SPACK
Building user software

General information

With the change to RHEL 9 , we also start using SPACK for building our central module system available for all users.

SPACK has the advantage of allowing users to quickly build their own software packages themselves (if the package is supported, see “spack list <name>”).

As the systemwide spack settings initially point to the read-only central installation, some of these settings have to be changed in order for users to build their own software via spack.

There are two ways: a custom spack “environment”, or user specific config files in ~/.spack/ .

We recommend using an environment as listed below.

Creating:

 spack env create <$HOME/path/to/environment>

For example, to create an environment named “My_Env” in your home directory:

 spack env create $HOME/My_Env

or (if you already are in that directory):

 spack env create .

For example:

 mkdir -p $HOME/My_Env
 cd My_Env
 spack env create .

Please, notice that you need to provide a path. If you provide just a directory name, Spack will interpret it as a so called “managed environment”, leading to an error, because in this case the directory for the environment should be created in a subdirectoy of the Spack installation, which is in a read-only file system.

Activating:

You can enable your environment with 

 spack env activate <$HOME/path/to/environment>

or using its symbolic name:

 spack env activate My_Env

Instead of “spack env activate”, you can also use the shorter alias “spacktivate”.

Deactivate

To leave the environment and return to the default settings, use 

 spack env deactivate

(or shorter: “despacktivate”)

which will reduce your available modules again to those in the central SPACK module system.

Important notice!

Before deactivating an environment, all packages loaded with “spack load <package name>” must be unloaded with “spack unload <package name>”, otherwise the working environment may become cluttered and many programs unusable.

SPACK Environment Config

Inside the environment you need to change some config settings. You can do this with “spack config edit”, or by editing the <$HOME/path/to/environment>/spack.yaml file with a text editor of your choice.

The config should be changed to look like this (comments “#…” can be left out):

Environment spack.yaml 

# This is a Spack Environment file.
#
# It describes a set of packages to be installed, along with
# configuration settings.
spack:
##### Config Settings #####
  config:
    install_tree:
      root: ~/myspackapps
    build_jobs: 16
    build_stage:
    - $tempdir/$user/spack-stage
    - $user_cache_path/stage
    test_stage: $user_cache_path/test
    source_cache: ~/packapps/cache
    misc_cache: $user_cache_path/cache
  packages:
    all:
      permissions:
        read: group
        write: group
        group: <YOUR USERID/TUID> # alternatively the GROUPID related to a project dir you want to use, need to change install_tree, too
    gcc:
      buildable: true
    llvm:
      buildable: true
    intel-oneapi-compilers:
      buildable: true
  upstreams:
    spack-instance-1:
      install_tree: /shared/spapps
      modules:
        lmod: /shared/spmodules
  
##### Config Settings End #####

  # add package specs to the `specs` list
  specs: []
  
  view: false
  concretizer:
    unify: when_possible
    reuse: true
Please replace anything within <…> with your own values!

SPACK env is “additive”

With this configuration of an own SPACK “environment” (see “upstreams:”), you activate your own software in addition to all modules from the central SPACK module system – it will not be masked or inactivated.

Software modules via SPACK

You can then add your software packages (in SPACK speak “specs”) to your environment as you wish.

Either use the spack command -

 spack add gcc@8 %gcc@11.4.1

or – before “activating it” – manually edit the <$HOME/path/to/environment>/spack.yml file accordingly, followed then by “spacktivate”.

To build (= compile + install) all specs added to your environment, use 

 spack install

or to just build a certain spec: 

 spack install gcc@8 %gcc@11.4.1

What's this @ and %:

The Spack syntax with “@” and “%” means here:

  • software@version = create this software package in exactly this version
  • %compiler@version = using this compiler in exactly its version given

With a “:” (colon), you can also specify “from-to ranges” for versions:

  • software@1:3 = create either version 1, 2 or 3 of “software”.

If you omit the “@version” part altogether, Spack will use the most recent version of either “software” or “%compiler” (or the “preferred” compiler version for this “software”, respectively).

Software modules via SPACK

LMod module files

If you want to have SPACK create “LMod readable” module files for your SPACK-built software, you need to configure a suitable module root directory in SPACK's <$HOME/path/to/environment>/spack.yml file:

  modules:
    default:
      roots:
        lmod: ~/myspackmodules

Links & References