Move the bindAddress computation to config parsing

cluster.go

@@ -6,7 +6,6 @@ import (
 	"encoding/json"
 	"fmt"
 	"io/ioutil"
-	"net"
 	"os"
 	"path"
 	"time"
@@ -33,7 +32,7 @@ type cluster struct {
 
 const statePath = "/var/lib/wesher/state.json"
 
-func newCluster(init bool, clusterKey []byte, bindAddr string, bindIface string, bindPort int, useIPAsName bool, getMeta func(int) []byte) (*cluster, error) {
+func newCluster(init bool, clusterKey []byte, bindAddr string, bindPort int, useIPAsName bool, getMeta func(int) []byte) (*cluster, error) {
 	state := &ClusterState{}
 	if !init {
 		loadState(state)
@@ -44,11 +43,6 @@ func newCluster(init bool, clusterKey []byte, bindAddr string, bindIface string,
 		return nil, err
 	}
 
-	bindAddr, err = computeBindAddr(bindAddr, bindIface)
-	if err != nil {
-		return nil, err
-	}
-
 	mlConfig := memberlist.DefaultWANConfig()
 	mlConfig.LogOutput = logrus.StandardLogger().WriterLevel(logrus.DebugLevel)
 	mlConfig.SecretKey = clusterKey
@@ -175,25 +169,6 @@ func computeClusterKey(state *ClusterState, clusterKey []byte) ([]byte, error) {
 	return clusterKey, nil
 }
 
-func computeBindAddr(bindAddr string, bindIface string) (string, error) {
-	if bindIface != "" {
-		iface, err := net.InterfaceByName(bindIface)
-		if err != nil {
-			return "", err
-		}
-		addrs, err := iface.Addrs()
-		if err != nil {
-			return "", err
-		}
-		if len(addrs) > 0 {
-			if addr, ok := addrs[0].(*net.IPNet); ok {
-				bindAddr = addr.IP.String()
-			}
-		}
-	}
-	return bindAddr, nil
-}
-
 func (c *cluster) saveState() error {
 	if err := os.MkdirAll(path.Dir(statePath), 0700); err != nil {
 		return err

config.go

@@ -44,10 +44,26 @@ func loadConfig() (*config, error) {
 		return nil, fmt.Errorf("unsupported overlay network size; net mask must be multiple of 8, got %d", bits)
 	}
 
-	// FIXME: this is a workaround for memberlist refusing to listen on public IPs if BindAddr==0.0.0.0
 	if config.BindAddr != "" && config.BindIface != "" {
 		return nil, fmt.Errorf("setting both bind address and bind interface is not supported")
+
+	} else if config.BindIface != "" {
+		// Compute the actual bind address based on the provided interface
+		iface, err := net.InterfaceByName(config.BindIface)
+		if err != nil {
+			return nil, fmt.Errorf("cannot find interface %s", config.BindIface)
+		}
+		addrs, err := iface.Addrs()
+		if err != nil {
+			return nil, fmt.Errorf("no available ip address on interface %s", config.BindIface)
+		}
+		if len(addrs) > 0 {
+			if addr, ok := addrs[0].(*net.IPNet); ok {
+				config.BindAddr = addr.IP.String()
+			}
+		}
 	} else if config.BindAddr == "" && config.BindIface == "" {
+		// FIXME: this is a workaround for memberlist refusing to listen on public IPs if BindAddr==0.0.0.0
 		detectedBindAddr, err := sockaddr.GetPublicIP()
 		if err != nil {
 			return nil, err

main.go

@@ -42,7 +42,7 @@ func main() {
 		}, limit)
 	}
 
-	cluster, err := newCluster(config.Init, config.ClusterKey, config.BindAddr, config.BindIface, config.ClusterPort, config.UseIPAsName, getMeta)
+	cluster, err := newCluster(config.Init, config.ClusterKey, config.BindAddr, config.ClusterPort, config.UseIPAsName, getMeta)
 	if err != nil {
 		logrus.WithError(err).Fatal("could not create cluster")
 	}