score/hpa: added a check for hpa min replicas > 1

Fixes #581

domain/kube-score.go

@@ -2,9 +2,9 @@ package domain
 
 import (
  "io"
+ autoscalingv1 "k8s.io/api/autoscaling/v1"
 
  appsv1 "k8s.io/api/apps/v1"
- autoscalingv1 "k8s.io/api/autoscaling/v1"
  corev1 "k8s.io/api/core/v1"
  networkingv1 "k8s.io/api/networking/v1"
  policyv1 "k8s.io/api/policy/v1"
@@ -49,6 +49,7 @@ type FileLocationer interface {
 type HpaTargeter interface {
  GetTypeMeta() metav1.TypeMeta
  GetObjectMeta() metav1.ObjectMeta
+ MinReplicas() *int32
  HpaTarget() autoscalingv1.CrossVersionObjectReference
  FileLocationer
 }

parser/internal/hpa.go

@@ -26,6 +26,9 @@ func (d HPAv1) GetTypeMeta() metav1.TypeMeta {
 func (d HPAv1) GetObjectMeta() metav1.ObjectMeta {
  return d.ObjectMeta
 }
+func (d HPAv1) MinReplicas() *int32 {
+ return d.Spec.MinReplicas
+}
 
 func (d HPAv1) HpaTarget() autoscalingv1.CrossVersionObjectReference {
  return d.Spec.ScaleTargetRef
@@ -48,6 +51,10 @@ func (d HPAv2beta1) GetObjectMeta() metav1.ObjectMeta {
  return d.ObjectMeta
 }
 
+func (d HPAv2beta1) MinReplicas() *int32 {
+ return d.Spec.MinReplicas
+}
+
 func (d HPAv2beta1) HpaTarget() autoscalingv1.CrossVersionObjectReference {
  return autoscalingv1.CrossVersionObjectReference(d.Spec.ScaleTargetRef)
 }
@@ -69,6 +76,10 @@ func (d HPAv2beta2) GetObjectMeta() metav1.ObjectMeta {
  return d.ObjectMeta
 }
 
+func (d HPAv2beta2) MinReplicas() *int32 {
+ return d.Spec.MinReplicas
+}
+
 func (d HPAv2beta2) HpaTarget() autoscalingv1.CrossVersionObjectReference {
  return autoscalingv1.CrossVersionObjectReference(d.Spec.ScaleTargetRef)
 }
@@ -90,6 +101,10 @@ func (d HPAv2) GetObjectMeta() metav1.ObjectMeta {
  return d.ObjectMeta
 }
 
+func (d HPAv2) MinReplicas() *int32 {
+ return d.Spec.MinReplicas
+}
+
 func (d HPAv2) HpaTarget() autoscalingv1.CrossVersionObjectReference {
  return autoscalingv1.CrossVersionObjectReference(d.Spec.ScaleTargetRef)
 }

score/apps/apps_test.go

@@ -355,6 +355,10 @@ func (d hpav1) GetObjectMeta() metav1.ObjectMeta {
  return d.ObjectMeta
 }
 
+func (d hpav1) MinReplicas() *int32 {
+ return d.Spec.MinReplicas
+}
+
 func (d hpav1) HpaTarget() autoscalingv1.CrossVersionObjectReference {
  return d.Spec.ScaleTargetRef
 }

score/deployment/deployment.go

@@ -91,9 +91,12 @@ func deploymentReplicas(svcs []ks.Service, hpas []ks.HpaTargeter) func(deploymen
  }
  }
 
