feat: add service.beta.kubernetes.io/scw-loadbalancer-flexible-ip-types annotation (#256)

Author: Tomy2e

docs/loadbalancer-annotations.md

@@ -229,6 +229,16 @@ The possible formats are:
 - `<ip-id>`: will attach a single IP to the LB.
 - `<ip-id>,<ip-id>`: will attach the two IPs to the LB.
 
+### `service.beta.kubernetes.io/scw-loadbalancer-flexible-ip-types`
+
+This is the annotation to choose which flexible IP(s) to book when the LB is created.
+It is a comma delimited list of IP types. The default value is `ipv4` and the possible
+values are `ipv4` or `ipv4,ipv6`.
+A flexible IPv4 is always required, an IPv6-only LB is not supported.
+This annotation is only taken into account at LB creation, and has no effect on an
+already existing LB. It is ignored if `service.beta.kubernetes.io/scw-loadbalancer-ip-ids`
+is set, since in that case the provided IP(s) are used instead of booking new ones.
+
 ### `service.beta.kubernetes.io/scw-loadbalancer-private-ip-ids`
 
 This is the annotation to statically set the private IPs of the loadbalancer.

scaleway/loadbalancers.go

@@ -480,11 +480,20 @@ func (l *loadbalancers) createLoadBalancer(ctx context.Context, service *v1.Serv
 
 	// Attach specific IP if set
 	var ipIDs []string
+	var assignFlexibleIP, assignFlexibleIPv6 bool
 	if !lbPrivate {
 		ipIDs, err = l.getLoadBalancerStaticIPIDs(ctx, service)
 		if err != nil {
 			return nil, err
 		}
+
+		// We must only assign flexible IP(s) if no IP ID is provided.
+		if len(ipIDs) == 0 {
+			assignFlexibleIP, assignFlexibleIPv6, err = getFlexibleIPTypes(service)
+			if err != nil {
+				return nil, fmt.Errorf("invalid value for annotation %s: %w", serviceAnnotationLoadBalancerFlexibleIPTypes, err)
+			}
+		}
 	}
 
 	lbName := l.GetLoadBalancerName(ctx, "", service)
@@ -510,9 +519,10 @@ func (l *loadbalancers) createLoadBalancer(ctx context.Context, service *v1.Serv
 		Tags:        tags,
 		IPIDs:       ipIDs,
 		Type:        lbType,
-		// We must only assign a flexible IP if LB is public AND no IP ID is provided.
+		// We must only assign flexible IP(s) if LB is public AND no IP ID is provided.
 		// If IP IDs are provided, there must be at least one IPv4.
-		AssignFlexibleIP:      scw.BoolPtr(!lbPrivate && len(ipIDs) == 0),
+		AssignFlexibleIP:      new(assignFlexibleIP),
+		AssignFlexibleIPv6:    new(assignFlexibleIPv6),
 		SslCompatibilityLevel: sslCompatibilityLevel,
 	}
 	lb, err := l.api.CreateLB(&request, scw.WithContext(ctx))

scaleway/loadbalancers_annotations.go

@@ -1,6 +1,7 @@
 package scaleway
 
 import (
+	"errors"
 	"fmt"
 	"net/url"
 	"slices"
@@ -253,6 +254,13 @@ const (
 	//	- "<pn-id>,<pn-id>": will attach the two Private Networks to the LB.
 	serviceAnnotationPrivateNetworkIDs = "service.beta.kubernetes.io/scw-loadbalancer-pn-ids"
 
+	// serviceAnnotationLoadBalancerFlexibleIPTypes is the annotation to choose which flexible IP(s) to book for the LB
+	// when it is created and no static IP is provided via service.beta.kubernetes.io/scw-loadbalancer-ip-ids.
+	// The default value is "ipv4" and the possible values are "ipv4" or "ipv4,ipv6".
+	// A flexible IPv4 is always required, an IPv6-only LB is not supported.
+	// This annotation is only used at LB creation and has no effect on an already existing LB.
+	serviceAnnotationLoadBalancerFlexibleIPTypes = "service.beta.kubernetes.io/scw-loadbalancer-flexible-ip-types"
+
 	// serviceAnnotationLoadBalancerHealthCheckFromService is the annotation to use healthCheckNodePort from the service
 	// The possible values are "false", "true" or "*" for all ports or a comma delimited list of the service port
 	// (for instance "80,443"). When enabled for a port, the health check will use the service's healthCheckNodePort
@@ -329,6 +337,32 @@ func getIPIDs(service *v1.Service) []string {
 	return strings.Split(ipIDs, ",")
 }
 
