feat(): switch to informer

cmd/main.go

@@ -2,6 +2,9 @@ package main
 
 import (
 	"fmt"
+	"os"
+	"os/signal"
+	"syscall"
 	"time"
 
 	"git.uploadfilter24.eu/covidnetes/k8s-cilium-node-label/internal/utils"
@@ -32,34 +35,23 @@ func main() {
 		"Caller": "Main",
 	}).Info("Entering main event loop")
 
-	for {
+	stopCh := make(chan struct{})
-		leases, err := internal.GetCiliumL2Leases()
+	go func() {
+		err := internal.StartLeaseInformer(cfg, stopCh)
 		if err != nil {
-			log.WithFields(log.Fields{
+			log.WithFields(log.Fields{"Caller": "Main"}).Fatalf("Lease informer failed: %s", err.Error())
-				"Caller": "Main",
-			}).Errorf("Error getting Cilium L2 leases: %s", err.Error())
 		}
-		for lease := range leases {
+	}()
-			// We should probably group here as there may be multiple leases per node
+
-			node, err := internal.GetNodeNameFromLease(leases[lease])
+	sigCh := make(chan os.Signal, 1)
-			if err != nil {
+	signal.Notify(sigCh, syscall.SIGINT, syscall.SIGTERM)
-				log.WithFields(log.Fields{
+	s := <-sigCh
-					"Caller": "Main",
+	log.WithFields(log.Fields{
-				}).Errorf("Error getting node name from Cilium L2 lease: %s", err.Error())
+		"Caller": "Main",
-			}
+		"Signal": s.String(),
-			if cfg.DryRun {
+	}).Info("Signal received, shutting down")
-				log.WithFields(log.Fields{
+
-					"Caller": "Main",
+	close(stopCh)
-				}).Info(fmt.Sprintf("Dry run enabled, would label node %s with %s=true", node, cfg.CiliumLabel))
+
-			} else {
+	time.Sleep(2 * time.Second)
-				err := internal.LabelNode(node, leases[lease].Name, cfg)
-				if err != nil {
-					log.WithFields(log.Fields{
-						"Caller": "Main",
-					}).Error(fmt.Sprintf("Error labeling node: %s", err.Error()))
-				}
-			}
-		}
-		time.Sleep(5 * time.Minute)
-	}
 }

go.mod

@@ -21,6 +21,7 @@ require (
 	github.com/go-openapi/jsonreference v0.20.2 // indirect
 	github.com/go-openapi/swag v0.23.0 // indirect
 	github.com/google/gnostic-models v0.7.0 // indirect
+	github.com/google/go-cmp v0.7.0 // indirect
 	github.com/google/uuid v1.6.0 // indirect
 	github.com/josharian/intern v1.0.0 // indirect
 	github.com/json-iterator/go v1.1.12 // indirect
@@ -28,6 +29,7 @@ require (
 	github.com/modern-go/concurrent v0.0.0-20180306012644-bacd9c7ef1dd // indirect
 	github.com/modern-go/reflect2 v1.0.3-0.20250322232337-35a7c28c31ee // indirect
 	github.com/munnerz/goautoneg v0.0.0-20191010083416-a7dc8b61c822 // indirect
+	github.com/pmezard/go-difflib v1.0.0 // indirect
 	github.com/x448/float16 v0.8.4 // indirect
 	go.yaml.in/yaml/v2 v2.4.3 // indirect
 	go.yaml.in/yaml/v3 v3.0.4 // indirect

go.sum

@@ -81,6 +81,8 @@ github.com/stretchr/testify v1.11.1 h1:7s2iGBzp5EwR7/aIZr8ao5+dra3wiQyKjjFuvgVKu
 github.com/stretchr/testify v1.11.1/go.mod h1:wZwfW3scLgRK+23gO65QZefKpKQRnfz6sD981Nm4B6U=
 github.com/x448/float16 v0.8.4 h1:qLwI1I70+NjRFUR3zs1JPUCgaCXSh3SW62uAKT1mSBM=
 github.com/x448/float16 v0.8.4/go.mod h1:14CWIYCyZA/cWjXOioeEpHeN/83MdbZDRQHoFcYsOfg=
+go.uber.org/goleak v1.3.0 h1:2K3zAYmnTNqV73imy9J1T3WC+gmCePx2hEGkimedGto=
+go.uber.org/goleak v1.3.0/go.mod h1:CoHD4mav9JJNrW/WLlf7HGZPjdw8EucARQHekz1X6bE=
 go.yaml.in/yaml/v2 v2.4.3 h1:6gvOSjQoTB3vt1l+CU+tSyi/HOjfOjRLJ4YwYZGwRO0=
 go.yaml.in/yaml/v2 v2.4.3/go.mod h1:zSxWcmIDjOzPXpjlTTbAsKokqkDNAVtZO0WOMiT90s8=
 go.yaml.in/yaml/v3 v3.0.4 h1:tfq32ie2Jv2UxXFdLJdh3jXuOzWiL1fo0bu/FbuKpbc=

