uncomment this line in file /etc/libvirt/libvirt.conf
uri_default = "qemu:///system"
was enough for me in fedora 29 .
Edit: as it says here https://libvirt.org/uri.html for non root users that file also needs to be in $XDG_CONFIG_HOME/libvirt/libvirt.conf
which in my case is:
so i copy the file there (on my fresh ...
You can probably do this by using sudo to allow users (one/some/all) to run the script as a user that is a member of the group, etc. that has access rights to the directory.
This page - https://lifecs.likai.org/2016/02/generic-setuidsetgid-wrapper-for-scripts.html seems to tackle your problem quite well, the sudoers line suggested -
ALL ALL = (script-...