volume: best effort to detect ip address

fix https://github.com/chrislusf/seaweedfs/issues/1264

weed/command/volume.go

@@ -127,7 +127,7 @@ func (v VolumeServerOptions) startVolumeServer(volumeFolders, maxVolumeCounts, v
 	}
 
 	if *v.ip == "" {
-		*v.ip = "127.0.0.1"
+		*v.ip = util.DetectedHostAddress()
 	}
 
 	if *v.publicPort == 0 {

weed/util/network.go

@@ -0,0 +1,25 @@
+package util
+
+import (
+	"net"
+
+	"github.com/chrislusf/seaweedfs/weed/glog"
+)
+
+func DetectedHostAddress() string {
+	addrs, err := net.InterfaceAddrs()
+	if err != nil {
+		glog.V(0).Infof("failed to detect ip address: %v", err)
+		return ""
+	}
+
+	for _, a := range addrs {
+		if ipnet, ok := a.(*net.IPNet); ok && !ipnet.IP.IsLoopback() {
+			if ipnet.IP.To4() != nil {
+				return ipnet.IP.String()
+			}
+		}
+	}
+
+	return "localhost"
+}