keycloak - realm resolution based on username (ema

问题:

I'm working on a multi tenant project where usernames are actually their email addresses and the domain of the email serves as a tenant identifier.

Now in keycloak I'll have different realms per tenant, but I want to have a single login page for all tenants and the actual realm that will do the authentication to be somehow resolved by the username (email address).

How do I go about doing that?

I found a thread on the mailing list (that I cant find now...) that discussed the same problem. It was something along the lines of - create a main realm that will "proxy" to the others, but I'm not quite sure how to do that.