Call Authenticator Microservice From ApiGateway ServerSecurityContextRepository - spring-boot

Question

Introduction
I have a microservice responsible for authenticating each API call to my server. so when any request comes API gateway is supposed to call the authenticator for the validation with token and after this is a success the actual API call process to the intended destination.
API Gateway is a spring-cloud-starter-gateway project using spring-boot-starter-webflux. And the other microservice can be connected using FeignClient.
Problem
I am trying to call the feignclient method from the ReactiveAuthenticationManager authenticate(). and I need some kind of possibility to intercept it and validate this to either throw error or return a success mono.
But as of now the flatmap is not being called.
Code
import com.atlpay.pgapigateway.JwtAuthenticationToken
import org.springframework.beans.factory.annotation.Autowired
import org.springframework.security.core.Authentication
import org.springframework.security.core.context.SecurityContext
import org.springframework.security.core.context.SecurityContextImpl
import org.springframework.security.web.server.context.ServerSecurityContextRepository
import org.springframework.stereotype.Component
import org.springframework.web.server.ServerWebExchange
import reactor.core.publisher.Mono
#Component
class SecurityContextRepository : ServerSecurityContextRepository {
#Autowired
private lateinit var authenticationManager: AuthenticationManager
override fun save(swe: ServerWebExchange, sc: SecurityContext): Mono<Void> {
return Mono.empty()
}
override fun load(serverWebExchange: ServerWebExchange): Mono<SecurityContext> {
val path = serverWebExchange.request.path
//send request to authentication manager
val auth: Authentication = JwtAuthenticationToken(
"",
serverWebExchange.request.method!!.name,
path.toString(),
serverWebExchange.request.headers
)
return this.authenticationManager.authenticate(auth)
.map { authentication ->
SecurityContextImpl(authentication)
}
}
}
The above SecurityContextRepository calls the AuthenticationManager mentioned below.
import com.atlpay.pgapigateway.JwtAuthenticationToken
import com.atlpay.pgjavacontracts.feign.TestFeign
import org.springframework.beans.factory.annotation.Autowired
import org.springframework.security.authentication.ReactiveAuthenticationManager
import org.springframework.security.core.Authentication
import org.springframework.stereotype.Component
import reactor.core.publisher.Mono
#Component
class AuthenticationManager : ReactiveAuthenticationManager {
#Autowired
private lateinit var testFeign: TestFeign
override fun authenticate(authentication: Authentication): Mono<Authentication> {
val authToken = (authentication as JwtAuthenticationToken).token
val toReturnUserNamePasswordAuthenticationToken = JwtAuthenticationToken(
authentication.token,
authentication.httpMethod,
authentication.path,
authentication.httpHeaders
)
return testFeign.getUsers()
.flatMap { response ->
//if error throw error
>>>>>> println("This is just a test >> ${response.status()}")
Mono.just(toReturnUserNamePasswordAuthenticationToken as Authentication)
}
.then(Mono.just(toReturnUserNamePasswordAuthenticationToken as Authentication))
}
}
From the above class I am expecting to intercept the call the validate the response code of the feignclient. at this line -
println("This is just a test >> ${response.status()}")
But this is never called!!
FeignClient is just a mock api for testing -
import feign.Response
import org.springframework.web.bind.annotation.PostMapping
import reactivefeign.spring.config.ReactiveFeignClient
import reactor.core.publisher.Mono
#ReactiveFeignClient(url = "https://630369f20de3cd918b34e39e.mockapi.io", name = "testFeign")
interface TestFeign {
#PostMapping("/users")
fun getUsers(): Mono<Response>
}
Attempts
Tried to make a call using Restclient blocking api. and got the result.
but I want it to be load balanced so changed to a LoadBalanced rest client and used the URL 'http://myMicroServiceName/validate' this gives me a block()/blockfirst()/blocklast() are blocking error.
So this is out of scope for now.
I think I am missing some basic structure in the Reactive part or its an issue with the Apigateway ReactiveAuthenticationManager.
Update
Found an solution with webfilter. will update with an answer soon.
Any suggestion is appreciated.