factory: strip Managed Fields to reduce memory usage

We don't care about them, so why cache them and use a ton
of memory.

Inspired by kubernetes/kubernetes#118455

Signed-off-by: Dan Williams <dcbw@redhat.com>

go-controller/pkg/factory/factory.go

@@ -2,6 +2,7 @@ package factory
 
 import (
 	"context"
+	"encoding/json"
 	"fmt"
 	"reflect"
 	"sync/atomic"
@@ -57,6 +58,7 @@ import (
 	kapi "k8s.io/api/core/v1"
 	discovery "k8s.io/api/discovery/v1"
 	knet "k8s.io/api/networking/v1"
+	"k8s.io/apimachinery/pkg/api/meta"
 	metav1 "k8s.io/apimachinery/pkg/apis/meta/v1"
 	"k8s.io/apimachinery/pkg/fields"
 	"k8s.io/apimachinery/pkg/labels"
@@ -193,14 +195,37 @@ func NewMasterWatchFactory(ovnClientset *util.OVNMasterClientset) (*WatchFactory
 
 // NewOVNKubeControllerWatchFactory initializes a new watch factory for the ovnkube controller process
 func NewOVNKubeControllerWatchFactory(ovnClientset *util.OVNKubeControllerClientset) (*WatchFactory, error) {
+	// Informer transform to trim ManagedFields for memory efficiency.
+	trim := func(obj interface{}) (interface{}, error) {
+		if accessor, err := meta.Accessor(obj); err == nil {
+			accessor.SetManagedFields(nil)
+		}
+		if pod, ok := obj.(*kapi.Pod); ok {
+			pod.Spec.Volumes = []kapi.Volume{}
+			for i := range pod.Spec.Containers {
+				pod.Spec.Containers[i].Command = nil
+				pod.Spec.Containers[i].Args = nil
+				pod.Spec.Containers[i].Env = nil
+				pod.Spec.Containers[i].VolumeMounts = nil
+			}
+		} else if node, ok := obj.(*kapi.Node); ok {
+			node.Status.Images = nil
+			node.Status.VolumesInUse = nil
+			node.Status.VolumesAttached = nil
+			node.Status.Capacity = nil
+			node.Status.Allocatable = nil
+		}
+		return obj, nil
+	}
+
 	// resync time is 12 hours, none of the resources being watched in ovn-kubernetes have
 	// any race condition where a resync may be required e.g. cni executable on node watching for
 	// events on pods and assuming that an 'ADD' event will contain the annotations put in by
 	// ovnkube master (currently, it is just a 'get' loop)
 	// the downside of making it tight (like 10 minutes) is needless spinning on all resources
 	// However, AddEventHandlerWithResyncPeriod can specify a per handler resync period
 	wf := &WatchFactory{
-		iFactory:             informerfactory.NewSharedInformerFactory(ovnClientset.KubeClient, resyncInterval),
+		iFactory:             informerfactory.NewSharedInformerFactoryWithOptions(ovnClientset.KubeClient, resyncInterval, informerfactory.WithTransform(trim)),
 		anpFactory:           anpinformerfactory.NewSharedInformerFactory(ovnClientset.ANPClient, resyncInterval),
 		eipFactory:           egressipinformerfactory.NewSharedInformerFactory(ovnClientset.EgressIPClient, resyncInterval),
 		efFactory:            egressfirewallinformerfactory.NewSharedInformerFactory(ovnClientset.EgressFirewallClient, resyncInterval),