Is federation from keycloak instance of latest version to another keycloak instance of older version

Hi,

We are mocroservice environment. We do use keycloak for id provider, authorize rest API from clients, authorize rest API from service to service calls as well. We do get token from angular application when user logs in. And pass the same token in rest call in header to get authenticated and authorized by keycloak. Use the same token to call other mocroservices if necessary.

We wanted to upgrade from kc 13 to kc 23. Achieved poc with one of our service and working. Now question is, as we can’t upgrade all the mocroservices in one sprint, we want to do one bye one. For this we need to have 2 instances of keycloak for each version. And then should be able to generate token from one instance to another depends on the version of keycloak. Is this possible?
If not, what suggestion would you give for a mocroservices environment if we can’t upgrade all at once