Extract private ip for registration when 0.0.0.0 is specified as bind address

server/extractor.go

@@ -2,11 +2,24 @@ package server
 
 import (
 	"fmt"
+	"net"
 	"reflect"
 
 	"github.com/myodc/go-micro/registry"
 )
 
+var (
+	privateBlocks []*net.IPNet
+)
+
+func init() {
+	for _, b := range []string{"10.0.0.0/8", "172.16.0.0/12", "192.168.0.0/16"} {
+		if _, block, err := net.ParseCIDR(b); err == nil {
+			privateBlocks = append(privateBlocks, block)
+		}
+	}
+}
+
 func extractValue(v reflect.Type) *registry.Value {
 	if v == nil {
 		return nil
@@ -81,3 +94,55 @@ func extractSubValue(typ reflect.Type) *registry.Value {
 	}
 	return extractValue(reqType)
 }
+
+func extractAddress(addr string) (string, error) {
+	if len(addr) > 0 && (addr != "0.0.0.0" && addr != "[::]") {
+		return addr, nil
+	}
+
+	addrs, err := net.InterfaceAddrs()
+	if err != nil {
+		return "", fmt.Errorf("Failed to get interface addresses! Err: %v", err)
+	}
+
+	var ipAddr []byte
+
+	for _, rawAddr := range addrs {
+		var ip net.IP
+		switch addr := rawAddr.(type) {
+		case *net.IPAddr:
+			ip = addr.IP
+		case *net.IPNet:
+			ip = addr.IP
+		default:
+			continue
+		}
+
+		if ip.To4() == nil {
+			continue
+		}
+
+		if !isPrivateIP(ip.String()) {
+			continue
+		}
+
+		ipAddr = ip
+		break
+	}
+
+	if ipAddr == nil {
+		return "", fmt.Errorf("No private IP address found, and explicit IP not provided")
+	}
+
+	return net.IP(ipAddr).String(), nil
+}
+
+func isPrivateIP(ipAddr string) bool {
+	ip := net.ParseIP(ipAddr)
+	for _, priv := range privateBlocks {
+		if priv.Contains(ip) {
+			return true
+		}
+	}
+	return false
+}

server/rpc_server.go

@@ -116,6 +116,7 @@ func (s *rpcServer) Register() error {
 	config := s.Config()
 	var host string
 	var port int
+
 	parts := strings.Split(config.Address(), ":")
 	if len(parts) > 1 {
 		host = strings.Join(parts[:len(parts)-1], ":")
@@ -124,10 +125,15 @@ func (s *rpcServer) Register() error {
 		host = parts[0]
 	}
 
+	addr, err := extractAddress(host)
+	if err != nil {
+		return err
+	}
+
 	// register service
 	node := &registry.Node{
 		Id:       config.Id(),
-		Address:  host,
+		Address:  addr,
 		Port:     port,
 		Metadata: config.Metadata(),
 	}
@@ -181,9 +187,14 @@ func (s *rpcServer) Deregister() error {
 		host = parts[0]
 	}
 
+	addr, err := extractAddress(host)
+	if err != nil {
+		return err
+	}
+
 	node := &registry.Node{
 		Id:      config.Id(),
-		Address: host,
+		Address: addr,
 		Port:    port,
 	}