Enhance flannel discovery by listing DaemonSets across all namespaces

Signed-off-by: Aswin A <[email protected]>

Contributes to:  submariner-io/submariner#3210

pkg/discovery/network/canal.go

@@ -43,8 +43,12 @@ func discoverCanalFlannelNetwork(ctx context.Context, client controllerClient.Cl
 		return nil, nil
 	}
 
+	// Get the namespace from the first DaemonSet
+	namespace := daemonsets.Items[0].Namespace
+
+	// Pass the namespace to the function call
 	clusterNetwork, err := extractCIDRsFromFlannelConfigMap(ctx, client, findFlannelConfigMapName(
-		daemonsets.Items[0].Spec.Template.Spec.Volumes))
+		daemonsets.Items[0].Spec.Template.Spec.Volumes), namespace)
 	if err != nil || clusterNetwork == nil {
 		return nil, err
 	}
@@ -53,3 +57,4 @@ func discoverCanalFlannelNetwork(ctx context.Context, client controllerClient.Cl
 
 	return clusterNetwork, nil
 }
+

pkg/discovery/network/flannel.go

@@ -28,65 +28,68 @@ import (
 	appsv1 "k8s.io/api/apps/v1"
 	corev1 "k8s.io/api/core/v1"
 	apierrors "k8s.io/apimachinery/pkg/api/errors"
-	metav1 "k8s.io/apimachinery/pkg/apis/meta/v1"
 	controllerClient "sigs.k8s.io/controller-runtime/pkg/client"
 )
 
 //nolint:nilnil // Intentional as the purpose is to discover.
 func discoverFlannelNetwork(ctx context.Context, client controllerClient.Client) (*ClusterNetwork, error) {
 	daemonsets := &appsv1.DaemonSetList{}
 
-	err := client.List(ctx, daemonsets, controllerClient.InNamespace(metav1.NamespaceSystem))
+	// Use a label selector to find DaemonSets with the "k8s-app=flannel" label in any namespace
+	labelSelector := controllerClient.MatchingLabels{"k8s-app": "flannel"}
+	err := client.List(ctx, daemonsets, labelSelector)
 	if err != nil {
 		return nil, errors.WithMessage(err, "error listing the Daemonsets for flannel discovery")
 	}
 
+	var flannelDaemonSet *appsv1.DaemonSet
 	volumes := make([]corev1.Volume, 0)
+
 	// look for a daemonset matching "flannel"
-	for k := range daemonsets.Items {
-		if strings.Contains(daemonsets.Items[k].Name, "flannel") {
-			volumes = daemonsets.Items[k].Spec.Template.Spec.Volumes
+	for _, ds := range daemonsets.Items {
+		if strings.Contains(ds.Name, "flannel") {
+			flannelDaemonSet = &ds
+			volumes = ds.Spec.Template.Spec.Volumes
+			break
 		}
 	}
 
-	if len(volumes) < 1 {
+	if flannelDaemonSet == nil || len(volumes) < 1 {
 		return nil, nil
 	}
 
-	clusterNetwork, err := extractCIDRsFromFlannelConfigMap(ctx, client, findFlannelConfigMapName(volumes))
+	// Extract the ConfigMap name from the DaemonSet's volumes and check in the same namespace
+	configMapName := findFlannelConfigMapName(volumes)
+	clusterNetwork, err := extractCIDRsFromFlannelConfigMap(ctx, client, configMapName, flannelDaemonSet.Namespace)
 	if err != nil || clusterNetwork == nil {
 		return nil, err
 	}
 
 	clusterNetwork.NetworkPlugin = cni.Flannel
-
 	return clusterNetwork, nil
 }
 
 //nolint:nilnil // Intentional as the purpose is to discover.
-func extractCIDRsFromFlannelConfigMap(ctx context.Context, client controllerClient.Client, configMapName string) (*ClusterNetwork, error) {
+func extractCIDRsFromFlannelConfigMap(ctx context.Context, client controllerClient.Client, configMapName, namespace string) (*ClusterNetwork, error) {
 	var podCIDR *string
 
 	if configMapName == "" {
 		podIPRange, err := findPodIPRange(ctx, client)
 		if err != nil {
 			return nil, err
 		}
-
 		podCIDR = &podIPRange
 	} else {
-		// look for the configmap details using the configmap name discovered from the daemonset
+		// Look for the ConfigMap in the specified namespace
 		cm := &corev1.ConfigMap{}
-
 		err := client.Get(ctx, controllerClient.ObjectKey{
-			Namespace: metav1.NamespaceSystem,
+			Namespace: namespace,
 			Name:      configMapName,
 		}, cm)
 		if err != nil {
 			if apierrors.IsNotFound(err) {
 				return nil, nil
 			}
-
 			return nil, errors.WithMessagef(err, "error retrieving the flannel ConfigMap %q", configMapName)
 		}
 

pkg/discovery/network/flannel_test.go

@@ -63,10 +63,13 @@ var flannelDaemonSet = appsv1.DaemonSet{
 	ObjectMeta: metav1.ObjectMeta{
 		Name:      "kube-flannel-ds",
 		Namespace: metav1.NamespaceSystem,
+		Labels:    map[string]string{"k8s-app": "flannel"},
 	},
 	Spec: appsv1.DaemonSetSpec{
 		Template: corev1.PodTemplateSpec{
-			ObjectMeta: metav1.ObjectMeta{},
+			ObjectMeta: metav1.ObjectMeta{
+				Labels: map[string]string{"k8s-app": "flannel"},
+			},
 			Spec: corev1.PodSpec{
 				Volumes: []corev1.Volume{flannelCfgVolume},
 			},