fix/optimize the logic of finding cluster service/pod ip range

pkg/discovery/network/generic.go

@@ -24,7 +24,6 @@ import (
 	"os"
 	"regexp"
 
-	"github.com/pkg/errors"
 	"github.com/submariner-io/submariner/pkg/cni"
 	corev1 "k8s.io/api/core/v1"
 	v1meta "k8s.io/apimachinery/pkg/apis/meta/v1"
@@ -78,22 +77,31 @@ func discoverNetwork(ctx context.Context, client controllerClient.Client) (*Clus
 
 func findClusterIPRange(ctx context.Context, client controllerClient.Client) (string, error) {
 	clusterIPRange, err := findClusterIPRangeFromApiserver(ctx, client)
-	if err != nil || clusterIPRange != "" {
-		return clusterIPRange, err
+	if clusterIPRange != "" {
+		return clusterIPRange, nil
+	}
+
+	clusterIPRange, err = findClusterIPRangeFromKubeController(ctx, client)
+	if clusterIPRange != "" {
+		return clusterIPRange, nil
 	}
 
 	clusterIPRange, err = findClusterIPRangeFromServiceCreation(ctx, client)
-	if err != nil || clusterIPRange != "" {
-		return clusterIPRange, err
+	if clusterIPRange != "" {
+		return clusterIPRange, nil
 	}
 
-	return "", nil
+	return "", err
 }
 
 func findClusterIPRangeFromApiserver(ctx context.Context, client controllerClient.Client) (string, error) {
 	return FindPodCommandParameter(ctx, client, "component=kube-apiserver", "--service-cluster-ip-range")
 }
 
+func findClusterIPRangeFromKubeController(ctx context.Context, client controllerClient.Client) (string, error) {
+	return FindPodCommandParameter(ctx, client, "component=kube-controller-manager", "--service-cluster-ip-range")
+}
+
 func findClusterIPRangeFromServiceCreation(ctx context.Context, client controllerClient.Client) (string, error) {
 	ns := os.Getenv("WATCH_NAMESPACE")
 	// WATCH_NAMESPACE env should be set to operator's namespace, if running in operator
@@ -153,50 +161,23 @@ func parseServiceCIDRFrom(msg string) (string, error) {
 }
 
 func findPodIPRange(ctx context.Context, client controllerClient.Client) (string, error) {
-	podIPRange, err := findPodIPRangeKubeController(ctx, client)
-	if err != nil || podIPRange != "" {
-		return podIPRange, err
-	}
-
-	podIPRange, err = findPodIPRangeKubeProxy(ctx, client)
-	if err != nil || podIPRange != "" {
-		return podIPRange, err
+	podIPRange, err := findPodIPRangeFromKubeController(ctx, client)
+	if podIPRange != "" {
+		return podIPRange, nil
 	}
 
-	podIPRange, err = findPodIPRangeFromNodeSpec(ctx, client)
-	if err != nil || podIPRange != "" {
-		return podIPRange, err
+	podIPRange, err = findPodIPRangeFromKubeProxy(ctx, client)
+	if podIPRange != "" {
+		return podIPRange, nil
 	}
 
-	return "", nil
+	return "", err
 }
 
-func findPodIPRangeKubeController(ctx context.Context, client controllerClient.Client) (string, error) {
+func findPodIPRangeFromKubeController(ctx context.Context, client controllerClient.Client) (string, error) {
 	return FindPodCommandParameter(ctx, client, "component=kube-controller-manager", "--cluster-cidr")
 }
 
-func findPodIPRangeKubeProxy(ctx context.Context, client controllerClient.Client) (string, error) {
-	return FindPodCommandParameter(ctx, client, "component=kube-proxy", "--cluster-cidr")
-}
-
-func findPodIPRangeFromNodeSpec(ctx context.Context, client controllerClient.Client) (string, error) {
-	nodes := &corev1.NodeList{}
-
-	err := client.List(ctx, nodes)
-	if err != nil {
-		return "", errors.WithMessagef(err, "error listing nodes")
-	}
-
-	return parseToPodCidr(nodes.Items)
-}
-
-func parseToPodCidr(nodes []corev1.Node) (string, error) {
-	// In K8s, each node is typically assigned a unique PodCIDR range for the pods that run on that node.
-	// Each node's PodCIDR is used to allocate IP addresses to the pods scheduled on that node. Only if
-	// the cluster is a single node deployment, we should rely on the node.Spec.PodCIDR as podCIDR of the cluster.
-	if len(nodes) == 1 {
-		return nodes[0].Spec.PodCIDR, nil
-	}
-
-	return "", nil
+func findPodIPRangeFromKubeProxy(ctx context.Context, client controllerClient.Client) (string, error) {
+	return FindPodCommandParameter(ctx, client, "k8s-app=kube-proxy", "--cluster-cidr")
 }