Include the interface name in the error message

pkg/agent/config/config.go

@@ -363,7 +363,7 @@ func get(ctx context.Context, envInfo *cmds.Agent, proxy proxy.Proxy) (*config.N
 	if controlConfig.FlannelBackend != config.FlannelBackendNone && len(envInfo.FlannelIface) > 0 {
 		flannelIface, err = net.InterfaceByName(envInfo.FlannelIface)
 		if err != nil {
-			return nil, errors.Wrapf(err, "unable to find interface")
+			return nil, errors.Wrapf(err, "unable to find interface %s", envInfo.FlannelIface)
 		}
 	}
 

pkg/cli/agent/agent.go

@@ -60,7 +60,11 @@ func Run(ctx *cli.Context) error {
 	}
 
 	if cmds.AgentConfig.FlannelIface != "" && len(cmds.AgentConfig.NodeIP) == 0 {
-		cmds.AgentConfig.NodeIP.Set(util.GetIPFromInterface(cmds.AgentConfig.FlannelIface))
+		ip, err :=  util.GetIPFromInterface(cmds.AgentConfig.FlannelIface)
+		if err != nil {
+			return err
+		}
+		cmds.AgentConfig.NodeIP.Set(ip)
 	}
 
 	logrus.Info("Starting " + version.Program + " agent " + ctx.App.Version)

pkg/cli/server/server.go

@@ -217,7 +217,11 @@ func run(app *cli.Context, cfg *cmds.Server, leaderControllers server.CustomCont
 	}
 
 	if cmds.AgentConfig.FlannelIface != "" && len(cmds.AgentConfig.NodeIP) == 0 {
-		cmds.AgentConfig.NodeIP.Set(util.GetIPFromInterface(cmds.AgentConfig.FlannelIface))
+		ip, err :=  util.GetIPFromInterface(cmds.AgentConfig.FlannelIface)
+		if err != nil {
+			return err
+		}
+		cmds.AgentConfig.NodeIP.Set(ip)
 	}
 
 	if serverConfig.ControlConfig.PrivateIP == "" && len(cmds.AgentConfig.NodeIP) != 0 {

pkg/util/net.go

@@ -301,14 +301,13 @@ func IPStringToIPNet(address string) (*net.IPNet, error) {
 }
 
 // GetIPFromInterface is the public function that returns the IP of an interface
-func GetIPFromInterface(ifaceName string) string {
+func GetIPFromInterface(ifaceName string) (string, error) {
 	ip, err := getIPFromInterface(ifaceName)
 	if err != nil {
-		logrus.Warn(fmt.Errorf("unable to get global unicast ip from interface name: %w", err))
-	} else {
-		logrus.Infof("Found ip %s from iface %s", ip, ifaceName)
+		return "", fmt.Errorf("interface %s does not have a correct global unicast ip: %w", ifaceName, err)
 	}
-	return ip
+	logrus.Infof("Found ip %s from iface %s", ip, ifaceName)
+	return ip, nil
 }
 
 // getIPFromInterface is the private function that returns de IP of an interface