memcached unix socket: fix panic. Do not recreate conn inside if

closes #841

CHANGELOG.md

@@ -19,6 +19,7 @@
 - [#898](https://github.com/influxdata/telegraf/issues/898): Put database name in quotes, fixes special characters in the database name.
 - [#656](https://github.com/influxdata/telegraf/issues/656): No longer run `lsof` on linux to get netstat data, fixes permissions issue.
 - [#907](https://github.com/influxdata/telegraf/issues/907): Fix prometheus invalid label/measurement name key.
+- [#841](https://github.com/influxdata/telegraf/issues/841): Fix memcached unix socket panic.
 
 ## v0.11.1 [2016-03-17]
 

plugins/inputs/memcached/memcached.go

@@ -94,14 +94,15 @@ func (m *Memcached) gatherServer(
 	acc telegraf.Accumulator,
 ) error {
 	var conn net.Conn
+	var err error
 	if unix {
-		conn, err := net.DialTimeout("unix", address, defaultTimeout)
+		conn, err = net.DialTimeout("unix", address, defaultTimeout)
 		if err != nil {
 			return err
 		}
 		defer conn.Close()
 	} else {
-		_, _, err := net.SplitHostPort(address)
+		_, _, err = net.SplitHostPort(address)
 		if err != nil {
 			address = address + ":11211"
 		}
@@ -113,6 +114,10 @@ func (m *Memcached) gatherServer(
 		defer conn.Close()
 	}
 
+	if conn == nil {
+		return fmt.Errorf("Failed to create net connection")
+	}
+
 	// Extend connection
 	conn.SetDeadline(time.Now().Add(defaultTimeout))