Fix: pdb-min-available when Replica number is controlled via HPA

e2etests/bats-tests.sh

@@ -638,8 +638,12 @@ get_value_from() {
 
 
   message1=$(get_value_from "${lines[0]}" '.Reports[0].Object.K8sObject.GroupVersionKind.Kind + ": " + .Reports[0].Diagnostic.Message')
+  message2=$(get_value_from "${lines[0]}" '.Reports[1].Object.K8sObject.GroupVersionKind.Kind + ": " + .Reports[1].Diagnostic.Message')
+  count=$(get_value_from "${lines[0]}" '.Reports | length')
 
   [[ "${message1}" == "PodDisruptionBudget: The current number of replicas for deployment foo is equal to or lower than the minimum number of replicas specified by its PDB." ]]
+  [[ "${message2}" == "PodDisruptionBudget: The current number of replicas for deployment foo2 is equal to or lower than the minimum number of replicas specified by its PDB." ]]
+  [[ "${count}" == "2" ]]
 }
 
 @test "privilege-escalation-container" {

pkg/extract/hpa_spec.go

@@ -31,3 +31,19 @@ func checkReplicas(minReplicas *int32) (int32, bool) {
 	// If numReplicas is a `nil` pointer, then it defaults to 1.
 	return 1, true
 }
+
+// HPAScaleTargetRefName extracts Spec.ScaleTargetRef.Name
+func HPAScaleTargetRefName(obj k8sutil.Object) (string, bool) {
+	switch hpa := obj.(type) {
+	case *autoscalingV2Beta1.HorizontalPodAutoscaler:
+		return hpa.Spec.ScaleTargetRef.Name, true
+	case *autoscalingV2Beta2.HorizontalPodAutoscaler:
+		return hpa.Spec.ScaleTargetRef.Name, true
+	case *autoscalingV2.HorizontalPodAutoscaler:
+		return hpa.Spec.ScaleTargetRef.Name, true
+	case *autoscalingV1.HorizontalPodAutoscaler:
+		return hpa.Spec.ScaleTargetRef.Name, true
+	default:
+		return "", false
+	}
+}

pkg/templates/pdbminavailable/template.go

@@ -90,7 +90,10 @@ func minAvailableCheck(lintCtx lintcontext.LintContext, object lintcontext.Objec
 		}
 	}
 
-	// Evaluate Deploymet Likes in the lintContext to see if they have MinAvailable set too low
+	// Builds an HPA map for that namespace in case there is no replicas set on deployment
+	hpa := getHorizontalPodAutoscalers(lintCtx, pdb.Namespace)
+
+	// Evaluate Deployment Likes in the lintContext to see if they have MinAvailable set too low
 	deploymentLikes, err := getDeploymentLikeObjects(lintCtx, labelSelector, pdb.Namespace)
 	if err != nil {
 		return []diagnostic.Diagnostic{
@@ -103,6 +106,10 @@ func minAvailableCheck(lintCtx lintcontext.LintContext, object lintcontext.Objec
 	for _, dl := range deploymentLikes {
 		pdbMinAvailable := value
 		replicas, _ := extract.Replicas(dl)
+		if int(replicas) == 1 {
+			// if replicas number not set on deployment, use HPA MinReplicas
+			replicas = transformReplicaIntoMinReplicas(dl, hpa, replicas)
+		}
 		if isPercent {
 			// Calulate the actual value of the MinAvailable with respect to the Replica count if a percentage is set
 			pdbMinAvailable = int(math.Ceil(float64(replicas) * (float64(value) / float64(100))))
@@ -137,10 +144,6 @@ func getDeploymentLikeObjects(lintCtx lintcontext.LintContext, labelSelector lab
 		if !exists {
 			continue
 		}
-		// If there are no Replicas set on the Deployment Like, it's not possible to compare to a PDB
-		if _, ok := extract.Replicas(obj.K8sObject); !ok {
-			continue
-		}
 
 		objLabelSelector, err := metaV1.LabelSelectorAsSelector(selectors)
 		if err != nil {
@@ -177,3 +180,39 @@ func getIntOrPercentValueSafelyFromString(intOrStr string) (int, bool, error) {
 	}
 	return v, true, nil
 }
+
+// Function to get the list of HPA's provided
+func getHorizontalPodAutoscalers(lintCtx lintcontext.LintContext, namespace string) map[string]k8sutil.Object {
+
+	m := make(map[string]k8sutil.Object, len(lintCtx.Objects()))
+
+	for _, obj := range lintCtx.Objects() {
+		// Ensure that only HPA objects are processed
+		if obj.GetK8sObjectName().GroupVersionKind.Kind != objectkinds.HorizontalPodAutoscaler {
+			continue
+		}
+
+		// Ensure that only HPAs are in the same namespaces as the PDB
+		if obj.GetK8sObjectName().Namespace != namespace {
+			continue
+		}
+		// validate object with HPA versions using the HPAScaleTargetRefName extractor package function and add to map
+		hpaSpecScaleTargetRefName, ok := extract.HPAScaleTargetRefName(obj.K8sObject)
+		if !ok {
+			continue
+		}
+		m[hpaSpecScaleTargetRefName] = obj.K8sObject
+	}
+
+	return m
+}
+
+// Function to transform the replica count into the minReplicas count if the deployment has a HPA with a minReplicas set
+func transformReplicaIntoMinReplicas(deployment k8sutil.Object, hpaMap map[string]k8sutil.Object, replicas int32) int32 {
+	hpa := hpaMap[deployment.GetName()]
+	hpaMinReplicas, ok := extract.HPAMinReplicas(hpa)
+	if !ok {
+		return replicas
+	}
+	return hpaMinReplicas
+}

