On Sun, 2021-01-31 at 22:49 +0300, Oleg Pykhalov wrote:
> [...]
> First of all I want to ask did you try to override Shepherd yourself?

Yes, and I can confirm I could use #:supplementary-groups in
service definitions.  I override Shepherd with the mechanism in [1],
not with module-set!, however.

> It would be helpful to have a paragraph in the documentation how to
> override the Shepherd, and if you know a proper way, please add a small
> example of operating-system definition with overriden Shepherd and a
> basic service like OpenSSH.

Yes, would be very helpful, especially as it's easy to get wrong.
I'm currently occupied with other things, though.  As for an example:
your system configuration might do (as adjusted per previous e-mails),
with the following block ...

 (essential-services
  (modify-services
   (operating-system-default-essential-services this-operating-system)
   (shepherd-root-service-type 
config => (shepherd-configuration
                                          (inherit config)
                                          (shep
herd shepherd)))))
replaced by ...

 (essential-services
  (modify-services
   (operating-system-default-essential-services this-operating-system)
   (shepherd-root-service-type 
config => (shepherd-configuration
                                          (inherit config)
                                          (shep
herd shepherd-patched)))))

(otherwise no change in Shepherd is made), where shepherd-patched should
be defined somewhere in the beginning of the configuration file.
You could use your own shepherd-patched, or my shepherd-latest (attached):

[1] https://issues.guix.gnu.org/46043