AWS: Remove blackhole routes in our managed range

Blackhole routes otherwise acccumulate unboundedly.  We also are careful
to ensure that we do so only within the managed range, which requires
enlisting the help of the routecontroller.

Fix #47524

pkg/cloudprovider/cloud.go

@@ -150,6 +150,9 @@ type Route struct {
 	// DestinationCIDR is the CIDR format IP range that this routing rule
 	// applies to.
 	DestinationCIDR string
+	// Blackhole is set to true if this is a blackhole route
+	// The node controller will delete the route if it is in the managed range.
+	Blackhole bool
 }
 
 // Routes is an abstract, pluggable interface for advanced routing rules.

pkg/cloudprovider/providers/aws/aws_routes.go

@@ -90,21 +90,34 @@ func (c *Cloud) ListRoutes(clusterName string) ([]*cloudprovider.Route, error) {
 	}
 
 	for _, r := range table.Routes {
-		instanceID := orEmpty(r.InstanceId)
+		destinationCIDR := aws.StringValue(r.DestinationCidrBlock)
-		destinationCIDR := orEmpty(r.DestinationCidrBlock)
+		if destinationCIDR == "" {
-
-		if instanceID == "" || destinationCIDR == "" {
 			continue
 		}
 
-		instance, found := instances[instanceID]
+		route := &cloudprovider.Route{
-		if !found {
+			Name:            clusterName + "-" + destinationCIDR,
-			glog.Warningf("unable to find instance ID %s in the list of instances being routed to", instanceID)
+			DestinationCIDR: destinationCIDR,
+		}
+
+		// Capture blackhole routes
+		if aws.StringValue(r.State) == ec2.RouteStateBlackhole {
+			route.Blackhole = true
+			routes = append(routes, route)
 			continue
 		}
-		nodeName := mapInstanceToNodeName(instance)
+
-		routeName := clusterName + "-" + destinationCIDR
+		// Capture instance routes
-		routes = append(routes, &cloudprovider.Route{Name: routeName, TargetNode: nodeName, DestinationCIDR: destinationCIDR})
+		instanceID := aws.StringValue(r.InstanceId)
+		if instanceID != "" {
+			instance, found := instances[instanceID]
+			if found {
+				route.TargetNode = mapInstanceToNodeName(instance)
+				routes = append(routes, route)
+			} else {
+				glog.Warningf("unable to find instance ID %s in the list of instances being routed to", instanceID)
+			}
+		}
 	}
 
 	return routes, nil

pkg/controller/route/routecontroller.go

@@ -118,7 +118,9 @@ func (rc *RouteController) reconcile(nodes []*v1.Node, routes []*cloudprovider.R
 	// routeMap maps routeTargetNode->route
 	routeMap := make(map[types.NodeName]*cloudprovider.Route)
 	for _, route := range routes {
-		routeMap[route.TargetNode] = route
+		if route.TargetNode != "" {
+			routeMap[route.TargetNode] = route
+		}
 	}
 
 	wg := sync.WaitGroup{}
@@ -171,8 +173,8 @@ func (rc *RouteController) reconcile(nodes []*v1.Node, routes []*cloudprovider.R
 	}
 	for _, route := range routes {
 		if rc.isResponsibleForRoute(route) {
-			// Check if this route applies to a node we know about & has correct CIDR.
+			// Check if this route is a blackhole, or applies to a node we know about & has an incorrect CIDR.
-			if nodeCIDRs[route.TargetNode] != route.DestinationCIDR {
+			if route.Blackhole || (nodeCIDRs[route.TargetNode] != route.DestinationCIDR) {
 				wg.Add(1)
 				// Delete the route.
 				go func(route *cloudprovider.Route, startTime time.Time) {

