Question

我想使用http4s作为代理（如nginx），如何将我的http4s服务器中的所有数据转发到另一个http服务器？

我真正想做的是在执行转发功能之前在每个请求上附加验证功能。希望这样：

HttpService[IO] {
  case request =>
    val httpClient: Client[IO] = Http1Client[IO]().unsafeRunSync
    if(verifySuccess(request)) { // forward all http data to host2 and
                                 // get a http response.
      val result = httpClient.forward(request, "http://host2")
      result
    } else {
      Forbidden //403
    }
}

如何使用http4s及其客户端执行此操作？感谢

更新

在@TheInnerLight的帮助下，我尝试使用代码片段：

  val httpClient = Http1Client[IO]()

  val service: HttpService[IO] = HttpService[IO] {
    case req =>
      if(true) {
        for {
          client <- httpClient
          newAuthority = req.uri.authority.map(_.copy(host = RegName("scala-lang.org"), port = Some(80)))
          proxiedReq = req.withUri(req.uri.copy(authority = newAuthority))
          response <- client.fetch(proxiedReq)(IO.pure(_))
        } yield response
      } else {
        Forbidden("Some forbidden message...")
      }

  }

请求：http://localhost:28080（http4s服务器收听28080）：
但发生了一个错误：

[ERROR] org.http4s.client.PoolManager:102 - Error establishing client connection for key RequestKey(Scheme(http),localhost) 
java.net.ConnectException: Connection refused
    at sun.nio.ch.UnixAsynchronousSocketChannelImpl.checkConnect(Native Method)
    at sun.nio.ch.UnixAsynchronousSocketChannelImpl.finishConnect(UnixAsynchronousSocketChannelImpl.java:252)
    at sun.nio.ch.UnixAsynchronousSocketChannelImpl.finish(UnixAsynchronousSocketChannelImpl.java:198)
    at sun.nio.ch.UnixAsynchronousSocketChannelImpl.onEvent(UnixAsynchronousSocketChannelImpl.java:213)
    at sun.nio.ch.KQueuePort$EventHandlerTask.run(KQueuePort.java:301)
    at java.lang.Thread.run(Thread.java:748)
[ERROR] org.http4s.server.service-errors:88 - Error servicing request: GET / from 0:0:0:0:0:0:0:1 
java.net.ConnectException: Connection refused
    at sun.nio.ch.UnixAsynchronousSocketChannelImpl.checkConnect(Native Method)
    at sun.nio.ch.UnixAsynchronousSocketChannelImpl.finishConnect(UnixAsynchronousSocketChannelImpl.java:252)
    at sun.nio.ch.UnixAsynchronousSocketChannelImpl.finish(UnixAsynchronousSocketChannelImpl.java:198)
    at sun.nio.ch.UnixAsynchronousSocketChannelImpl.onEvent(UnixAsynchronousSocketChannelImpl.java:213)
    at sun.nio.ch.KQueuePort$EventHandlerTask.run(KQueuePort.java:301)
    at java.lang.Thread.run(Thread.java:748)

最新版本

 val httpClient: IO[Client[IO]] = Http1Client[IO]()

  override val service: HttpService[IO] = HttpService[IO] {
    case req =>
      val hostName = "scala-lang.org"
      val myPort = 80
      if(true) {
        val newHeaders = {
          val filterHeader = req.headers.filterNot{h =>
            h.name == CaseInsensitiveString("Connection") ||
            h.name == CaseInsensitiveString("Keep-Alive") ||
            h.name == CaseInsensitiveString("Proxy-Authenticate") ||
            h.name == CaseInsensitiveString("Proxy-Authorization") ||
            h.name == CaseInsensitiveString("TE") ||
            h.name == CaseInsensitiveString("Trailer") ||
            h.name == CaseInsensitiveString("Transfer-Encoding") ||
            h.name == CaseInsensitiveString("Upgrade")
          }
          filterHeader.put(Header("host", hostName))
        }

        for {
          client <- httpClient
          newAuthority = req.uri.authority
            .map(_.copy(host = RegName(hostName), port = Some(myPort)))
            .getOrElse( Authority(host = RegName(hostName), port = Some(myPort)))
          proxiedReq = req.withUri(req.uri.copy(authority = Some(newAuthority)))
            .withHeaders(newHeaders)
          response <- client.fetch(proxiedReq)(x => IO.pure(x))
        } yield {
          val rst = response
          rst
        }

      } else {
        Forbidden("Some forbidden message...")
      }

  }

它适用于我的REST API Web服务器代理scala-lang.org用于测试时出现错误：

[ERROR] org.http4s.blaze.pipeline.Stage:226 - Error writing body 
org.http4s.InvalidBodyException: Received premature EOF.

Answer 1

这样的事情怎么样：

HttpService[IO] {
  case req =>
    if(verifyRequest(req)) {
      for {
        client <- Http1Client[IO]()
        newHost = "host2"
        newAuthority = Authority(host = RegName("host2"), port = Some(80))
        proxiedReq =
          req.withUri(req.uri.copy(authority = Some(newAuthority)))
           .withHeaders(req.headers.put(Header("host", newHost)))
        response <- client.fetch(proxiedReq)(IO.pure(_))
      } yield response
    } else {
      Forbidden("Some forbidden message...")
    }
}

请注意，您应该通过调用unsafeRunSync来避免乱丢代码。您通常应该在程序中最多使用一次（在Main中）。在其他情况下，您应该专注于将效果提升到您正在使用的monad中。

如何使用http4s服务器和客户端库作为代理？

更新

最新版本

1 个答案: