Hi Ludo,

On Tue,  4 Jun 2019 23:01:14 +0200
Ludovic Courtès <ludo@gnu.org> wrote:

> +@defvr {Scheme Variable} singularity-service-type
> +This is the type of the service that runs
> +@url{https://www.sylabs.io/singularity/, Singularity}, 

Does it?
Doesn't it just "allow you to invoke"?

> +                  (substitute* (find-files "libexec/cli" "\\.exec$")
> +                    (("\\$SINGULARITY_libexecdir/singularity/bin/([a-z]+)-suid"
> +                      _ program)
> +                     (string-append "/run/setuid-programs/singularity-"
> +                                    program "-helper")))

Is absolute path OK?  There have been some efforts to get guix to relocate in
the past.  Does this apply here?

> +        ;; Create the directories that Singularity 2.6 expects to find.
> +        (for-each (lambda (directory)
> +                    (mkdir-p (string-append "/var/singularity/mnt/"
> +                                            directory)))
> +                  '("container" "final" "overlay" "session")))))

Are permissions OK?

LGTM!