fix: clear stale FailedNodes entry when a node recovers

internal/controller/node_controller.go

@@ -159,6 +159,8 @@ func (r *RuleReadinessController) processNodeAgainstAllRules(ctx context.Context
 			r.recordNodeFailure(rule, node.Name, "EvaluationError", err.Error())
 			errs = append(errs, err)
 			metrics.Failures.WithLabelValues(rule.Name, "EvaluationError").Inc()
+		} else {
+			r.clearNodeFailure(rule, node.Name)
 		}
 
 		// Persist the rule status
@@ -425,6 +427,17 @@ func (r *RuleReadinessController) recordNodeFailure(
 	rule.Status.FailedNodes = failedNodes
 }
 
+// clearNodeFailure removes any failure record for a specific node from the rule status.
+func (r *RuleReadinessController) clearNodeFailure(rule *readinessv1alpha1.NodeReadinessRule, nodeName string) {
+	var failedNodes []readinessv1alpha1.NodeFailure
+	for _, failure := range rule.Status.FailedNodes {
+		if failure.NodeName != nodeName {
+			failedNodes = append(failedNodes, failure)
+		}
+	}
+	rule.Status.FailedNodes = failedNodes
+}
+
 // SyncNodeStateMetrics synchronizes the NodesByState Prometheus metrics with the current rule status.
 func (r *RuleReadinessController) SyncNodeStateMetrics(ctx context.Context, rule *readinessv1alpha1.NodeReadinessRule) {
 	var ready, notReady, bootstrapping float64

internal/controller/node_controller_unit_test.go

@@ -0,0 +1,62 @@
+/*
+Copyright The Kubernetes Authors.
+
+Licensed under the Apache License, Version 2.0 (the "License");
+you may not use this file except in compliance with the License.
+You may obtain a copy of the License at
+
+    http://www.apache.org/licenses/LICENSE-2.0
+
+Unless required by applicable law or agreed to in writing, software
+distributed under the License is distributed on an "AS IS" BASIS,
+WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+See the License for the specific language governing permissions and
+limitations under the License.
+*/
+
+package controller
+
+import (
+	"testing"
+
+	. "github.com/onsi/gomega"
+	metav1 "k8s.io/apimachinery/pkg/apis/meta/v1"
+
+	readinessv1alpha1 "sigs.k8s.io/node-readiness-controller/api/v1alpha1"
+)
+
+func TestClearNodeFailure(t *testing.T) {
+	g := NewWithT(t)
+
+	c := &RuleReadinessController{}
+
+	rule := &readinessv1alpha1.NodeReadinessRule{
+		Status: readinessv1alpha1.NodeReadinessRuleStatus{
+			FailedNodes: []readinessv1alpha1.NodeFailure{
+				{NodeName: "node-1", Reason: "EvaluationError", LastEvaluationTime: metav1.Now()},
+				{NodeName: "node-2", Reason: "EvaluationError", LastEvaluationTime: metav1.Now()},
+			},
+		},
+	}
+
+	c.clearNodeFailure(rule, "node-1")
+
+	g.Expect(rule.Status.FailedNodes).To(HaveLen(1))
+	g.Expect(rule.Status.FailedNodes[0].NodeName).To(Equal("node-2"))
+}
+
+func TestRecordThenClearNodeFailure(t *testing.T) {
+	g := NewWithT(t)
+
+	c := &RuleReadinessController{}
+
+	rule := &readinessv1alpha1.NodeReadinessRule{}
+
+	// A node fails evaluation and is recorded.
+	c.recordNodeFailure(rule, "node-1", "EvaluationError", "boom")
+	g.Expect(rule.Status.FailedNodes).To(HaveLen(1))
+
+	// The node later recovers; the failure record must be cleared.
+	c.clearNodeFailure(rule, "node-1")
+	g.Expect(rule.Status.FailedNodes).To(BeEmpty())
+}