- if !referencedByService || hasHPA {
+ if !referencedByService {
  score.Skipped = true
- score.AddComment("", "Skipped as the Deployment is not targeted by service or is controlled by a HorizontalPodAutoscaler", "")
+ score.AddComment("", "Skipped as the Deployment is not targeted by service", "")
+ } else if hasHPA {
+ score.Skipped = true
+ score.AddComment("", "Skipped as the Deployment is controlled by a HorizontalPodAutoscaler", "")
  } else {
  if ptr.Deref(deployment.Spec.Replicas, 1) >= 2 {
  score.Grade = scorecard.GradeAllOK

score/deployment_test.go

@@ -39,10 +39,14 @@ func TestServiceTargetsDeploymentReplicasOk(t *testing.T) {
 
 func TestServiceNotTargetsDeploymentReplicasNotRelevant(t *testing.T) {
  t.Parallel()
- skipped := wasSkipped(t, config.Configuration{
+ assert.True(t, wasSkipped(t, config.Configuration{
+ AllFiles: []ks.NamedReader{testFile("service-not-target-deployment.yaml")},
+ }, "Deployment Replicas"))
+
+ summaries := getSummaries(t, config.Configuration{
  AllFiles: []ks.NamedReader{testFile("service-not-target-deployment.yaml")},
  }, "Deployment Replicas")
- assert.True(t, skipped)
+ assert.Contains(t, summaries, "Skipped as the Deployment is not targeted by service")
 }
 
 func TestServiceTargetsDeploymentReplicasNok(t *testing.T) {
@@ -52,8 +56,12 @@ func TestServiceTargetsDeploymentReplicasNok(t *testing.T) {
 
 func TestHPATargetsDeployment(t *testing.T) {
  t.Parallel()
- skipped := wasSkipped(t, config.Configuration{
+ assert.True(t, wasSkipped(t, config.Configuration{
+ AllFiles: []ks.NamedReader{testFile("hpa-target-deployment.yaml")},
+ }, "Deployment Replicas"))
+
+ summaries := getSummaries(t, config.Configuration{
  AllFiles: []ks.NamedReader{testFile("hpa-target-deployment.yaml")},
  }, "Deployment Replicas")
- assert.True(t, skipped)
+ assert.Contains(t, summaries, "Skipped as the Deployment is controlled by a HorizontalPodAutoscaler")
 }

score/hpa/hpa.go

@@ -4,10 +4,12 @@ import (
  "github.com/zegl/kube-score/domain"
  "github.com/zegl/kube-score/score/checks"
  "github.com/zegl/kube-score/scorecard"
+ "k8s.io/utils/ptr"
 )
 
 func Register(allChecks *checks.Checks, allTargetableObjs []domain.BothMeta) {
  allChecks.RegisterHorizontalPodAutoscalerCheck("HorizontalPodAutoscaler has target", `Makes sure that the HPA targets a valid object`, hpaHasTarget(allTargetableObjs))
+ allChecks.RegisterHorizontalPodAutoscalerCheck("HorizontalPodAutoscaler Replicas", `Makes sure that the HPA has multiple replicas`, hpaHasMultipleReplicas())
 }
 
 func hpaHasTarget(allTargetableObjs []domain.BothMeta) func(hpa domain.HpaTargeter) (scorecard.TestScore, error) {
@@ -33,3 +35,15 @@ func hpaHasTarget(allTargetableObjs []domain.BothMeta) func(hpa domain.HpaTarget
  return
  }
 }
+
+func hpaHasMultipleReplicas() func(hpa domain.HpaTargeter) (scorecard.TestScore, error) {
+ return func(hpa domain.HpaTargeter) (score scorecard.TestScore, err error) {
+ if ptr.Deref(hpa.MinReplicas(), 1) >= 2 {
+ score.Grade = scorecard.GradeAllOK
+ } else {
+ score.Grade = scorecard.GradeWarning
+ score.AddComment("", "HPA few replicas", "HorizontalPodAutoscalers are recommended to have at least 2 replicas to prevent unwanted downtime.")
+ }
+ return
+ }
+}

score/hpa/hpa_test.go

@@ -177,6 +177,10 @@ func (d hpav1) GetObjectMeta() metav1.ObjectMeta {
  return d.ObjectMeta
 }
 
