Mysql – thesql setting up encryption (ssl) without client certificats

It looks like you've run into a known bug. Check out documentation on it at the mysql bug tracker

It depends how you use client certs to authenticate and authorise users. Do you allow anyone with a cert signed by someone you recognise or must it be signed and the CN equal something specific or equal a user in a group? Does your current web server handle authorisation or does your app?

The typical way to do this would be to terminate the SSL connection on a loadbalancer. This load balancer would be the "full-blown HTTPS site" and would need to be configured to request a client certificate. Your loadbalancer would then perform a check to see if the cert was signed by a trusted CA. The loadbalancer would then add details from the SSL cert, such as the DN, as HTTP Headers to plain HTTP request to your app. Your app would then check these HTTP headers and authorise the user based on a trust between the app and the loadbalancer. I've seen the accomplished with all major loadbalancers such as F5, ZXTM and even Apache HTTP Server.