Add webserver "apache" user to other groups

Are you kidding

the problem comes from the ACL...see :

# getfacl /var/lib/nethserver/ibay/tutu/

getfacl: Removing leading '/' from absolute path names
# file: var/lib/nethserver/ibay/tutu/
# owner: admin
# group: plume
# flags: -s-
user::rwx
user:apache:rwx
user:toto:rwx
group::r-x
group:yuyu:rwx
group:plume:rwx
mask::rwx
other::---
default:user::rwx
default:user:apache:rwx
default:user:toto:rwx
default:group::r-x
default:group:yuyu:rwx
default:group:plume:rwx
default:mask::rwx
default:other::---

apache cannot write following the ACL restrictions

try

setfacl -P -R -m u:apache:rwX,d:u:apache:rwX /var/lib/nethserver/ibay/tutu/

and you will be able to write in the whole Ibay....but each time you will reset the permission in the Ibay Panel, or reconfigure the Ibay with the event ibay-modify, you will reset the acl