From e530eea2265848bc2bf88c7cce4371ebed5f3ee8 Mon Sep 17 00:00:00 2001
From: Ryan Uber <ru@ryanuber.com>
Date: Fri, 22 Aug 2014 18:11:06 -0700
Subject: [PATCH] provider/aws: fix panic when user_data receives nil from
 StateFunc

---
 builtin/providers/aws/resource_aws_instance.go | 9 +++++++--
 1 file changed, 7 insertions(+), 2 deletions(-)

diff --git a/builtin/providers/aws/resource_aws_instance.go b/builtin/providers/aws/resource_aws_instance.go
index d911ad975..3427d44cd 100644
--- a/builtin/providers/aws/resource_aws_instance.go
+++ b/builtin/providers/aws/resource_aws_instance.go
@@ -88,8 +88,13 @@ func resourceAwsInstance() *schema.Resource {
 				Optional: true,
 				ForceNew: true,
 				StateFunc: func(v interface{}) string {
-					hash := sha1.Sum([]byte(v.(string)))
-					return hex.EncodeToString(hash[:])
+					switch v.(type) {
+					case string:
+						hash := sha1.Sum([]byte(v.(string)))
+						return hex.EncodeToString(hash[:])
+					default:
+						return ""
+					}
 				},
 			},