periodically checking now for pods.

Now also dealing with deleted resources in the time interval.
Making sure that new pods are not immediately synced on other nodes to avoid pull rate limits caused by this code.

cmd/fetcher/config.go

@@ -3,10 +3,12 @@ package main
 import "time"
 
 type Config struct {
+	PollInterval           time.Duration
 	KubernetesNamespace    string
 	SocketPath             string
 	ContainerdNamespace    string
 	Nodename               string
 	ReadyDuration          time.Duration
 	includeControllerNodes bool
+	monitoringWindowSize   time.Duration
 }

cmd/fetcher/fetcher.go

@@ -3,7 +3,6 @@ package main
 import (
 	"context"
 	"fmt"
-	corev1 "k8s.io/api/core/v1"
 	v1 "k8s.io/api/core/v1"
 	metav1 "k8s.io/apimachinery/pkg/apis/meta/v1"
 	"k8s.io/client-go/kubernetes"
@@ -15,14 +14,16 @@ import (
 )
 
 type Fetcher struct {
-	config    *Config
 	clientset *kubernetes.Clientset
+	config    *Config
+	watcher   *Watcher
 }
 
-func NewFetcher(config *Config, clientset *kubernetes.Clientset) *Fetcher {
+func NewFetcher(clientset *kubernetes.Clientset, config *Config, watcher *Watcher) *Fetcher {
 	return &Fetcher{
 		config:    config,
 		clientset: clientset,
+		watcher:   watcher,
 	}
 }
 
@@ -77,48 +78,39 @@ func (fetcher *Fetcher) canonicalizeImageName(image string) string {
 	return fullimage
 }
 
-func (fetcher *Fetcher) isReadyForSomeTime(pod *v1.Pod, controllers map[string]bool) bool {
+func (fetcher *Fetcher) wasReady(pod *v1.Pod, controllers map[string]bool) bool {
-	ready := false
 	if !fetcher.config.includeControllerNodes {
-		klog.Infof("Checking %s (%s)", pod.Name, pod.Spec.NodeName)
+		klog.V(3).Infof("Checking %s (%s)", pod.Name, pod.Spec.NodeName)
 		if _, ok := controllers[pod.Spec.NodeName]; ok {
 			return false
 		}
 	}
-	for _, condition := range pod.Status.Conditions {
+	return time.Now().Sub(pod.CreationTimestamp.Time) >= fetcher.config.ReadyDuration
-		if condition.Type == corev1.PodReady && condition.Status == corev1.ConditionTrue {
-			if time.Now().Sub(condition.LastTransitionTime.Time) > fetcher.config.ReadyDuration {
-				ready = true
-			}
-		}
-	}
-	if pod.DeletionTimestamp != nil {
-		ready = false
-	}
-	return ready
 }
 
 func (fetcher *Fetcher) getContainers(clientset *kubernetes.Clientset) map[string]bool {
 
 	controllers := fetcher.getControllerNames(clientset)
 
-	pods, err := clientset.CoreV1().Pods(fetcher.config.KubernetesNamespace).List(context.Background(),
+	pods := fetcher.watcher.getPods()
-		metav1.ListOptions{})
+
-	if err != nil {
+	//pods, err := clientset.CoreV1().Pods(fetcher.config.KubernetesNamespace).List(context.Background(),
-		panic(err)
+	//	metav1.ListOptions{})
-	}
+	//if err != nil {
+	//	panic(err)
+	//}
 
 	containers := make(map[string]bool)
 	containersOnCurrentNode := make(map[string]bool)
 
-	for _, pod := range pods.Items {
+	for _, pod := range pods {
 		klog.V(3).Infof("%s/%s\n", pod.Namespace, pod.Name)
 		for _, container := range pod.Spec.InitContainers {
 			klog.V(3).Infof("  %s\n", container.Image)
 			if pod.Spec.NodeName == fetcher.config.Nodename {
 				containersOnCurrentNode[fetcher.canonicalizeImageName(container.Image)] = true
 			} else {
-				if fetcher.isReadyForSomeTime(&pod, controllers) {
+				if fetcher.wasReady(pod, controllers) {
 					containers[fetcher.canonicalizeImageName(container.Image)] = true
 				}
 			}
@@ -128,7 +120,7 @@ func (fetcher *Fetcher) getContainers(clientset *kubernetes.Clientset) map[strin
 			if pod.Spec.NodeName == fetcher.config.Nodename {
 				containersOnCurrentNode[fetcher.canonicalizeImageName(container.Image)] = true
 			} else {
-				if fetcher.isReadyForSomeTime(&pod, controllers) {
+				if fetcher.wasReady(pod, controllers) {
 					containers[fetcher.canonicalizeImageName(container.Image)] = true
 				}
 			}

cmd/fetcher/main.go

@@ -14,7 +14,6 @@ func main() {
 
 	clientset := GetKubernetesConnection()
 	config := &Config{}
-	fetcher := NewFetcher(config, clientset)
 
 	cmd := &cobra.Command{
 		Use:   "kube-fetcher",
@@ -24,11 +23,25 @@ Queries k8s for all running pods and makes sure that all
 images referenced in pods are made available on the local k8s node and pinned
 so they don't get garbage collected'`,
 		RunE: func(cmd *cobra.Command, args []string) error {
-			err := fetcher.pullAndPin()
+			serializer := make(chan func())
-			//watcher := Watcher{}
+			go func() {
-			//watcher.WatchPods(clientset, config.KubernetesNamespace)
+				for action := range serializer {
+					action()
+				}
+			}()
+			watcher := NewWatcher(clientset, config.monitoringWindowSize, config.KubernetesNamespace, serializer)
+			fetcher := NewFetcher(clientset, config, watcher)
 
