From c419b5031df1ecdcf749f3f0c091a10c603358f1 Mon Sep 17 00:00:00 2001
From: dmathieu <42@dmathieu.com>
Date: Thu, 1 Feb 2018 16:13:05 +0100
Subject: [PATCH] log all the available interfaces when none were found

---
 main.go | 8 +++++++-
 1 file changed, 7 insertions(+), 1 deletion(-)

diff --git a/main.go b/main.go
index 856ccf2e7a..c336c3e5d9 100644
--- a/main.go
+++ b/main.go
@@ -474,7 +474,13 @@ func LookupExtIface(ifname string, ifregex string) (*backend.ExternalInterface,
 
 		// Check that nothing was matched
 		if iface == nil {
-			return nil, fmt.Errorf("Could not match pattern %s to any of the available network interfaces", ifregex)
+			var availableFaces []string
+			for _, f := range ifaces {
+				ip, _ := ip.GetIfaceIP4Addr(&f) // We can safely ignore errors. We just won't log any ip
+				availableFaces = append(availableFaces, fmt.Sprintf("%s:%s", f.Name, ip))
+			}
+
+			return nil, fmt.Errorf("Could not match pattern %s to any of the available network interfaces (%s)", ifregex, strings.Join(availableFaces, ", "))
 		}
 	} else {
 		log.Info("Determining IP address of default interface")