Migrate netutil methods into /util/net.go

pkg/cli/agent/agent.go

@@ -11,8 +11,8 @@ import (
 	"github.com/k3s-io/k3s/pkg/agent"
 	"github.com/k3s-io/k3s/pkg/cli/cmds"
 	"github.com/k3s-io/k3s/pkg/datadir"
-	"github.com/k3s-io/k3s/pkg/netutil"
 	"github.com/k3s-io/k3s/pkg/token"
+	"github.com/k3s-io/k3s/pkg/util"
 	"github.com/k3s-io/k3s/pkg/version"
 	"github.com/rancher/wrangler/pkg/signals"
 	"github.com/sirupsen/logrus"
@@ -60,7 +60,7 @@ func Run(ctx *cli.Context) error {
 	}
 
 	if cmds.AgentConfig.FlannelIface != "" && len(cmds.AgentConfig.NodeIP) == 0 {
-		cmds.AgentConfig.NodeIP.Set(netutil.GetIPFromInterface(cmds.AgentConfig.FlannelIface))
+		cmds.AgentConfig.NodeIP.Set(util.GetIPFromInterface(cmds.AgentConfig.FlannelIface))
 	}
 
 	logrus.Info("Starting " + version.Program + " agent " + ctx.App.Version)

pkg/cli/server/server.go

@@ -18,7 +18,6 @@ import (
 	"github.com/k3s-io/k3s/pkg/daemons/config"
 	"github.com/k3s-io/k3s/pkg/datadir"
 	"github.com/k3s-io/k3s/pkg/etcd"
-	"github.com/k3s-io/k3s/pkg/netutil"
 	"github.com/k3s-io/k3s/pkg/rootless"
 	"github.com/k3s-io/k3s/pkg/server"
 	"github.com/k3s-io/k3s/pkg/token"
@@ -201,7 +200,7 @@ func run(app *cli.Context, cfg *cmds.Server, leaderControllers server.CustomCont
 	}
 
 	if cmds.AgentConfig.FlannelIface != "" && len(cmds.AgentConfig.NodeIP) == 0 {
-		cmds.AgentConfig.NodeIP.Set(netutil.GetIPFromInterface(cmds.AgentConfig.FlannelIface))
+		cmds.AgentConfig.NodeIP.Set(util.GetIPFromInterface(cmds.AgentConfig.FlannelIface))
 	}
 
 	if serverConfig.ControlConfig.PrivateIP == "" && len(cmds.AgentConfig.NodeIP) != 0 {

pkg/util/net.go

@@ -7,6 +7,7 @@ import (
 	"os"
 	"strings"
 
+	"github.com/sirupsen/logrus"
 	"github.com/urfave/cli"
 	apinet "k8s.io/apimachinery/pkg/util/net"
 )
@@ -299,3 +300,61 @@ func IPStringToIPNet(address string) (*net.IPNet, error) {
 	_, cidr, err := net.ParseCIDR(address)
 	return cidr, err
 }
+
+// GetIPFromInterface is the public function that returns the IP of an interface
+func GetIPFromInterface(ifaceName string) string {
+	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 ip
+}
+
+// getIPFromInterface is the private function that returns de IP of an interface
+func getIPFromInterface(ifaceName string) (string, error) {
+	iface, err := net.InterfaceByName(ifaceName)
+	if err != nil {
+		return "", err
+	}
+	addrs, err := iface.Addrs()
+	if err != nil {
+		return "", err
+	}
+	if iface.Flags&net.FlagUp == 0 {
+		return "", fmt.Errorf("the interface %s is not up", ifaceName)
+	}
+
+	globalUnicasts := []string{}
+	globalUnicastsIPv6 := []string{}
+	for _, addr := range addrs {
+		ip, _, err := net.ParseCIDR(addr.String())
+		if err != nil {
+			return "", fmt.Errorf("unable to parse CIDR for interface %s: %w", iface.Name, err)
+		}
+		// if not IPv4 adding it on IPv6 list
+		if ip.To4() == nil {
+			if ip.IsGlobalUnicast() {
+				globalUnicastsIPv6 = append(globalUnicastsIPv6, ip.String())
+			}
+			continue
+		}
+		if ip.IsGlobalUnicast() {
+			globalUnicasts = append(globalUnicasts, ip.String())
+		}
+	}
+
+	if len(globalUnicasts) > 1 {
+		return "", fmt.Errorf("multiple global unicast addresses defined for %s, please set ip from one of %v", ifaceName, globalUnicasts)
+	}
+	if len(globalUnicasts) == 1 && len(globalUnicastsIPv6) == 0 {
+		return globalUnicasts[0], nil
+	} else if len(globalUnicastsIPv6) > 0 && len(globalUnicasts) == 1 {
+		return globalUnicasts[0] + "," + globalUnicastsIPv6[0], nil
+	} else if len(globalUnicastsIPv6) > 0 {
+		return globalUnicastsIPv6[0], nil
+	}
+
+	return "", fmt.Errorf("can't find ip for interface %s", ifaceName)
+}