From ab4b1e1f0945419aeeef76911ef91eee92b22233 Mon Sep 17 00:00:00 2001
From: Diptanu Choudhury <diptanuc@gmail.com>
Date: Fri, 18 Mar 2016 21:44:22 -0700
Subject: [PATCH] Using the interface name to find bind address for network
 services

---
 command/agent/agent.go | 10 ++++++++--
 command/agent/util.go  | 21 +++++++++++++++++++--
 2 files changed, 27 insertions(+), 4 deletions(-)

diff --git a/command/agent/agent.go b/command/agent/agent.go
index 76b7771b6..a8088325e 100644
--- a/command/agent/agent.go
+++ b/command/agent/agent.go
@@ -71,7 +71,7 @@ func (a *Agent) serverConfig() (*nomad.Config, error) {
 	conf.LogOutput = a.logOutput
 	conf.DevMode = a.config.DevMode
 	conf.Build = fmt.Sprintf("%s%s", a.config.Version, a.config.VersionPrerelease)
-	if i.config.Region != "" {
+	if a.config.Region != "" {
 		conf.Region = a.config.Region
 	}
 	if a.config.Datacenter != "" {
@@ -210,11 +210,17 @@ func (a *Agent) clientConfig() (*clientconfig.Config, error) {
 	conf.Node.Meta = a.config.Client.Meta
 	conf.Node.NodeClass = a.config.Client.NodeClass
 	httpAddr := fmt.Sprintf("%s:%d", a.config.BindAddr, a.config.Ports.HTTP)
-	if a.config.Addresses.HTTP != "" && a.config.AdvertiseAddrs.HTTP == "" {
+	if a.config.Addresses.HTTP != "" && a.config.AdvertiseAddrs.HTTP == "" && a.config.Interfaces.HTTP == "" {
 		httpAddr = fmt.Sprintf("%s:%d", a.config.Addresses.HTTP, a.config.Ports.HTTP)
 		if _, err := net.ResolveTCPAddr("tcp", httpAddr); err != nil {
 			return nil, fmt.Errorf("error resolving http addr: %v:", err)
 		}
+	} else if a.config.Interfaces.HTTP != "" && a.config.AdvertiseAddrs.HTTP == "" {
+		ip, err := ipOfDevice(a.config.Interfaces.HTTP)
+		if err != nil {
+			return nil, fmt.Errorf("error finding ip address from interface %q: %v", a.config.Interfaces.HTTP, err)
+		}
+		httpAddr = fmt.Sprintf("%s:%d", ip.String(), a.config.Ports.HTTP)
 	} else if a.config.AdvertiseAddrs.HTTP != "" {
 		addr, err := net.ResolveTCPAddr("tcp", a.config.AdvertiseAddrs.HTTP)
 		if err != nil {
diff --git a/command/agent/util.go b/command/agent/util.go
index 27df5f8f2..6645a0af9 100644
--- a/command/agent/util.go
+++ b/command/agent/util.go
@@ -13,7 +13,7 @@ func randomStagger(intv time.Duration) time.Duration {
 }
 
 // IpOfDevice returns a routable ip addr of a device
-func IpOfDevice(name string) (net.IP, error) {
+func ipOfDevice(name string) (net.IP, error) {
 	intf, err := net.InterfaceByName(name)
 	if err != nil {
 		return nil, err
@@ -25,13 +25,30 @@ func IpOfDevice(name string) (net.IP, error) {
 	if len(addrs) == 0 {
 		return nil, fmt.Errorf("no ips were detected on the interface: %v", name)
 	}
+	var ipv4Addrs []net.IP
+	var ipv6Addrs []net.IP
 	for _, addr := range addrs {
+		var ip net.IP
 		switch v := (addr).(type) {
 		case *net.IPNet:
 			continue
 		case *net.IPAddr:
-			return v.IP, nil
+			ip = v.IP
+			if ip.To4() != nil {
+				ipv4Addrs = append(ipv4Addrs, ip)
+				continue
+			}
+			if ip.To16() != nil {
+				ipv6Addrs = append(ipv6Addrs, ip)
+				continue
+			}
 		}
 	}
+	if len(ipv4Addrs) > 0 {
+		return ipv4Addrs[0], nil
+	}
+	if len(ipv6Addrs) > 0 {
+		return ipv6Addrs[0], nil
+	}
 	return nil, fmt.Errorf("no ips were detected on the interface: %v", name)
 }