treat cordoned nodes as failover unavailable

Author: seslly

README.md

@@ -101,9 +101,10 @@ metadata:
     simple-volume.shipstuff.io/failover-grace-period: "1m"
 ```
 
-When no healthy pod using the claim is running on a Ready node for the grace
-period, the controller selects a ready replica node, patches the Deployment's
-`kubernetes.io/hostname` node selector, and deletes stale pods using the claim.
+When no healthy pod using the claim is running on a Ready, schedulable node for
+the grace period, the controller selects a ready replica node, patches the
+Deployment's `kubernetes.io/hostname` node selector, and deletes stale pods
+using the claim.
 
 ## Development
 

internal/controller/failover_controller.go

@@ -183,6 +183,9 @@ func failoverGracePeriod(pvc *corev1.PersistentVolumeClaim) time.Duration {
 func readyNodeSet(nodes []corev1.Node) map[string]bool {
 	out := make(map[string]bool)
 	for _, node := range nodes {
+		if node.Spec.Unschedulable {
+			continue
+		}
 		for _, condition := range node.Status.Conditions {
 			if condition.Type == corev1.NodeReady && condition.Status == corev1.ConditionTrue {
 				out[node.Name] = true

internal/controller/failover_controller_test.go

@@ -71,6 +71,18 @@ func TestFailoverControllerPatchesDeploymentAndDeletesStalePod(t *testing.T) {
 	}
 }
 
+func TestReadyNodeSetExcludesUnschedulableNodes(t *testing.T) {
+	node := readyNode("kapolei-pacific-1", true)
+	node.Spec.Unschedulable = true
+	nodes := readyNodeSet([]corev1.Node{*node, *readyNode("sf-west-1", true)})
+	if nodes["kapolei-pacific-1"] {
+		t.Fatal("unschedulable ready node should be excluded")
+	}
+	if !nodes["sf-west-1"] {
+		t.Fatal("schedulable ready node should be included")
+	}
+}
+
 func deployment(name, namespace, node string) *appsv1.Deployment {
 	return &appsv1.Deployment{
 		ObjectMeta: metav1.ObjectMeta{Name: name, Namespace: namespace},