GetIPv4Address - A Go function to get your host's IPv4 address

gistfile1.txt

// GetIPv4Address returns this node's IPv4 IP Address
// If more than one IP address found, call GetPreferredOutboundIP
// 127.0.0.1 will be returned if no other IPv4 addresses are found;
// otherwise, the non 127.0.0.1 address will be returned
// Assumes node has at least one interface (and the 127.0.0.1 address)
// If any errors occur, 127.0.0.1 will be returned
func getIPv4Address() (net.IP, error) {
	ifaces, err := net.Interfaces()
	if err != nil {
		return nil, err
	}
	var ips []net.IP
	for _, iface := range ifaces {
		addrs, err := iface.Addrs()
		if err != nil {
			return nil, err
		}
		for _, addr := range addrs {
			var ip net.IP
			switch v := addr.(type) {
			case *net.IPNet:
				ip = v.IP
			case *net.IPAddr:
				ip = v.IP
			}
			if ip != nil {
				ips = append(ips, ip)
			}
		}
	}

	if len(ips) > 0 {
		for _, ip := range ips {
			if ip.To4() != nil && !ip.IsLoopback() {
				return ip.To4(), nil
			}
		}
	}

	return getPreferredOutboundIP()
}

// getPreferredOutboundIP gets the preferred outbound ip address
func getPreferredOutboundIP() (net.IP, error) {
	conn, err := net.Dial("udp", "9.9.9.9:9999")
	if err != nil {
		return nil, error
	}
	defer closeConn(conn)

	localAddr := conn.LocalAddr().(*net.UDPAddr)

	return localAddr.IP, nil
}