Spring cloud oauth 2 with ingress kubernetes

I have not used Spring Cloud OAuth 2 but as OAuth is a standard I believe you can set it up if you are using Nginx Ingress as the ingress controller, you can specify and external Oauth Provider (As OAuth generally has the same flow) like this on your ingress:

...metadata:  name: application  annotations:    nginx.ingress.kubernetes.io/auth-url: "https://$host/oauth2/auth"    nginx.ingress.kubernetes.io/auth-signin: "https://$host/oauth2/start?rd=$escaped_request_uri"...

You can find more information here with an example of using GitHub as an OAuth provider

There are currently three different nginx-ingress-controllers (see here), which differ in functionality. I believe that none of these ingress controllers themselves can perform an oauth token introspection. However, requests can be routed to the authorization server's introspection interface using the auth_request module.

Specifically for your case, you can use the auth-url annotation (see) in the ingress controller to direct the requests to the introspection interface of the spring cloud oauth2 server (see). The introspection interface is available under /oaut/check_token by default when @EnableAuthorizationServer is used. If the introspection interface returns a 2XX, the ingress will forward the request. This functionality is based on the auth_request module, which expects a 2xx response code from the external service if the access is allowed and 401 or 403 if denied.

If you use JWTs and want to validate the request by only checking the signature, this can in some cases actually be done by the ingress itself. To my knowledge, only the nginx plus ingress controller (paid) can validate JWTs. But there is also the nginx-based kong-ingress controller, which you can equip with pulgins (see here). There is e.g. promoted with oauth2 integration and JWT validation.

Did you find out more than me?