Add IPv6 support for EndpointSlice creation and port replacement

The autoscaler stat forwarder hardcoded AddressTypeIPv4 when creating
EndpointSlices, which breaks on IPv6-only or dual-stack clusters.
Additionally, useSecurePort used strings.Split on ":" to extract the
host, which breaks on bracketed IPv6 addresses like [::1]:8012.

Changes:
- Add addressTypeForIP helper to dynamically determine AddressType
- Fix useSecurePort to use net.SplitHostPort/net.JoinHostPort
- Add tests for both functions with IPv4 and IPv6 cases

Signed-off-by: Vincent Link <vlink@redhat.com>

Author: linkvt

pkg/activator/handler/handler.go

@@ -20,6 +20,7 @@ import (
 	"context"
 	"errors"
 	"fmt"
+	"net"
 	"net/http"
 	"net/http/httputil"
 	"strconv"
@@ -184,8 +185,11 @@ func (a *activationHandler) proxyRequest(revID types.NamespacedName, w http.Resp
 // TODO: endpointsToDests() should support HTTPS instead of this overwrite but it needs metadata request to be encrypted.
 // This code should be removed when https://github.com/knative/serving/issues/12821 was solved.
 func useSecurePort(target string, port int) string {
-	target = strings.Split(target, ":")[0]
-	return target + ":" + strconv.Itoa(port)
+	host, _, err := net.SplitHostPort(target)
+	if err != nil {
+		host = target
+	}
+	return net.JoinHostPort(host, strconv.Itoa(port))
 }
 
 func WrapActivatorHandlerWithFullDuplex(h http.Handler, logger *zap.SugaredLogger) http.HandlerFunc {

pkg/activator/handler/handler_test.go

@@ -290,6 +290,34 @@ func setupConfigStore(t testing.TB, logger *zap.SugaredLogger) *activatorconfig.
 	return configStore
 }
 
+func TestUseSecurePort(t *testing.T) {
+	tests := map[string]struct {
+		target string
+		port   int
+		want   string
+	}{
+		"ipv4": {
+			target: "10.0.0.1:8012",
+			port:   8112,
+			want:   "10.0.0.1:8112",
+		},
+		"ipv6": {
+			target: "[2001:db8::1]:8012",
+			port:   8112,
+			want:   "[2001:db8::1]:8112",
+		},
+	}
+
+	for name, tc := range tests {
+		t.Run(name, func(t *testing.T) {
+			got := useSecurePort(tc.target, tc.port)
+			if got != tc.want {
+				t.Errorf("useSecurePort(%q, %d) = %q, want %q", tc.target, tc.port, got, tc.want)
+			}
+		})
+	}
+}
+
 func BenchmarkHandler(b *testing.B) {
 	ctx, cancel, _ := rtesting.SetupFakeContextWithCancel(b)
 	b.Cleanup(cancel)

pkg/autoscaler/statforwarder/forwarder_test.go

@@ -509,3 +509,28 @@ func TestIsBucketOwner(t *testing.T) {
 		t.Errorf("IsBktOwner(not-in-record) = %v, want true", got)
 	}
 }
+
+func TestAddressTypeForIP(t *testing.T) {
+	tests := map[string]struct {
+		ip   string
+		want discoveryv1.AddressType
+	}{
+		"ipv4": {
+			ip:   "10.0.0.1",
+			want: discoveryv1.AddressTypeIPv4,
+		},
+		"ipv6": {
+			ip:   "2001:db8::1",
+			want: discoveryv1.AddressTypeIPv6,
+		},
+	}
+
+	for name, tc := range tests {
+		t.Run(name, func(t *testing.T) {
+			got := addressTypeForIP(tc.ip)
+			if got != tc.want {
+				t.Errorf("addressTypeForIP(%q) = %v, want %v", tc.ip, got, tc.want)
+			}
+		})
+	}
+}

pkg/autoscaler/statforwarder/leases.go

@@ -245,7 +245,7 @@ func (f *leaseTracker) createOrUpdateEndpoints(ctx context.Context, ns, n string
 				discoveryv1.LabelServiceName: n,
 			},
 		},
-		AddressType: discoveryv1.AddressTypeIPv4,
+		AddressType: addressTypeForIP(f.selfIP),
 		Endpoints: []discoveryv1.Endpoint{{
 			Addresses: []string{f.selfIP},
 			Conditions: discoveryv1.EndpointConditions{
@@ -307,3 +307,11 @@ func (f *leaseTracker) createOrUpdateEndpoints(ctx context.Context, ns, n string
 
 	return nil
 }
+
+func addressTypeForIP(ip string) discoveryv1.AddressType {
+	parsed := net.ParseIP(ip)
+	if parsed == nil || parsed.To4() != nil {
+		return discoveryv1.AddressTypeIPv4
+	}
+	return discoveryv1.AddressTypeIPv6
+}