Are you exposing the necessary ports from these 700+ containers on the host in order to facilitate multi-host communication? How do you solve service discovery?

Are you exposing the necessary ports from these 700+ containers on the host in order to facilitate multi-host communication? How do you solve service discovery? For us the main reason to go with overlay networking is that it basically solves service discovery (in our specific case) over the entire cluster out of the box (by using Docker internal DNS). No need to change anything in the services themselves, they just need to connect to each other using DNS names.