Open Stack

Hello,

I can ot find a real answer in the OpenStack-Ansible docs.
Can I add Ubuntu 18.04 compute nodes to my actueal all Ubuntu 16.04 cluster ?

Ubuntu 18.04 needs Rocky, so I will first migrate from Queens to Rocky.
But then, do I need to stick to 16.04 and plan an overall upgrade after ?

Of course, I understand that mixing Ubuntu release, will also mix kernel and 
qemu versions and can pose problems, for migrations for example.