如何在服务中访问 header？

Question

我正在尝试在后端的 gRPC 中处理 JWT-authentication。我可以在拦截器中提取 JWT，但如何在我的服务中访问它？我认为应该使用 CoroutineContextServerInterceptor 来完成，但这不起作用：

val jwtKey: Context.Key<String> = Context.key("jwtKey")

fun main() {
    ServerBuilder.forPort(8980).intercept(UserInjector).addService(MyService).build().start().awaitTermination()
}

object UserInjector : CoroutineContextServerInterceptor() {
    override fun coroutineContext(call: ServerCall<*, *>, headers: Metadata): CoroutineContext {
        val jwtString = headers.get(Metadata.Key.of("jwt", Metadata.ASCII_STRING_MARSHALLER))
        println("coroutineContext: $jwtString")
        return GrpcContextElement(Context.current().withValue(jwtKey, jwtString))
    }
}

object MyService : MyServiceGrpcKt.MyServiceCoroutineImplBase() {
    override suspend fun testingJWT(request: Test.MyRequest): Test.MyResponse {
        println("testingJWT: ${jwtKey.get()}")
        return Test.MyResponse.getDefaultInstance()
    }
}

输出：

coroutineContext: something
testingJWT: null

Answer 1

我认为您需要在它自己的协程上下文元素中传播它。

class JwtElement(val jwtString: String) : CoroutineContext.Element {
  companion object Key : CoroutineContext.Key<JwtElement>
  override val key: CoroutineContext.Key<JwtElement>
    get() = Key
}

object UserInjector : CoroutineContextServerInterceptor() {
  override fun coroutineContext(call: ServerCall<*, *>, headers: Metadata): CoroutineContext {
    val jwtString = headers.get(Metadata.Key.of("jwt", Metadata.ASCII_STRING_MARSHALLER))
    println("coroutineContext: $jwtString")
    return JwtElement(jwtString)
  }
}

object MyService : MyServiceGrpcKt.MyServiceCoroutineImplBase() {
  override suspend fun testingJWT(request: Test.MyRequest): Test.MyResponse {
    println("testingJWT: ${coroutineContext[JwtElement]}")
    return Test.MyResponse.getDefaultInstance()
  }
}

如何在服务中访问 header？

How can I access header in a service?

kotlin

grpc

kotlin-coroutines

grpc-kotlin