+func (d hpav1) MinReplicas() *int32 {
+ return d.Spec.MinReplicas
+}
+
 func (d hpav1) HpaTarget() v1.CrossVersionObjectReference {
  return d.Spec.ScaleTargetRef
 }

score/hpa_test.go

@@ -20,3 +20,13 @@ func TestHorizontalPodAutoscalerHasNoTarget(t *testing.T) {
  t.Parallel()
  testExpectedScore(t, "hpa-has-no-target.yaml", "HorizontalPodAutoscaler has target", scorecard.GradeCritical)
 }
+
+func TestHorizontalPodAutoscalerMinReplicasOk(t *testing.T) {
+ t.Parallel()
+ testExpectedScore(t, "hpa-min-replicas-ok.yaml", "HorizontalPodAutoscaler Replicas", scorecard.GradeAllOK)
+}
+
+func TestHorizontalPodAutoscalerMinReplicasNok(t *testing.T) {
+ t.Parallel()
+ testExpectedScore(t, "hpa-min-replicas-nok.yaml", "HorizontalPodAutoscaler Replicas", scorecard.GradeWarning)
+}

score/score_test.go

@@ -54,6 +54,25 @@ func wasSkipped(t *testing.T, config config.Configuration, testcase string) bool
  return false
 }
 
+func getSummaries(t *testing.T, config config.Configuration, testcase string) []string {
+ sc, err := testScore(config)
+ assert.NoError(t, err)
+ var summaries []string
+ for _, objectScore := range sc {
+ for _, s := range objectScore.Checks {
+ if s.Check.Name == testcase {
+ for _, c := range s.Comments {
+ summaries = append(summaries, c.Summary)
+ }
+ return summaries
+ }
+ }
+ }
+
+ assert.Fail(t, "test was not run")
+ return summaries
+}
+
 func testScore(config config.Configuration) (scorecard.Scorecard, error) {
  p, err := parser.New()
  if err != nil {

score/testdata/hpa-min-replicas-nok.yaml

@@ -0,0 +1,31 @@
+apiVersion: autoscaling/v2
+kind: HorizontalPodAutoscaler
+metadata:
+ name: php-apache
+ namespace: default
+spec:
+ scaleTargetRef:
+ apiVersion: apps/v1
+ kind: Deployment
+ name: php-apache
+ minReplicas: 1
+ maxReplicas: 10
+ metrics:
+ - type: Resource
+ resource:
+ name: cpu
+ target:
+ type: Utilization
+ averageUtilization: 50
+---
+apiVersion: apps/v1
+kind: Deployment
+metadata:
+ name: php-apache
+ namespace: default
+spec:
+ template:
+ spec:
+ containers:
+ - name: foo
+ image: foo:latest

score/testdata/hpa-min-replicas-ok.yaml

@@ -0,0 +1,31 @@
+apiVersion: autoscaling/v2
+kind: HorizontalPodAutoscaler
+metadata:
+ name: php-apache
+ namespace: default
+spec:
+ scaleTargetRef:
+ apiVersion: apps/v1
+ kind: Deployment
+ name: php-apache
+ minReplicas: 2
+ maxReplicas: 10
+ metrics:
+ - type: Resource
+ resource:
+ name: cpu
+ target:
+ type: Utilization
+ averageUtilization: 50
+---
+apiVersion: apps/v1
+kind: Deployment
+metadata:
+ name: php-apache
+ namespace: default
+spec:
+ template:
+ spec:
+ containers:
+ - name: foo
+ image: foo:latest

score/testdata/hpa-target-deployment.yaml

@@ -26,7 +26,23 @@ metadata:
 spec:
  replicas: 1
  template:
+ metadata:
+ labels:
+ app: my-app
  spec:
  containers:
  - name: foo
- image: foo:latest
+ image: foo:latest
+---
+kind: Service
+apiVersion: v1
+metadata:
+ name: my-service
+ namespace: default
+spec:
+ selector:
+ app: my-app
+ ports:
+ - protocol: TCP
+ port: 80
+ targetPort: 8080