+// getFlexibleIPTypes returns whether a flexible IPv4 and/or a flexible IPv6 should be
+// booked for the LB, based on the serviceAnnotationLoadBalancerFlexibleIPTypes annotation.
+func getFlexibleIPTypes(service *v1.Service) (assignIPv4 bool, assignIPv6 bool, err error) {
+	flexibleIPTypes := service.Annotations[serviceAnnotationLoadBalancerFlexibleIPTypes]
+	if flexibleIPTypes == "" {
+		return true, false, nil
+	}
+
+	for ipType := range strings.SplitSeq(flexibleIPTypes, ",") {
+		switch strings.ToLower(strings.TrimSpace(ipType)) {
+		case "ipv4":
+			assignIPv4 = true
+		case "ipv6":
+			assignIPv6 = true
+		default:
+			return false, false, fmt.Errorf("unsupported value %q", strings.ToLower(strings.TrimSpace(ipType)))
+		}
+	}
+
+	if !assignIPv4 {
+		return false, false, errors.New("an IPv4 is always required")
+	}
+
+	return assignIPv4, assignIPv6, nil
+}
+
 func getPrivateIPIDs(service *v1.Service) sets.Set[string] {
 	privateIPIDs := service.Annotations[serviceAnnotationLoadBalancerPrivateIPIDs]
 	if privateIPIDs == "" {

scaleway/loadbalancers_test.go

@@ -2185,6 +2185,107 @@ func TestGetSSLCompatibilityLevel(t *testing.T) {
 	}
 }
 
+func TestGetFlexibleIPTypes(t *testing.T) {
+	matrix := []struct {
+		name     string
+		service  *v1.Service
+		wantIPv4 bool
+		wantIPv6 bool
+		wantErr  bool
+	}{
+		{
+			"with no annotation",
+			&v1.Service{
+				ObjectMeta: metav1.ObjectMeta{
+					Annotations: map[string]string{},
+				},
+			},
+			true,
+			false,
+			false,
+		},
+		{
+			"with ipv4",
+			&v1.Service{
+				ObjectMeta: metav1.ObjectMeta{
+					Annotations: map[string]string{
+						"service.beta.kubernetes.io/scw-loadbalancer-flexible-ip-types": "ipv4",
+					},
+				},
+			},
+			true,
+			false,
+			false,
+		},
+		{
+			"with ipv6 only (unsupported)",
+			&v1.Service{
+				ObjectMeta: metav1.ObjectMeta{
+					Annotations: map[string]string{
+						"service.beta.kubernetes.io/scw-loadbalancer-flexible-ip-types": "ipv6",
+					},
+				},
+			},
+			false,
+			false,
+			true,
+		},
+		{
+			"with ipv4,ipv6",
+			&v1.Service{
+				ObjectMeta: metav1.ObjectMeta{
+					Annotations: map[string]string{
+						"service.beta.kubernetes.io/scw-loadbalancer-flexible-ip-types": "ipv4,ipv6",
+					},
+				},
+			},
+			true,
+			true,
+			false,
+		},
+		{
+			"with spaces and uppercase values",
+			&v1.Service{
+				ObjectMeta: metav1.ObjectMeta{
+					Annotations: map[string]string{
+						"service.beta.kubernetes.io/scw-loadbalancer-flexible-ip-types": "IPV4, IPV6",
+					},
+				},
+			},
+			true,
+			true,
+			false,
+		},
+		{
+			"with invalid value",
+			&v1.Service{
+				ObjectMeta: metav1.ObjectMeta{
+					Annotations: map[string]string{
+						"service.beta.kubernetes.io/scw-loadbalancer-flexible-ip-types": "invalid",
+					},
+				},
+			},
+			false,
+			false,
+			true,
+		},
+	}
+
+	for _, tt := range matrix {
+		t.Run(tt.name, func(t *testing.T) {
+			gotIPv4, gotIPv6, err := getFlexibleIPTypes(tt.service)
+			if tt.wantErr != (err != nil) {
+				t.Errorf("got error: %s, expected: %v", err, tt.wantErr)
+				return
+			}
+
+			if gotIPv4 != tt.wantIPv4 || gotIPv6 != tt.wantIPv6 {
+				t.Errorf("want: (%v, %v), got: (%v, %v)", tt.wantIPv4, tt.wantIPv6, gotIPv4, gotIPv6)
+			}
+		})
+	}
+}
+
 func Test_ipMode(t *testing.T) {
 	type args struct {
 		service *v1.Service