Keycloak issuer validation and multi-tenancy approach

Question

Let's say we have several micro-services. Each of them uses Keycloak authentication. We have also load balancer based on for ex. nginx which has external URLs and different routes to keycloak (for ex. in OpenShift it can be https://keycloak.rhel-cdk.10.1.2.2.xip.io). But internally this address can be inaccessible. Also having micro-service configuration dependent on the load balancer URL is a bit weird. What what be more appropriate is to use internal keycloak auth URL inside of the micro-services or even short URI. But in this case token will not be validated because of issuer validation problem. How to configure this in good and flexible manner? Can I simply override realmInfoUrl in order to change the validation? Can I define what issuer will be used for client based token.

Another problem is how to better handle multi-tenant scenario? First on the client side I guess we don't have any specific support for multi-tenancy. I should handle this manually by switching between different URLs/headers and use proper Config Resolver. On the server side I need to dynamically provide a proper KeycloakDeployment instance for each case. Any other recommendations?

Answer 1

Unfortunately Keycloak is too restrictive with its token validation according to the issuer ("iss") field in the token. It requires that the URL used to validate the token matches the URL in the "iss" field.

A while ago I have opened a JIRA ticket for that problem (vote for it!): https://issues.jboss.org/browse/KEYCLOAK-5045