如何使用 http4s 服务器和客户端库作为代理？

Question

我想使用http4s作为代理（如nginx），如何将所有数据从我的http4s服务器转发到另一个http服务器？

我真正想要做的是在执行转发功能之前在每个请求上附加一个验证功能。希望像这样：

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？
谢谢

已更新

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 服务器监听 28080）：
但发生错误：

[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...")
      }

  }

它对我的 REST API 网络服务器来说已经足够好了。
代理 scala-lang.org 测试时出现一些错误：

[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，您绝对应该避免在代码中调用 unsafeRunSync。您通常应该在您的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？

How to use http4s server and client library as a proxy?

scala

http4s

已更新

最新版本