From d7655a9db0d083ca5d7db56cdbbbef0716e1a91b Mon Sep 17 00:00:00 2001
From: Jeff Mitchell <jeffrey.mitchell@gmail.com>
Date: Mon, 15 Oct 2018 11:02:53 -0400
Subject: [PATCH] Buffer authhandler output channel to prevent hang on shutdown
 (#5507)

Fixes #5026
---
 command/agent/auth/auth.go | 6 ++++--
 1 file changed, 4 insertions(+), 2 deletions(-)

diff --git a/command/agent/auth/auth.go b/command/agent/auth/auth.go
index 6a9127f9b4..f3733a4ecc 100644
--- a/command/agent/auth/auth.go
+++ b/command/agent/auth/auth.go
@@ -43,8 +43,10 @@ type AuthHandlerConfig struct {
 
 func NewAuthHandler(conf *AuthHandlerConfig) *AuthHandler {
 	ah := &AuthHandler{
-		DoneCh:   make(chan struct{}),
-		OutputCh: make(chan string),
+		DoneCh: make(chan struct{}),
+		// This is buffered so that if we try to output after the sink server
+		// has been shut down, during agent shutdown, we won't block
+		OutputCh: make(chan string, 1),
 		logger:   conf.Logger,
 		client:   conf.Client,
 		random:   rand.New(rand.NewSource(int64(time.Now().Nanosecond()))),