Comment 0 for bug 1925707

After installing Microstack multi-node using the instructions found here: https://ubuntu.com/openstack/install#multi-node-deployment
on Ubuntu 20.04.2 LTS it was unable to migrate instances between nodes. No error appeared in the GUI and logs showed the following error on the sending node:
openstack2 libvirtd[820]: operation failed: Failed to connect to remote libvirt URI qemu+tcp://openstack1/system: unable to connect to server at 'openstack1:16509': Connection refused
Verified that the ports were not open, though the conf looked correct in /var/snap/microstack/common/libvirt/libvirtd.conf. FOund that the conf file is no longer a valid way to enable listening / port for libvirtd: https://libvirt.org/manpages/libvirtd.html

Resolution is to copy the following files to /etc/systemd/system/:
/snap/microstack/222/usr/lib/systemd/system/libvirtd-tcp.socket
/snap/microstack/222/usr/lib/systemd/system/libvirtd.socket

edit the libvirtd.service lines, and then enable the socket / reload the systemctl daemon. Once thats done migrating instances could be done via GUI or CLI successfully.