internal/informer.go

@@ -0,0 +1,97 @@
+package internal
+
+import (
+	"fmt"
+	"strings"
+	"time"
+
+	log "github.com/sirupsen/logrus"
+	v1 "k8s.io/api/coordination/v1"
+	"k8s.io/client-go/informers"
+	"k8s.io/client-go/tools/cache"
+)
+
+// StartLeaseInformer starts a long-running informer watching Lease objects in the kube-system namespace.
+// It will react to Add/Update events for leases whose name starts with "cilium-l2announce" and label
+// the corresponding node.
+func StartLeaseInformer(cfg *Config, stopCh <-chan struct{}) error {
+	log.WithFields(log.Fields{"Caller": "StartLeaseInformer"}).Info("Starting lease informer")
+
+	client, err := generateClient()
+	if err != nil {
+		return fmt.Errorf("Could not generate client for informer: %s", err.Error())
+	}
+
+	factory := informers.NewSharedInformerFactoryWithOptions(&client, 0, informers.WithNamespace("kube-system"))
+	leaseInformer := factory.Coordination().V1().Leases().Informer()
+
+	leaseInformer.AddEventHandler(cache.ResourceEventHandlerFuncs{
+		AddFunc: func(obj interface{}) {
+			handleLease(obj, cfg)
+		},
+		UpdateFunc: func(oldObj, newObj interface{}) {
+			handleLease(newObj, cfg)
+		},
+		DeleteFunc: func(obj interface{}) {
+			// nothing to do on delete for now
+		},
+	})
+
+	factory.Start(stopCh)
+
+	// wait for cache sync with timeout
+	synced := make(chan struct{})
+	go func() {
+		if !cache.WaitForCacheSync(stopCh, leaseInformer.HasSynced) {
+			close(synced)
+			return
+		}
+		close(synced)
+	}()
+
+	select {
+	case <-synced:
+		// proceed
+	case <-time.After(15 * time.Second):
+		return fmt.Errorf("timed out waiting for informer cache sync")
+	}
+
+	log.WithFields(log.Fields{"Caller": "StartLeaseInformer"}).Info("Lease informer running")
+	return nil
+}
+
+func handleLease(obj interface{}, cfg *Config) {
+	lease, ok := obj.(*v1.Lease)
+	if !ok {
+		log.WithFields(log.Fields{"Caller": "handleLease"}).Warn("Could not cast object to Lease")
+		return
+	}
+
+	if lease == nil {
+		return
+	}
+
+	if lease.Name == "" || len(lease.Name) < 1 {
+		return
+	}
+
+	if !strings.HasPrefix(lease.Name, "cilium-l2announce") {
+		return
+	}
+
+	node, err := GetNodeNameFromLease(*lease)
+	if err != nil {
+		log.WithFields(log.Fields{"Caller": "handleLease", "Lease": lease.Name}).Errorf("Error parsing lease: %s", err.Error())
+		return
+	}
+
+	if cfg.DryRun {
+		log.WithFields(log.Fields{"Caller": "handleLease"}).Infof("Dry run: would label node %s with %s=true (lease %s)", node, cfg.CiliumLabel, lease.Name)
+		return
+	}
+
+	err = LabelNode(node, lease.Name, cfg)
+	if err != nil {
+		log.WithFields(log.Fields{"Caller": "handleLease", "Node": node, "Lease": lease.Name}).Errorf("Error labeling node: %s", err.Error())
+	}
+}

internal/kube.go

@@ -92,36 +92,36 @@ func RemoveLabelFromNode(nodeName string) error {
 	return nil
 }
 
-func GetCiliumL2Leases() ([]v1.Lease, error) {
+// func GetCiliumL2Leases() ([]v1.Lease, error) {
-	client, err := generateClient()
+// 	client, err := generateClient()
-	if err != nil {
+// 	if err != nil {
-		log.WithFields(log.Fields{"Caller": "GetCiliumL2Leases"}).Errorf("Could not generate client: %s", err.Error())
+// 		log.WithFields(log.Fields{"Caller": "GetCiliumL2Leases"}).Errorf("Could not generate client: %s", err.Error())
-		return nil, err
+// 		return nil, err
-	}
+// 	}
 
-	leases, err := client.CoordinationV1().Leases("kube-system").List(context.TODO(), metav1.ListOptions{})
+// 	leases, err := client.CoordinationV1().Leases("kube-system").List(context.TODO(), metav1.ListOptions{})
-	if err != nil {
+// 	if err != nil {
-		log.WithFields(log.Fields{"Caller": "GetCiliumL2Leases"}).Errorf("Could not list leases: %s", err.Error())
+// 		log.WithFields(log.Fields{"Caller": "GetCiliumL2Leases"}).Errorf("Could not list leases: %s", err.Error())
-		return nil, err
+// 		return nil, err
-	}
+// 	}
 
-	ciliumLeases := []v1.Lease{}
+// 	ciliumLeases := []v1.Lease{}
 
-	for _, l := range leases.Items {
+// 	for _, l := range leases.Items {
-		if strings.HasPrefix(l.Name, "cilium-l2announce") {
+// 		if strings.HasPrefix(l.Name, "cilium-l2announce") {
-			log.WithFields(log.Fields{
+// 			log.WithFields(log.Fields{
-				"Caller": "GetCiliumL2Leases",
+// 				"Caller": "GetCiliumL2Leases",
-				"Lease":  l.Name,
+// 				"Lease":  l.Name,
-			}).Info("Found Cilium L2 lease")
+// 			}).Info("Found Cilium L2 lease")
-			// Pretty-print a couple of fields for debugging
+// 			// Pretty-print a couple of fields for debugging
-			if l.Spec.HolderIdentity != nil {
+// 			if l.Spec.HolderIdentity != nil {
-				log.WithFields(log.Fields{"HolderIdentity": *l.Spec.HolderIdentity}).Debug("HolderIdentity")
+// 				log.WithFields(log.Fields{"HolderIdentity": *l.Spec.HolderIdentity}).Debug("HolderIdentity")
-			}
+// 			}
-			ciliumLeases = append(ciliumLeases, l)
+// 			ciliumLeases = append(ciliumLeases, l)
-		}
+// 		}
-	}
+// 	}
-	return ciliumLeases, nil
+// 	return ciliumLeases, nil
-}
+// }
 
 func GetNodeNameFromLease(lease v1.Lease) (string, error) {
 	if lease.Spec.HolderIdentity == nil {