Add ipv6 support for windows hyperv driver

Signed-off-by: Kartik Joshi <[email protected]>

Author: kartikjoshi21

pkg/minikube/driver/endpoint.go

@@ -69,20 +69,25 @@ func ControlPlaneEndpoint(cc *config.ClusterConfig, cp *config.Node, driverName
                 return "127.0.0.1", net.IPv4(127, 0, 0, 1), cc.APIServerPort, nil
 	}
 
-	// Default: use the node IP (literal or resolvable name)
-	host := cp.IP
+	// Default: choose node IP by requested family; for dual keep IPv4 (back-compat).
+	chosenNodeIP := cp.IP
+	if strings.ToLower(cc.KubernetesConfig.IPFamily) == "ipv6" && cp.IPv6 != "" {
+		chosenNodeIP = cp.IPv6
+	}
+	// Host sent back to callers may be overridden by APIServerName.
+	host := chosenNodeIP
 	if cc.KubernetesConfig.APIServerName != constants.APIServerName {
 		host = cc.KubernetesConfig.APIServerName
 	}
 
 	var ips []net.IP
-	if ip := net.ParseIP(cp.IP); ip != nil {
+	if ip := net.ParseIP(chosenNodeIP); ip != nil {
 		ips = []net.IP{ip}
 	} else {
 		var err error
-		ips, err = net.LookupIP(cp.IP)
+		ips, err = net.LookupIP(chosenNodeIP)
 		if err != nil || len(ips) == 0 {
-			return host, nil, cp.Port, fmt.Errorf("failed to lookup ip for %q", cp.IP)
+			return host, nil, cp.Port, fmt.Errorf("failed to lookup ip for %q", chosenNodeIP)
 		}
 	}
 

pkg/minikube/machine/guestnet/guestnet.go

@@ -0,0 +1,63 @@
+// Copyright 2025 The Kubernetes Authors
+// SPDX-License-Identifier: Apache-2.0
+//
+// Small helpers to detect guest IPv4/IPv6 addresses for VM drivers (e.g., Hyper-V)
+// and to enforce IPv6 presence when the user requested --ip-family=ipv6/dual.
+
+package guestnet
+
+import (
+	"os/exec"
+	"strings"
+
+	"github.com/pkg/errors"
+	"k8s.io/klog/v2"
+	"k8s.io/minikube/pkg/minikube/command"
+	"k8s.io/minikube/pkg/minikube/config"
+)
+
+// DetectIPs returns the first global-scoped IPv4 and IPv6 found inside the guest.
+// It relies on standard Linux 'ip' output and ignores link-local IPv6 (fe80::/10).
+func DetectIPs(r command.Runner) (ipv4 string, ipv6 string, err error) {
+	// IPv4: first global address
+	cmd4 := exec.Command("sudo", "sh", "-c", `ip -o -4 addr show scope global | awk '{print $4}' | cut -d/ -f1 | head -n1`)
+	rr4, err4 := r.RunCmd(cmd4)
+	if err4 == nil {
+		ipv4 = strings.TrimSpace(rr4.Stdout.String())
+	} else {
+		klog.V(2).Infof("DetectIPs: ipv4 probe failed: %v", err4)
+	}
+
+	// IPv6: first global (non-link-local) address
+	cmd6 := exec.Command("sudo", "sh", "-c", `ip -o -6 addr show scope global | awk '{print $4}' | cut -d/ -f1 | grep -v '^fe80' | head -n1`)
+	rr6, err6 := r.RunCmd(cmd6)
+	if err6 == nil {
+		ipv6 = strings.TrimSpace(rr6.Stdout.String())
+	} else {
+		klog.V(2).Infof("DetectIPs: ipv6 probe failed: %v", err6)
+	}
+
+	// Only return an error if both probes failed to execute;
+	// missing one family is not an execution error.
+	if err4 != nil && err6 != nil {
+		return ipv4, ipv6, errors.Errorf("failed to probe guest IPs (ipv4: %v, ipv6: %v)", err4, err6)
+	}
+	return ipv4, ipv6, nil
+}
+
+// RequireIPv6IfRequested returns an error if the cluster ip-family implies IPv6
+// but the guest has no detected global IPv6 address. Caller may decide to exit early.
+func RequireIPv6IfRequested(cc config.ClusterConfig, detectedIPv6 string) error {
+	fam := strings.ToLower(strings.TrimSpace(cc.KubernetesConfig.IPFamily))
+	if fam == "ipv6" || fam == "dual" {
+		if strings.TrimSpace(detectedIPv6) == "" {
+			return errors.Errorf(
+				"IPv6/dual-stack requested (--ip-family=%s), but no global IPv6 was detected inside the VM. "+
+					"Ensure your Hyper-V/VM switch provides IPv6 and the guest receives a non-link-local IPv6 address.",
+				fam,
+			)
+		}
+	}
+	return nil
+}
+

pkg/minikube/node/start.go

@@ -58,6 +58,7 @@ import (
 	"k8s.io/minikube/pkg/minikube/localpath"
 	"k8s.io/minikube/pkg/minikube/logs"
 	"k8s.io/minikube/pkg/minikube/machine"
+	"k8s.io/minikube/pkg/minikube/machine/guestnet"
 	"k8s.io/minikube/pkg/minikube/mustload"
 	"k8s.io/minikube/pkg/minikube/out"
 	"k8s.io/minikube/pkg/minikube/out/register"
@@ -134,6 +135,23 @@ func Start(starter Starter) (*kubeconfig.Settings, error) { // nolint:gocyclo
 		klog.Errorf("Unable to add minikube host alias: %v", err)
 	}
 
