SSL configuration of Apache2 with Traefik as reverse proxy?

I do not understand how, or at all, configure Apache SSL when Traefik is used as a reverse proxy.

In the past, I used dehydrated on the Apache machine itself. I have configured SSLCertificateFile etc. in Apache and everything worked.

But I do not understand at all how to configure Apache, when it is behind traefik in a different container. What should I configure about Apache?

Traefik and Apache are located in different LXC containers. Does Traefik support all certificates in its own container or do I have to bind it to Apache? Who is supposed to deal with encryption – apache or traefik?