com.twitter.server.handler.ServerRegistryHandler.scala Maven / Gradle / Ivy

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package com.twitter.server.handler

import com.twitter.finagle.Service
import com.twitter.finagle.http.{Request, Response}
import com.twitter.finagle.server.ServerRegistry
import com.twitter.finagle.util.StackRegistry
import com.twitter.io.Buf
import com.twitter.server.util.HttpUtils.{new404, newResponse, parse}
import com.twitter.server.util.MetricSource
import com.twitter.server.view.StackRegistryView
import com.twitter.util.Future

private object ServerRegistryHandler {
  def render(servers: Seq[(String, StackRegistry.Entry)]): String =
    s"""
        
        
        
          ${
             (for {
                 (scope, entry) <- servers
               } yield {
                 s"""$scope"""
             }).mkString("\n")
           }
        
        
        
          ${
             (for ((scope, entry) <- servers) yield {
                val scopeDash = scope.replace("/", "-")
                s"""
                      
                        
                        
                          
                            Load:
                            ...

                            Failures:
                            ...

                            Success:
                            ...

                            Requests:
                            ...
                          
                        
                        
                        
                      

                    """
             }).mkString("\n")
           }
        """
}

/**
 * Renders information about servers registered to Finagle's ServerRegistry
 * in an html fragment. Servers can be queried by passing in the server name
 * as part of the uri (ex. "/admin/servers/myserver").
 */
class ServerRegistryHandler(
    uriPrefix: String,
    source: MetricSource = new MetricSource,
    registry: StackRegistry = ServerRegistry)
  extends Service[Request, Response] {
  // Search the metrics source for the stat scope that includes `serverName`.
  // The search namespace includes both "$serverName/" and "srv/$serverName"
  // to take into account finagle's ServerStatsReceiver. Note, unnamed servers are
  // ignored as we can't dissambiguate their stats.
  private[this] def findScope(serverName: String): Option[String] = {
    val k0 = s"$serverName"
    val k1 = s"srv/$serverName"
    if (source.contains(s"$k0/load")) Some(k0)
    else if (source.contains(s"$k1/load")) Some(k1)
    else None
  }

  def apply(req: Request): Future[Response] = {
    val (path, _) = parse(req.uri)
    path.stripPrefix(uriPrefix) match {
      case idx@("index.html" | "index.htm" | "index.txt" | "servers") =>
        val servers = (registry.registrants flatMap {
          case e: StackRegistry.Entry if e.name.nonEmpty =>
            for (scope <- findScope(e.name)) yield (scope, e)

          case _ => Nil
        }).toSeq
        val html = ServerRegistryHandler.render(servers)
        // This is useful to avoid the returned fragment being wrapped
        // with an index in the context of an ajax call.
        val typ = if (idx.endsWith(".txt")) "text/plain" else "text/html"
        newResponse(
          contentType = s"$typ;charset=UTF-8",
          content = Buf.Utf8(html)
        )

      case name =>
        val entries = registry.registrants filter { _.name == name }
        if (entries.isEmpty) new404(s"$name could not be found.") else {
          val server = entries.head
          val scope = findScope(server.name)
          val html = StackRegistryView.render(server, scope)
          newResponse(
            contentType = "text/html;charset=UTF-8",
            content = Buf.Utf8(html)
          )
        }
    }
  }

}