Got two nodes with a failover ip.
The A record machine.domain.com points to that failover ip.
I have generated a letsencrypt-auto -d machine.domain.com certificate on the master node.
On the master node all is working well.
On the slave node I have SSL Library Error: error:0B080074:x509 certificate routines:X509_check_private_key:key values mismatch and apache doesn’t start.
keys and apache confs reside on a drbd volume shared between the two nodes.
If I disable ssl apache starts without problems.