If you been banging your head against a wall for an hour or so, trying to figure out what is causing error

Joining server certificate SAN does not contain join token name

when trying to add a node to a microceph cluster, bang no more, I’ve found a reason and I will share it with you.

The thing is, when you first generate a cluster join token with

sudo microceph cluster add <host-name>

and then try to add a node to the cluster with

sudo microceph cluster join <token>

It will only work on a host with a name you generated the token for! Hostnames have to match or you will get the “Joining server certificate SAN does not contain join token name“.

How to fix it? Simple, when you add a node with a hostname host7, generate token especially for this host with:

sudo microceph cluster add host7