Confirmed working with #14372 using the following config files for an external opengl:

packages.yaml

---
packages:
  opengl:
    paths:
      [email protected]+egl+glx+glvnd: /usr
    variants: +glvnd+egl+glx
    buildable: False

modules.yaml

---
modules:
  tcl:
    [email protected]+glx+glvnd:
      environment:
        set:
          __GLX_VENDOR_LIBRARY_NAME: nvidia
    [email protected]+egl+glvnd:
      environment:
        set:
          __EGL_VENDOR_LIBRARY_FILENAMES: /usr/share/glvnd/egl_vendor.d/10_nvidia.json

Confirmed working with #14372

Marked as dont-merge-yet until the necessary dependent feature is merged.

modules.yaml

---
modules:
  tcl:
    [email protected]+glx+glvnd:
      environment:
        set:
          __GLX_VENDOR_LIBRARY_NAME: nvidia
    [email protected]+egl+glvnd:
      environment:
        set:
          __EGL_VENDOR_LIBRARY_FILENAMES: /usr/share/glvnd/egl_vendor.d/10_nvidia.json

So, this is interesting. Would there be two different entries? It seems like that would give two different specs and that you might just have a single entry:

modules.yaml

---
modules:
  tcl:
    [email protected]+egl+glx+glvnd:
      environment:
        set:
          __EGL_VENDOR_LIBRARY_FILENAMES: /usr/share/glvnd/egl_vendor.d/10_nvidia.json
          __GLX_VENDOR_LIBRARY_NAME: nvidia

@chuckatkins my understanding is that these entries are not mutually exclusive. The way to read my modules.yaml is "If the current module being generated is for a package that matches [email protected]+glx+glvnd (i.e.: opengl 4.5 with glx through libglvnd), add the following __GLX variable." And then subsequently: "If the current module being generated is for a package that matches [email protected]+egl+glvnd (i.e.: opengl 4.5 with egl through libglvnd), add the following __EGL variable." An opengl with both +glx and +egl through +glvnd would match both entries and have both variables added to its module.

EDIT: Of course, your suggestion would work fine, too, if you only ever dealt with opengl specs that had both +glx and +egl (with +glvnd).

@opadron I tried to rebase this branch locally on f396106 and this is the module I get using the configs mentioned at #14572 (comment):

#%Module1.0
## Module file created by spack (https://github.com/spack/spack) on 2020-02-18 18:35:40.269362
##
## [email protected]%[email protected]+egl+glvnd+glx arch=linux-ubuntu18.04-broadwell/hflpxtp
##
## Configure options: unknown, software installed outside of Spack
##


module-whatis "Placeholder for external OpenGL libraries from hardware vendors"

proc ModulesHelp { } {
puts stderr "Placeholder for external OpenGL libraries from hardware vendors"
}


prepend-path MANPATH "/usr/share/man"
prepend-path ACLOCAL_PATH "/usr/share/aclocal"
prepend-path PKG_CONFIG_PATH "/usr/lib/pkgconfig"
prepend-path PKG_CONFIG_PATH "/usr/share/pkgconfig"
setenv __GLX_VENDOR_LIBRARY_NAME "nvidia"
setenv __EGL_VENDOR_LIBRARY_FILENAMES "/usr/share/glvnd/egl_vendor.d/10_nvidia.json"

It seems fine to me.

@alalazo I cannot reproduce this behavior on the latest spack/centos7 image. I've tried both develop and this branch rebased on develop.

Are you using lmod for modules? The docker image uses that instead of TCL modules.

EDIT: In particular, I cannot get Spack to add any environment variables to any generated modules. I've tried opengl and simple packages like zlib.

spack --version

0.13.4-1177-4e1cbd7

@chuckatkins PTAL. I still need to rebase, but the necessary changes should be there.

Rebased.

It looks like this was good to go prior to rebasing but something got borked in the rebase. Rather than churning through the things that got left out, we're going to revert this and re-introduce the change set based on develop head.