Merge pull request #50856 from shyamjvs/save-route-controller-memory

Automatic merge from submit-queue (batch tested with PRs 50303, 50856)

Make route-controller list only relevant routes instead of all of them

Ref https://github.com/kubernetes/kubernetes/issues/50854 (somewhat related issue)

IIUC from the code, route-controller memory is mainly being used in storing routes and nodes (also CIDRs, but that's not much).
This should help reduce that memory usage (particularly when running in a project with large no. of routes), by moving filtering to server-side.
For e.g in kubernetes-scale project we have ~5000 routes (each about 600B) => 3 MB of routes

This doesn't help with reducing time to list the routes as filtering is also linear.

cc @kubernetes/sig-scalability-misc @wojtek-t @gmarek

pkg/cloudprovider/providers/gce/gce_routes.go

@@ -20,7 +20,6 @@ import (
 	"fmt"
 	"net/http"
 	"path"
-	"strings"
 	"time"
 
 	"k8s.io/apimachinery/pkg/types"
@@ -46,7 +45,12 @@ func (gce *GCECloud) ListRoutes(clusterName string) ([]*cloudprovider.Route, err
 		listCall := gce.service.Routes.List(gce.projectID)
 
 		prefix := truncateClusterName(clusterName)
-		listCall = listCall.Filter("name eq " + prefix + "-.*")
+		// Filter for routes starting with clustername AND belonging to the
+		// relevant gcp network AND having description = "k8s-node-route".
+		filter := "(name eq " + prefix + "-.*) "
+		filter = filter + "(network eq " + gce.networkURL + ") "
+		filter = filter + "(description eq " + k8sNodeRouteTag + ")"
+		listCall = listCall.Filter(filter)
 		if pageToken != "" {
 			listCall = listCall.PageToken(pageToken)
 		}
@@ -58,18 +62,6 @@ func (gce *GCECloud) ListRoutes(clusterName string) ([]*cloudprovider.Route, err
 		}
 		pageToken = res.NextPageToken
 		for _, r := range res.Items {
-			if r.Network != gce.networkURL {
-				continue
-			}
-			// Not managed if route description != "k8s-node-route"
-			if r.Description != k8sNodeRouteTag {
-				continue
-			}
-			// Not managed if route name doesn't start with <clusterName>
-			if !strings.HasPrefix(r.Name, prefix) {
-				continue
-			}
-
 			target := path.Base(r.NextHopInstance)
 			// TODO: Should we lastComponent(target) this?
 			targetNodeName := types.NodeName(target) // NodeName == Instance Name on GCE