-			return err
+			ticker := time.NewTicker(config.PollInterval)
+			for {
+				select {
+				case <-ticker.C:
+					serializer <- func() {
+						klog.V(3).Infof("Fetcher.pullAndPin")
+						fetcher.pullAndPin()
+					}
+				}
+			}
 		},
 	}
 
@@ -44,6 +57,10 @@ so they don't get garbage collected'`,
 		1*time.Hour, "Time a pod must be ready before its image will be fetched")
 	cmd.PersistentFlags().BoolVar(&config.includeControllerNodes, "include-controllers",
 		false, "Include controller nodes")
+	cmd.PersistentFlags().DurationVar(&config.monitoringWindowSize, "monitoring-window",
+		6*time.Hour, "Monitoring window to see what pods were active")
+	cmd.PersistentFlags().DurationVar(&config.PollInterval, "poll-interval",
+		1*time.Minute, "Poll interval for checking whether to pull images. ")
 	cmd.Flags().AddGoFlagSet(klogFlags)
 
 	err := cmd.Execute()

cmd/fetcher/watcher.go

@@ -1,17 +1,55 @@
 package main
 
 import (
+	"fmt"
 	corev1 "k8s.io/api/core/v1"
 	"k8s.io/apimachinery/pkg/fields"
+	"k8s.io/apimachinery/pkg/types"
 	"k8s.io/client-go/kubernetes"
 	"k8s.io/client-go/tools/cache"
 	"k8s.io/klog/v2"
+	"time"
 )
 
 type Watcher struct {
+	monitoringWindow time.Duration
+	// Pods that were active in the given window. This list is pruned
+	// for entries that have not been running for some time.
+	// Map of Pod.metadata.uid to pod
+	pods       map[types.UID]*corev1.Pod
+	serializer chan<- func()
 }
 
-func (watcher *Watcher) WatchPods(
+func NewWatcher(clientset *kubernetes.Clientset, monitoringWindow time.Duration, namespace string, serializer chan<- func()) *Watcher {
+	watcher := &Watcher{
+		monitoringWindow: monitoringWindow,
+		pods:             make(map[types.UID]*corev1.Pod),
+		serializer:       serializer,
+	}
+	watcher.watchPods(clientset, namespace)
+	return watcher
+}
+
+func (watcher *Watcher) getPods() []*corev1.Pod {
+	pods := make(map[types.UID]*corev1.Pod)
+	klog.V(3).Infof("PODS %v", pods)
+	res := make([]*corev1.Pod, 0)
+	for uid, pod := range watcher.pods {
+		klog.V(3).Infof("Checking pod %s/%s\n", pod.Namespace, pod.Name)
+		if pod.DeletionTimestamp == nil ||
+			pod.DeletionTimestamp.IsZero() ||
+			time.Now().Sub(pod.DeletionTimestamp.Time) <= watcher.monitoringWindow {
+			klog.V(3).Infof("Pod found in moving windows %s/%s\n",
+				pod.Namespace, pod.Name)
+			pods[uid] = pod
+			res = append(res, pod)
+		}
+	}
+	watcher.pods = pods
+	return res
+}
+
+func (watcher *Watcher) watchPods(
 	clientset *kubernetes.Clientset,
 	namespace string) {
 
@@ -23,8 +61,17 @@ func (watcher *Watcher) WatchPods(
 	)
 
 	addOrUpdate := func(obj interface{}) {
-		pod := watcher.getPod(obj)
+		watcher.serializer <- func() {
-		klog.Infof("Added/updated %s/%s\n", pod.Namespace, pod.Name)
+			pod := watcher.getPod(obj)
+			// only add the pod if it all its containers were ready
+			for _, condition := range pod.Status.Conditions {
+				if condition.Type == corev1.PodReady && condition.Status != corev1.ConditionTrue {
+					return
+				}
+			}
+			klog.V(3).Infof("Added/updated %s/%s\n", pod.Namespace, pod.Name)
+			watcher.pods[pod.UID] = pod
+		}
 	}
 
 	options := cache.InformerOptions{
@@ -36,8 +83,11 @@ func (watcher *Watcher) WatchPods(
 				addOrUpdate(obj)
 			},
 			DeleteFunc: func(obj any) {
-				pod := watcher.getPod(obj)
+				watcher.serializer <- func() {
-				klog.Infof("Delete %s/%s\n", pod.Namespace, pod.Name)
+					pod := watcher.getPod(obj)
+					klog.V(3).Infof("Delete %s/%s\n", pod.Namespace, pod.Name)
+					watcher.pods[pod.UID].DeletionTimestamp.Time = time.Now()
+				}
 			},
 		},
 		ResyncPeriod: 0,
@@ -47,7 +97,10 @@ func (watcher *Watcher) WatchPods(
 	stop := make(chan struct{})
 	defer close(stop)
 	go controller.Run(stop)
-	select {}
+	// Wait for the cache to sync
+	if !cache.WaitForCacheSync(stop, controller.HasSynced) {
+		panic(fmt.Errorf("failed to sync cache"))
+	}
 }
 
 func (watcher *Watcher) getPod(obj any) *corev1.Pod {