excluding controller node pods by default.

cmd/fetcher/fetcher.go

@@ -8,17 +8,19 @@ import (
 	metav1 "k8s.io/apimachinery/pkg/apis/meta/v1"
 	"k8s.io/client-go/kubernetes"
 	"k8s.io/klog/v2"
+	"os"
 	"regexp"
 	"strings"
 	"time"
 )
 
 type Fetcher struct {
-	KubernetesNamespace string
+	KubernetesNamespace    string
-	SocketPath          string
+	SocketPath             string
-	ContainerdNamespace string
+	ContainerdNamespace    string
-	Nodename            string
+	Nodename               string
-	ReadyDuration       time.Duration
+	ReadyDuration          time.Duration
+	includeControllerNodes bool
 }
 
 func (fetcher *Fetcher) canonicalizeImageName(image string) string {
@@ -72,8 +74,14 @@ func (fetcher *Fetcher) canonicalizeImageName(image string) string {
 	return fullimage
 }
 
-func (fetcher *Fetcher) isReadyForSomeTime(pod *v1.Pod) bool {
+func (fetcher *Fetcher) isReadyForSomeTime(pod *v1.Pod, controllers map[string]bool) bool {
 	ready := false
+	if !fetcher.includeControllerNodes {
+		klog.Infof("Checking %s (%s)", pod.Name, pod.Spec.NodeName)
+		if _, ok := controllers[pod.Spec.NodeName]; ok {
+			return false
+		}
+	}
 	for _, condition := range pod.Status.Conditions {
 		if condition.Type == corev1.PodReady && condition.Status == corev1.ConditionTrue {
 			if time.Now().Sub(condition.LastTransitionTime.Time) > fetcher.ReadyDuration {
@@ -88,6 +96,9 @@ func (fetcher *Fetcher) isReadyForSomeTime(pod *v1.Pod) bool {
 }
 
 func (fetcher *Fetcher) getContainers(clientset *kubernetes.Clientset) map[string]bool {
+
+	controllers := fetcher.getControllerNames(clientset)
+
 	pods, err := clientset.CoreV1().Pods(fetcher.KubernetesNamespace).List(context.Background(),
 		metav1.ListOptions{})
 	if err != nil {
@@ -104,7 +115,7 @@ func (fetcher *Fetcher) getContainers(clientset *kubernetes.Clientset) map[strin
 			if pod.Spec.NodeName == fetcher.Nodename {
 				containersOnCurrentNode[fetcher.canonicalizeImageName(container.Image)] = true
 			} else {
-				if fetcher.isReadyForSomeTime(&pod) {
+				if fetcher.isReadyForSomeTime(&pod, controllers) {
 					containers[fetcher.canonicalizeImageName(container.Image)] = true
 				}
 			}
@@ -114,7 +125,7 @@ func (fetcher *Fetcher) getContainers(clientset *kubernetes.Clientset) map[strin
 			if pod.Spec.NodeName == fetcher.Nodename {
 				containersOnCurrentNode[fetcher.canonicalizeImageName(container.Image)] = true
 			} else {
-				if fetcher.isReadyForSomeTime(&pod) {
+				if fetcher.isReadyForSomeTime(&pod, controllers) {
 					containers[fetcher.canonicalizeImageName(container.Image)] = true
 				}
 			}
@@ -187,6 +198,21 @@ func (fetcher *Fetcher) pullAndPin() error {
 	return nil
 }
 
+func (fetcher *Fetcher) getControllerNames(clientset *kubernetes.Clientset) map[string]bool {
+	nodes, err := clientset.CoreV1().Nodes().List(context.TODO(), metav1.ListOptions{
+		LabelSelector: "node-role.kubernetes.io/control-plane=,!node-role.kubernetes.io/master",
+	})
+	if err != nil {
+		fmt.Printf("Error listing nodes: %v\n", err)
+		os.Exit(1)
+	}
+	nodeset := make(map[string]bool)
+	for _, node := range nodes.Items {
+		nodeset[node.Name] = true
+	}
+	return nodeset
+}
+
 // TODO
 // 1. periodic pull and pin, configurable time interval
 // 2. logging summary results of each pull and pin

cmd/fetcher/main.go

@@ -37,6 +37,8 @@ so they don't get garbage collected'`,
 		"Kubernetes node name the fetcher is running on, it will only fetch images running on other nodes")
 	cmd.PersistentFlags().DurationVar(&fetcher.ReadyDuration, "ready-duration",
 		1*time.Hour, "Time a pod must be ready before its image will be fetched")
+	cmd.PersistentFlags().BoolVar(&fetcher.includeControllerNodes, "include-controllers",
+		false, "Include controller nodes")
 	cmd.Flags().AddGoFlagSet(klogFlags)
 
 	err := cmd.Execute()