How do I access diamond packages?

When using Guix, all available packages come from the default guix channel: GNU Guix. However, it is possible to add channels to extend the list of available packages. As part of the DIAMOND project, some code has been packaged using Guix and are available in the guix-packages channel. To add this specific channel and thus be able to install the packages using the guix install command, you need to create a ~/.config/guix/channels.scm file on your machine or on the HPC infrastructure you will be using. This file needs to contain the following lines:

;; Add gricad packages to those Guix provides.
(cons (channel
        (name 'guix-packages)
        (branch "public-packages")
        (url "https://gricad-gitlab.univ-grenoble-alpes.fr/diamond/guix-packages.git"))
      %default-channels)

Once this is done, the guix pull command will update the package collection from the standard channel (GNU Guix) and the Diamond channel (guix-packages).

Caution

Once guix pull is complete, it is important to run the following commands to ensure that you are using the latest guix command:

GUIX_PROFILE="$HOME/.config/guix/current"
. "$GUIX_PROFILE/etc/profile"

Finally, to check that you have access to the Diamond packages, you can try searching for the quantum-espresso package:

guix search quantum-espresso

How do I use Guix packages?

The guix shell command

This command creates a temporary software environment containing the dependencies that allow the code to be used as desired. In general, we recommend the use of the --pure flag and a manifest.scm file. The former plays a similar role to the --cleanenv flag in Apptainer and is used to clean up the environment variables on the host system before the temporary software environment appears. The manifest.scm file lists all the packages required for the code to run correctly. Several examples of manifests are available in the gitlab repository, which contains all the Guix packages defined as part of the Diamond project: guix-packages.

A classic use of the guix shell command can therefore be summarised in the following line

guix shell --pure -m lammps_mpi_manifest.scm

The guix time-machine command

Some packages require a specific version of one or more dependencies. However, if you have run the guix pull command, then you have the latest versions of all packages. So you may find yourself in a situation where the code you want to use won’t build. Don’t panic, Guix has a ready-made solution for these problems! The guix time-machine command allows you to revert to a previous commit, and thus access earlier versions of dependencies. In practice, it is recommended to use a channels.scm file containing information about the desired commit. Again, several examples of channel files are available in the Diamond project’s Gitlab repository: guix-packages.

A typical use of the `guix time-machine’ command can therefore be summarised in the following line

guix time-machine --channels=quantum-espresso_channels.scm \
    -- shell --pure -m quantum-espresso_manifest.scm