SPack is a package manager that provides a “modules” interface, able to handle multiple versions, dependencies, and build environments. It can be used together with, or as a replacement for, the old modules environment that has been used for a long time.

To use the latest SPack repository on Minerva (there are some older /home/SPACK* left), you must source a config file:

. /home/SPACK2021/share/spack/setup-env.sh

After that, you may use spack help. Most important commands I use:

• spack list hdf5 to find (source) packages matching hdf5
• spack info hdf5 to show the description of the hdf5 (source) package
• spack find hdf5 to check whether the package has already been built and installed (as binary and module)
• spack find -lv hdf5 provides more details:
  • green: compiler version
  • cyan: package version
  • pale blue: variants user to build (~ prefixes disabled, + enabled variants)
  • gray: package hash
• spack find … -d hdf5 lists the (build) dependencies

You will have to make yourself familiar with the special characters used:

• + enables a variant, ~ disables it
• ^ specifies a build include
• % denotes a compiler, @ a version
• / can be used to select hashes

To load the o2x4itb hdf5@1.8.19~cxx~debug~fortran~hl+mpi+pic+shared~szip~threadsafe built with %gcc@7.3.0 you saw listed with the last find command, you may choose from the following options:

• module load hdf5-1.8.19-gcc-7.3.0-o2x4itb (old style, module name combines from ${packagename}-${packageversion}-${compiler}-${compilerversion}-${hash}) or
• spack load hdf5 ~cxx +mpi works (at the time of this writing)
• spack load hdf5 /o2x4 (with the hash further shortened) will also get the right one. This even works without a package name!
• spack load hdf5 %gcc@7.3.0 +mpi will match (and load, although the docs suggest that an error would result!) multiple modules! Don't forget to module (purge|unload)!

In general, spack load is slow, and prone to ambiguity errors. Use module list -t to identify such situations, and get the names of loaded modules one-per-line. Package dependencies are now resolved automatically (even if not invoked with -r).

IMPORTANT: The /home/SPACK2021/ tree is read-only (and there are no means yet to make it collaborative). Therefore spack install will not work for you! If you need a package that hasn't been installed yet, ask me (Steffen), if possible keep the right options (variants, includes) at hand!

(To be extended.)