user accounting and authorizing service(UAA)
Using JWT authentication without manually forwarding JWTs from request to internal request forces microservices to call other microservices over the gateway, which involves additional internal requests per one master requests. But even with forwarding, it’s not possible to cleanly separate user and machine authentication.
JWT (JSON Web Token)
JWT (JSON Web Token) is an industry standard, easy-to-use method for securing applications in a microservices architecture.
Tokens are generated by the gateway, and sent to the underlying microservices: as they share a common secret key, microservices are able to validate the token, and authenticate users using that token.
Those tokens are self-sufficient: they have both authentication and authorization information, so microservices do not need to query a database or an external system. This is important in order to ensure a scalable architecture