Butler stream servers can generate client address.

logdog/client/cmd/logdog_butler/subcommand_serve.go

 // Copyright 2015 The LUCI Authors. All rights reserved.
 // Use of this source code is governed under the Apache License, Version 2.0
 // that can be found in the LICENSE file.
 
 package main
 
 import (
         log "github.com/luci/luci-go/common/logging"
         "github.com/luci/luci-go/logdog/client/butler"
 
@@ skipping 22 matching lines @@
 func (cmd *serveCommandRun) Run(app subcommands.Application, args []string, _ subcommands.Env) int {
         a := app.(*application)
 
         if err := cmd.uri.Validate(); err != nil {
                 log.Fields{
                         "flag":  "-streamserver_uri",
                         "value": cmd.uri,
                 }.Errorf(a, "Invalid stream server URI.")
                 return configErrorReturnCode
         }
-        streamServer := createStreamServer(a, cmd.uri)
+        streamServer, err := createStreamServer(a, cmd.uri)
+        if err != nil {
+                log.WithError(err).Errorf(a, "Failed to create stream server.")
+                return runtimeErrorReturnCode
+        }
 
         if err := streamServer.Listen(); err != nil {
                 log.Errorf(log.SetError(a, err), "Failed to connect to stream server.")
                 return runtimeErrorReturnCode
         }
 
         // We think everything will work. Configure our Output instance.
         of, err := a.getOutputFactory()
         if err != nil {
                 log.WithError(err).Errorf(a, "Failed to get output factory instance.")
@@ skipping 10 matching lines @@
                 b.AddStreamServer(streamServer)
                 return b.Wait()
         })
         if err != nil {
                 logAnnotatedErr(a, err, "Failed to serve.")
                 return runtimeErrorReturnCode
         }
 
         return 0
 }