resources: aws: ec2: Close closeChan before server shutdown

This patch makes sure that closeChan is closed as soon as the main loop
returns, so any channel operations are unblocked before we run shutdown.
This ensures that the server's goroutine can return before shutdown
completes and we don't panic by trying to serve the client after
shutdown returns.

resources/aws_ec2.go

@@ -632,7 +632,6 @@ func (obj *AwsEc2Res) snsWatch() error {
 	send := false
 	var exit *error
 	defer obj.wg.Wait()
-	defer close(obj.closeChan)
 	// create the sns listener
 	// closing is handled by http.Server.Shutdown in the defer func below
 	listener, err := obj.snsListener(obj.WatchListenAddr)
@@ -655,6 +654,7 @@ func (obj *AwsEc2Res) snsWatch() error {
 			log.Printf("%s: sns server shutdown cancelled", obj)
 		}
 	}()
+	defer close(obj.closeChan)
 	obj.wg.Add(1)
 	// start the sns server
 	go func() {