pkg/controller/route/routecontroller_test.go

@@ -97,12 +97,12 @@ func TestReconcile(t *testing.T) {
 				&node2,
 			},
 			initialRoutes: []*cloudprovider.Route{
-				{cluster + "-01", "node-1", "10.120.0.0/24"},
+				{cluster + "-01", "node-1", "10.120.0.0/24", false},
-				{cluster + "-02", "node-2", "10.120.1.0/24"},
+				{cluster + "-02", "node-2", "10.120.1.0/24", false},
 			},
 			expectedRoutes: []*cloudprovider.Route{
-				{cluster + "-01", "node-1", "10.120.0.0/24"},
+				{cluster + "-01", "node-1", "10.120.0.0/24", false},
-				{cluster + "-02", "node-2", "10.120.1.0/24"},
+				{cluster + "-02", "node-2", "10.120.1.0/24", false},
 			},
 			expectedNetworkUnavailable: []bool{true, true},
 			clientset:                  fake.NewSimpleClientset(&v1.NodeList{Items: []v1.Node{node1, node2}}),
@@ -114,11 +114,11 @@ func TestReconcile(t *testing.T) {
 				&node2,
 			},
 			initialRoutes: []*cloudprovider.Route{
-				{cluster + "-01", "node-1", "10.120.0.0/24"},
+				{cluster + "-01", "node-1", "10.120.0.0/24", false},
 			},
 			expectedRoutes: []*cloudprovider.Route{
-				{cluster + "-01", "node-1", "10.120.0.0/24"},
+				{cluster + "-01", "node-1", "10.120.0.0/24", false},
-				{cluster + "-02", "node-2", "10.120.1.0/24"},
+				{cluster + "-02", "node-2", "10.120.1.0/24", false},
 			},
 			expectedNetworkUnavailable: []bool{true, true},
 			clientset:                  fake.NewSimpleClientset(&v1.NodeList{Items: []v1.Node{node1, node2}}),
@@ -131,8 +131,8 @@ func TestReconcile(t *testing.T) {
 			},
 			initialRoutes: []*cloudprovider.Route{},
 			expectedRoutes: []*cloudprovider.Route{
-				{cluster + "-01", "node-1", "10.120.0.0/24"},
+				{cluster + "-01", "node-1", "10.120.0.0/24", false},
-				{cluster + "-02", "node-2", "10.120.1.0/24"},
+				{cluster + "-02", "node-2", "10.120.1.0/24", false},
 			},
 			expectedNetworkUnavailable: []bool{true, true},
 			clientset:                  fake.NewSimpleClientset(&v1.NodeList{Items: []v1.Node{node1, node2}}),
@@ -144,14 +144,14 @@ func TestReconcile(t *testing.T) {
 				&node2,
 			},
 			initialRoutes: []*cloudprovider.Route{
-				{cluster + "-01", "node-1", "10.120.0.0/24"},
+				{cluster + "-01", "node-1", "10.120.0.0/24", false},
-				{cluster + "-02", "node-2", "10.120.1.0/24"},
+				{cluster + "-02", "node-2", "10.120.1.0/24", false},
-				{cluster + "-03", "node-3", "10.120.2.0/24"},
+				{cluster + "-03", "node-3", "10.120.2.0/24", false},
-				{cluster + "-04", "node-4", "10.120.3.0/24"},
+				{cluster + "-04", "node-4", "10.120.3.0/24", false},
 			},
 			expectedRoutes: []*cloudprovider.Route{
-				{cluster + "-01", "node-1", "10.120.0.0/24"},
+				{cluster + "-01", "node-1", "10.120.0.0/24", false},
-				{cluster + "-02", "node-2", "10.120.1.0/24"},
+				{cluster + "-02", "node-2", "10.120.1.0/24", false},
 			},
 			expectedNetworkUnavailable: []bool{true, true},
 			clientset:                  fake.NewSimpleClientset(&v1.NodeList{Items: []v1.Node{node1, node2}}),
@@ -163,12 +163,12 @@ func TestReconcile(t *testing.T) {
 				&node2,
 			},
 			initialRoutes: []*cloudprovider.Route{
-				{cluster + "-01", "node-1", "10.120.0.0/24"},
+				{cluster + "-01", "node-1", "10.120.0.0/24", false},
-				{cluster + "-03", "node-3", "10.120.2.0/24"},
+				{cluster + "-03", "node-3", "10.120.2.0/24", false},
 			},
 			expectedRoutes: []*cloudprovider.Route{
-				{cluster + "-01", "node-1", "10.120.0.0/24"},
+				{cluster + "-01", "node-1", "10.120.0.0/24", false},
-				{cluster + "-02", "node-2", "10.120.1.0/24"},
+				{cluster + "-02", "node-2", "10.120.1.0/24", false},
 			},
 			expectedNetworkUnavailable: []bool{true, true},
 			clientset:                  fake.NewSimpleClientset(&v1.NodeList{Items: []v1.Node{node1, node2}}),
@@ -181,11 +181,48 @@ func TestReconcile(t *testing.T) {
 			},
 			initialRoutes: []*cloudprovider.Route{},
 			expectedRoutes: []*cloudprovider.Route{
-				{cluster + "-01", "node-1", "10.120.0.0/24"},
+				{cluster + "-01", "node-1", "10.120.0.0/24", false},
 			},
 			expectedNetworkUnavailable: []bool{true, false},
 			clientset:                  fake.NewSimpleClientset(&v1.NodeList{Items: []v1.Node{node1, nodeNoCidr}}),
 		},
+		// 2 nodes, an extra blackhole route in our range
+		{
+			nodes: []*v1.Node{
+				&node1,
+				&node2,
+			},
+			initialRoutes: []*cloudprovider.Route{
+				{cluster + "-01", "node-1", "10.120.0.0/24", false},
+				{cluster + "-02", "node-2", "10.120.1.0/24", false},
+				{cluster + "-03", "", "10.120.2.0/24", true},
+			},
+			expectedRoutes: []*cloudprovider.Route{
+				{cluster + "-01", "node-1", "10.120.0.0/24", false},
+				{cluster + "-02", "node-2", "10.120.1.0/24", false},
+			},
+			expectedNetworkUnavailable: []bool{true, true},
+			clientset:                  fake.NewSimpleClientset(&v1.NodeList{Items: []v1.Node{node1, node2}}),
+		},
+		// 2 nodes, an extra blackhole route not in our range
+		{
+			nodes: []*v1.Node{
+				&node1,
+				&node2,
+			},
+			initialRoutes: []*cloudprovider.Route{
+				{cluster + "-01", "node-1", "10.120.0.0/24", false},
+				{cluster + "-02", "node-2", "10.120.1.0/24", false},
+				{cluster + "-03", "", "10.1.2.0/24", true},
+			},
+			expectedRoutes: []*cloudprovider.Route{
+				{cluster + "-01", "node-1", "10.120.0.0/24", false},
+				{cluster + "-02", "node-2", "10.120.1.0/24", false},
+				{cluster + "-03", "", "10.1.2.0/24", true},
+			},
+			expectedNetworkUnavailable: []bool{true, true},
+			clientset:                  fake.NewSimpleClientset(&v1.NodeList{Items: []v1.Node{node1, node2}}),
+		},
 	}
 	for i, testCase := range testCases {
 		cloud := &fakecloud.FakeCloud{RouteMap: make(map[string]*fakecloud.FakeRoute)}