Error with a JWT Token Reactive Authentication - spring

Question

I am learning about reactive programming and spring-webflux and I am trying to implement a JWT Token Authorization, but I get a runtime error about the ResponseEntity:
open class JwtReactiveAuthenticationManager(
private val userDetailsService: ReactiveUserDetailsService,
private val passwordEncoder: PasswordEncoder
): ReactiveAuthenticationManager {
private val log: Logger = LoggerFactory.getLogger(this.javaClass)
override fun authenticate(authentication: Authentication): Mono<Authentication> {
return if (authentication.isAuthenticated) {
Mono.just(authentication)
} else Mono.just(authentication)
.switchIfEmpty(Mono.error(BadCredentialsException("Invalid Credentials")))
.cast(UsernamePasswordAuthenticationToken::class.java)
.flatMap { authenticationToken: UsernamePasswordAuthenticationToken -> authenticateToken(authenticationToken) }
.publishOn(Schedulers.parallel())
.onErrorResume { Mono.error(BadCredentialsException("Invalid Credentials")) }
.filter { u: UserDetails -> passwordEncoder.matches(authentication.credentials as String, u.password) }
.switchIfEmpty(Mono.error(BadCredentialsException("Invalid Credentials")))
.map { u: UserDetails -> UsernamePasswordAuthenticationToken(authentication.principal, authentication.credentials, u.authorities) }
}
private fun authenticateToken(authenticationToken: UsernamePasswordAuthenticationToken): Mono<UserDetails>? {
val username = authenticationToken.name
log.info("checking authentication for user $username")
if (username != null && SecurityContextHolder.getContext().authentication == null) {
log.info("authenticated user $username, setting security context")
return this.userDetailsService.findByUsername(username)
}
return null
}
}
Controller method invoked:
#GetMapping("")
override fun list(): Flux<ResponseEntity<Exercise>> {
return repo.findAll().map { o -> ResponseEntity(o, HttpStatus.OK) }
}
2020-01-09 17:54:15.790 ERROR 14680 --- [oundedElastic-1] a.w.r.e.AbstractErrorWebExceptionHandler : [e22e00ce] 500 Server Error for HTTP GET "/api/exercises"
java.lang.IllegalArgumentException: Only a single ResponseEntity supported
at org.springframework.util.Assert.isTrue(Assert.java:118) ~[spring-core-5.2.2.RELEASE.jar:5.2.2.RELEASE]
Suppressed: reactor.core.publisher.FluxOnAssembly$OnAssemblyException:
Error has been observed at the following site(s):
|_ checkpoint ? org.springframework.security.web.server.authentication.AuthenticationWebFilter [DefaultWebFilterChain]
|_ checkpoint ? org.springframework.security.web.server.authorization.AuthorizationWebFilter [DefaultWebFilterChain]
|_ checkpoint ? org.springframework.security.web.server.authentication.AuthenticationWebFilter [DefaultWebFilterChain]
|_ checkpoint ? org.springframework.security.web.server.authorization.ExceptionTranslationWebFilter [DefaultWebFilterChain]
|_ checkpoint ? org.springframework.security.web.server.savedrequest.ServerRequestCacheWebFilter [DefaultWebFilterChain]
|_ checkpoint ? org.springframework.security.web.server.context.SecurityContextServerWebExchangeWebFilter [DefaultWebFilterChain]
|_ checkpoint ? org.springframework.security.web.server.context.ReactorContextWebFilter [DefaultWebFilterChain]
|_ checkpoint ? org.springframework.security.web.server.header.HttpHeaderWriterWebFilter [DefaultWebFilterChain]
|_ checkpoint ? org.springframework.security.config.web.server.ServerHttpSecurity$ServerWebExchangeReactorContextWebFilter [DefaultWebFilterChain]
|_ checkpoint ? org.springframework.security.web.server.WebFilterChainProxy [DefaultWebFilterChain]
|_ checkpoint ? org.springframework.boot.actuate.metrics.web.reactive.server.MetricsWebFilter [DefaultWebFilterChain]
|_ checkpoint ? HTTP GET "/api/exercises" [ExceptionHandlingWebHandler]
Stack trace:
at org.springframework.util.Assert.isTrue(Assert.java:118) ~[spring-core-5.2.2.RELEASE.jar:5.2.2.RELEASE]
at org.springframework.web.reactive.result.method.annotation.ResponseEntityResultHandler.handleResult(ResponseEntityResultHandler.java:121) ~[spring-webflux-5.2.2.RELEASE.jar:5.2.2.RELEASE]
at org.springframework.web.reactive.DispatcherHandler.handleResult(DispatcherHandler.java:169) ~[spring-webflux-5.2.2.RELEASE.jar:5.2.2.RELEASE]
at org.springframework.web.reactive.DispatcherHandler.lambda$handle$2(DispatcherHandler.java:147) ~[spring-webflux-5.2.2.RELEASE.jar:5.2.2.RELEASE]
at org.springframework.web.reactive.DispatcherHandler$$Lambda$1353.000000001B373A70.apply(Unknown Source) ~[na:na]
at reactor.core.publisher.MonoFlatMap$FlatMapMain.onNext(MonoFlatMap.java:118) ~[reactor-core-3.3.1.RELEASE.jar:3.3.1.RELEASE]
at reactor.core.publisher.Operators$MonoSubscriber.complete(Operators.java:1630) ~[reactor-core-3.3.1.RELEASE.jar:3.3.1.RELEASE]
at reactor.core.publisher.MonoFlatMap$FlatMapInner.onNext(MonoFlatMap.java:241) ~[reactor-core-3.3.1.RELEASE.jar:3.3.1.RELEASE]

Answer 1

you can't return Flux<ResponseEntity<Exercise>> as in multiple response entities.
change it to:
#GetMapping("")
override fun list(): Flux<Exercise> {
return repo.findAll()
}
if you wish to stream the data to the calling client, and it will probably go a lot better.