Provide Token Relay capability

[jgrandja]

Spring Cloud Security provides the capability to relay OAuth 2.0 access tokens from the Edge Service (Zuul proxy) to downstream Resource Server(s).

We should implement the same feature as Token Relay is a common pattern required by an Edge (Proxy) Service.

[jgrandja]

Related #4921

[alwaysastudent]

Is this coming ? At minimum we should be able to

• Token relay using RestTemplate (+ Hystrix)
• Token relay while using FeignClient (+ Hystrix)

[jgrandja]

@alwaysastudent This won't make it into the 5.2 release. Also, we don't have plans on directly supporting RestTemplate and we haven't had discussions on providing support for FeignClient either. The current support is with WebClient.

You can easily implement Token Relay using any HTTP client of your choosing. All you need is the Jwt, which you can easily resolve JwtAuthenticationToken in a @Controller handler method and than obtain the Jwt using jwtAuthentication. getToken(). At this point you have the Jwt and can relay jwt.getTokenValue() to a downstream call.

Here's a Token Relay example using WebClient.

[jgrandja]

This is resolved via #7284 with the new ServerBearerExchangeFilterFunction in 5.2.0.