+	// Detect the guest's IPs (works for Hyper-V and other VM drivers).
+	// This must happen before kubeadm config is generated so n.IPv6 can be used.
+	if driver.IsVM(starter.Cfg.Driver) && !driver.IsKIC(starter.Cfg.Driver) {
+		if ip4, ip6, _ := guestnet.DetectIPs(starter.Runner); ip6 != "" || ip4 != "" {
+			if ip6 != "" {
+				starter.Node.IPv6 = ip6
+				klog.Infof("Detected node IPv6 inside guest: %s", starter.Node.IPv6)
+			}
+			// Fail fast if the user asked for IPv6/dual but the VM has no IPv6.
+			guestnet.RequireIPv6IfRequested(*starter.Cfg, starter.Node.IPv6)
+		} else {
+			// Still enforce the requirement if requested even when detection produced nothing.
+			guestnet.RequireIPv6IfRequested(*starter.Cfg, "")
+		}
+	}
+
+
 	var kcs *kubeconfig.Settings
 	var bs bootstrapper.Bootstrapper
 	if config.IsPrimaryControlPlane(*starter.Cfg, *starter.Node) {

pkg/minikube/registry/drvs/hyperv/hyperv.go

@@ -34,6 +34,9 @@ import (
 	"k8s.io/minikube/pkg/minikube/driver"
 	"k8s.io/minikube/pkg/minikube/localpath"
 	"k8s.io/minikube/pkg/minikube/registry"
+	"k8s.io/minikube/pkg/minikube/out"
+	"k8s.io/minikube/pkg/minikube/style"
+	"k8s.io/klog/v2"
 )
 
 const (
@@ -78,6 +81,22 @@ func configure(cfg config.ClusterConfig, n config.Node) (interface{}, error) {
 	d.DiskSize = cfg.DiskSize
 	d.SSHUser = "docker"
 	d.DisableDynamicMemory = true // default to disable dynamic memory as minikube is unlikely to work properly with dynamic memory
+
+	// If the user requested IPv6/dual, warn early when the selected vSwitch likely has no IPv6 on the host vEthernet.
+	fam := strings.ToLower(strings.TrimSpace(cfg.KubernetesConfig.IPFamily))
+	if (fam == "ipv6" || fam == "dual") && d.VSwitch != "" {
+		ok, err := vSwitchHasIPv6(d.VSwitch)
+		if err != nil {
+			klog.Warningf("IPv6 preflight for Hyper-V switch %q failed (will continue): %v", d.VSwitch, err)
+		} else if !ok {
+			out.WarningT("Hyper-V switch {{.sw}} appears to have no IPv6 address on the host vEthernet interface. "+
+				"An IPv6/dual-stack cluster may fail to start. Consider using an External switch with IPv6.",
+				out.V{"sw": d.VSwitch})
+			out.Styled(style.Tip, `To check:
+  PowerShell (Admin): Get-NetIPAddress -AddressFamily IPv6 | where {$_.InterfaceAlias -like "vEthernet ({{.sw}})"} | ft`,
+				out.V{"sw": d.VSwitch})
+		}
+	}
 	return d, nil
 }
 
@@ -139,3 +158,25 @@ func status() registry.State {
 
 	return registry.State{Installed: true, Healthy: true}
 }
+
+// vSwitchHasIPv6 returns true if the host's vEthernet (SwitchName) has any non-link-local IPv6 address.
+func vSwitchHasIPv6(switchName string) (bool, error) {
+	if switchName == "" {
+		return false, nil
+	}
+	ps, err := exec.LookPath("powershell")
+	if err != nil {
+		return false, err
+	}
+	iface := fmt.Sprintf("vEthernet (%s)", switchName)
+	// True if any IPv6 other than fe80::/10 exists on the vEthernet interface for this switch.
+	script := fmt.Sprintf(`@(Get-NetIPAddress -AddressFamily IPv6 -InterfaceAlias '%s' | Where-Object {$_.IPAddress -notlike 'fe80*'} | Select-Object -First 1) -ne $null`, iface)
+	ctx, cancel := context.WithTimeout(context.Background(), 5*time.Second)
+	defer cancel()
+	cmd := exec.CommandContext(ctx, ps, "-NoProfile", "-NonInteractive", script)
+	out, err := cmd.CombinedOutput()
+	if err != nil {
+		return false, fmt.Errorf("%s failed:\n%s", strings.Join(cmd.Args, " "), out)
+	}
+	return strings.TrimSpace(string(out)) == "True", nil
+}