e2e/loadbalancer: skip unschedulable nodes during discovery

Skip unsupported or unscheduled worker nodes when discovering candidates for load balancer scenarios.

Some tests, such as hairpin traffic, discover worker nodes using the node-role.kubernetes.io label. If a discovered node has NoSchedule or NoExecute taints, the test fails because the workload is implemented generically and does not define specific tolerations.

Filtering these nodes during discovery ensures the test selects a candidate capable of hosting the workload without requiring changes to the test's pod specification.

Author: mtulio

tests/e2e/loadbalancer.go

@@ -557,6 +557,22 @@ func (e2e *e2eTestConfig) buildDeployment(affinity bool) func(deployment *appsv1
 	}
 }
 
+// isNodeSchedulable checks if a node is schedulable by checking if it has any taints that prevent scheduling pods.
+func (e2e *e2eTestConfig) isNodeSchedulable(node *v1.Node) bool {
+	if node == nil {
+		return false
+	}
+	if len(node.Spec.Taints) == 0 {
+		return true
+	}
+	for _, taint := range node.Spec.Taints {
+		if taint.Effect == v1.TaintEffectNoSchedule || taint.Effect == v1.TaintEffectNoExecute {
+			return false
+		}
+	}
+	return true
+}
+
 // discoverClusterWorkerNode identifies and selects worker nodes in the cluster based on predefined node label selectors.
 // It returns a ClusterNodeDiscovery struct with the discovered information.
 func (e2e *e2eTestConfig) discoverClusterWorkerNode() {
@@ -569,6 +585,10 @@ func (e2e *e2eTestConfig) discoverClusterWorkerNode() {
 		framework.ExpectNoError(err, "failed to list worker nodes")
 		if len(nodeList.Items) > 0 {
 			for _, node := range nodeList.Items {
+				if !isNodeSchedulable {
+					framework.Logf("skipping node %s because it has taints: %v", node.Name, node.Spec.Taints)
+					continue
+				}
 				workerNodeList = append(workerNodeList, node.Name)
 			}
 			// Save the first worker node in the list to be used in cases.