[fix] Ignore ipv6 routes (#368)

* Add local cache of 'configured' IPv6 routes to send to cloud-provider
* Added unit tests for CreateRoute

Author: Andrews2024

cloud/linode/route_controller.go

@@ -3,6 +3,7 @@ package linode
 import (
 	"context"
 	"fmt"
+	"net"
 	"os"
 	"strconv"
 	"strings"
@@ -19,6 +20,8 @@ import (
 	"github.com/linode/linode-cloud-controller-manager/cloud/linode/client"
 )
 
+var ipv6ConfiguredRoutes []*cloudprovider.Route
+
 type routeCache struct {
 	Mu         sync.RWMutex
 	routes     map[int][]linodego.VPCIP
@@ -128,6 +131,17 @@ func (r *routes) getInstanceFromName(ctx context.Context, name string) (*linodeg
 
 // CreateRoute adds route's subnet to ip_ranges of target node's VPC interface
 func (r *routes) CreateRoute(ctx context.Context, clusterName string, nameHint string, route *cloudprovider.Route) error {
+	// ignore IPv6 CIDRs but make sure something gets assigned to them to avoid errors
+	ipAddr, _, err := net.ParseCIDR(route.DestinationCIDR)
+	if err != nil {
+		return err
+	}
+	if ipAddr.To4() == nil {
+		// "configure" the route so route controller doesn't keep creating it
+		ipv6ConfiguredRoutes = append(ipv6ConfiguredRoutes, route)
+		return nil
+	}
+
 	instance, err := r.getInstanceFromName(ctx, string(route.TargetNode))
 	if err != nil {
 		return err
@@ -272,5 +286,9 @@ func (r *routes) ListRoutes(ctx context.Context, clusterName string) ([]*cloudpr
 			}
 		}
 	}
+
+	// add in "configured" IPv6 routes so cloud-provider is happy
+	configuredRoutes = append(configuredRoutes, ipv6ConfiguredRoutes...)
+
 	return configuredRoutes, nil
 }

cloud/linode/route_controller_test.go

@@ -381,6 +381,40 @@ func TestCreateRoute(t *testing.T) {
 		assert.NoError(t, err)
 	})
 
+	v6Route := &cloudprovider.Route{
+		Name:            "route2",
+		TargetNode:      types.NodeName(name),
+		DestinationCIDR: "fd00::/64",
+	}
+	t.Run("should return no error if given a route with an IPv6 address", func(t *testing.T) {
+		ctrl := gomock.NewController(t)
+		defer ctrl.Finish()
+		client := mocks.NewMockClient(ctrl)
+		instanceCache := newInstances(client)
+		routeController, err := newRoutes(client, instanceCache)
+		require.NoError(t, err)
+
+		err = routeController.CreateRoute(ctx, "dummy", "dummy", v6Route)
+		assert.NoError(t, err)
+	})
+
+	badV6Route := &cloudprovider.Route{
+		Name:            "route2",
+		TargetNode:      types.NodeName(name),
+		DestinationCIDR: ":/64",
+	}
+	t.Run("should return error if IP address is not v4 or v6", func(t *testing.T) {
+		ctrl := gomock.NewController(t)
+		defer ctrl.Finish()
+		client := mocks.NewMockClient(ctrl)
+		instanceCache := newInstances(client)
+		routeController, err := newRoutes(client, instanceCache)
+		require.NoError(t, err)
+
+		err = routeController.CreateRoute(ctx, "dummy", "dummy", badV6Route)
+		assert.Error(t, err)
+	})
+
 	addressRange1 := "10.10.10.0/24"
 	routesInVPC := []linodego.VPCIP{
 		{