Merge pull request #522 from patricklucas/fix_instance_not_found_race

builder/amzon: fix race condition after launching EC2 instance

builder/amazon/common/state.go

@@ -62,11 +62,16 @@ func InstanceStateRefreshFunc(conn *ec2.EC2, i *ec2.Instance) StateRefreshFunc {
 	return func() (interface{}, string, error) {
 		resp, err := conn.Instances([]string{i.InstanceId}, ec2.NewFilter())
 		if err != nil {
-			log.Printf("Error on InstanceStateRefresh: %s", err)
-			return nil, "", err
+			if ec2err, ok := err.(*ec2.Error); ok && ec2err.Code == "InvalidInstanceID.NotFound" {
+				// Set this to nil as if we didn't find anything.
+				resp = nil
+			} else {
+				log.Printf("Error on InstanceStateRefresh: %s", err)
+				return nil, "", err
+			}
 		}
 
-		if len(resp.Reservations) == 0 || len(resp.Reservations[0].Instances) == 0 {
+		if resp == nil || len(resp.Reservations) == 0 || len(resp.Reservations[0].Instances) == 0 {
 			// Sometimes AWS just has consistency issues and doesn't see
 			// our instance yet. Return an empty state.
 			return nil, "", nil