pkg/templates/pdbminavailable/template_test.go

@@ -9,6 +9,7 @@ import (
 	"golang.stackrox.io/kube-linter/pkg/lintcontext/mocks"
 	"golang.stackrox.io/kube-linter/pkg/templates"
 	appsV1 "k8s.io/api/apps/v1"
+	autoscalingV2 "k8s.io/api/autoscaling/v2"
 	v1 "k8s.io/api/policy/v1"
 	metaV1 "k8s.io/apimachinery/pkg/apis/meta/v1"
 	"k8s.io/apimachinery/pkg/util/intstr"
@@ -177,3 +178,44 @@ func (p *PDBTestSuite) TestPDBMinAvailableOneHundredPercent() {
 		},
 	})
 }
+
+// test that the check run with a deployment that has no replicas and a HPA that has a minReplicas
+func (p *PDBTestSuite) TestPDBWithMinAvailableHPA() {
+	p.ctx.AddMockDeployment(p.T(), "test-deploy")
+	p.ctx.ModifyDeployment(p.T(), "test-deploy", func(deployment *appsV1.Deployment) {
+		deployment.Namespace = "test"
+		deployment.Spec.Replicas = nil
+		deployment.Spec.Selector = &metaV1.LabelSelector{}
+		deployment.Spec.Selector.MatchLabels = map[string]string{"foo": "bar"}
+	})
+	p.ctx.AddMockHorizontalPodAutoscaler(p.T(), "test-hpa", "v2")
+	p.ctx.ModifyHorizontalPodAutoscalerV2(p.T(), "test-hpa", func(hpa *autoscalingV2.HorizontalPodAutoscaler) {
+		hpa.Namespace = "test"
+		hpa.Spec.ScaleTargetRef = autoscalingV2.CrossVersionObjectReference{
+			Kind:       "Deployment",
+			Name:       "test-deploy",
+			APIVersion: "apps/v1",
+		}
+		hpa.Spec.MinReplicas = nil
+	})
+	p.ctx.AddMockPodDisruptionBudget(p.T(), "test-pdb")
+	p.ctx.ModifyPodDisruptionBudget(p.T(), "test-pdb", func(pdb *v1.PodDisruptionBudget) {
+		pdb.Namespace = "test"
+		pdb.Spec.Selector = &metaV1.LabelSelector{}
+		pdb.Spec.Selector.MatchLabels = map[string]string{"foo": "bar"}
+		pdb.Spec.MinAvailable = &intstr.IntOrString{StrVal: "50%", Type: intstr.String}
+	})
+
+	p.Validate(p.ctx, []templates.TestCase{
+		{
+			Param: params.Params{},
+			Diagnostics: map[string][]diagnostic.Diagnostic{
+				"test-pdb": {
+					{Message: "The current number of replicas for deployment test-deploy is equal to or lower than the minimum number of replicas specified by its PDB."},
+				},
+			},
+			ExpectInstantiationError: false,
+		},
+	})
+
+}

tests/checks/pdb-min-available.yaml

@@ -20,3 +20,44 @@ spec:
   selector:
     matchLabels:
       name: cloud-ingress-operator
+---
+apiVersion: policy/v1
+kind: PodDisruptionBudget
+metadata:
+  name: baz2
+  namespace: bar2
+spec:
+  minAvailable: 1
+  selector:
+    matchLabels:
+      name: cloud-ingress-operator2
+---
+apiVersion: autoscaling/v2beta1
+kind: HorizontalPodAutoscaler
+metadata:
+  name: app2
+  namespace: bar2
+spec:
+  minReplicas: 1
+  maxReplicas: 100
+  scaleTargetRef:
+    apiVersion: apps/v1
+    kind: Deployment
+    name: foo2
+    namespace: bar2
+  targetCPUUtilizationPercentage: 85
+---
+apiVersion: apps/v1
+kind: Deployment
+metadata:
+  name: foo2
+  namespace: bar2
+spec:
+  replicas: 1
+  selector:
+    matchLabels:
+      name: cloud-ingress-operator2
+  template:
+    metadata:
+      labels:
+        name: cloud-ingress-operator2