing the process to me!