Butler: Infer host from "coordinator-host" flag.

logdog/client/cmd/logdog_butler/main.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 (
         "bytes"
         "flag"
         "fmt"
@@ skipping 83 matching lines @@
                 a.outputConfig.AddFactory(f)
         }
 
         a.maxBufferAge = clockflag.Duration(butler.DefaultMaxBufferAge)
 
         fs.Var(&a.project, "project",
                 "The log prefix's project name (required).")
         fs.Var(&a.prefix, "prefix",
                 "Prefix to apply to all stream names.")
         fs.StringVar(&a.coordinatorHost, "coordinator-host", "",
-                "The Coordinator host to pass on to subprocesses.")
+                "The Coordinator service host to use.")
         fs.Var(&a.outputConfig, "output",
                 "The output name and configuration. Specify 'help' for more information.")
         fs.IntVar(&a.outputWorkers, "output-workers", butler.DefaultOutputWorkers,
                 "The maximum number of parallel output dispatches.")
         fs.Var(&a.globalTags, "tag",
                 "Specify key[=value] tags to be applied to all log streams. Individual treams may override. Can "+
                         "be specified multiple times.")
         fs.Var(&a.maxBufferAge, "output-max-buffer-age",
                 "Send buffered messages if they've been held for longer than this period.")
         fs.BoolVar(&a.noBufferLogs, "output-no-buffer", false,
@@ skipping 237 matching lines @@
 
         paniccatcher.Do(func() {
                 rc = mainImpl(ctx, chromeinfra.DefaultAuthOptions(), os.Args[1:])
         }, func(p *paniccatcher.Panic) {
                 log.Fields{
                         "panic.error": p.Reason,
                 }.Errorf(ctx, "Panic caught in main:\n%s", p.Stack)
                 rc = runtimeErrorReturnCode
         })
 }