HPA targeted deployments with configured replica count

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Metadata

Id: 5744cbb8-5946-4b75-a196-ade44449525b

Cloud Provider: Kubernetes

Platform: Kubernetes

Severity: Low

Category: Availability

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Description

Deployments targeted by HorizontalPodAutoscaler should not include a statically configured replica count. This rule flags Deployments referenced by an HPA via the scaleTargetRef when the Deployment’s spec.replicas field is defined. A defined spec.replicas can conflict with the HPA’s scaling decisions and should be undefined so the HorizontalPodAutoscaler can manage replica count.

Compliant Code Examples

#this code is a correct code for which the query should not find any result
apiVersion: apps/v1
kind: Deployment
metadata:
  name: php-apache
spec:
  selector:
    matchLabels:
      run: php-apache
  template:
    metadata:
      labels:
        run: php-apache
    spec:
      containers:
      - name: php-apache
        image: k8s.gcr.io/hpa-example
        ports:
        - containerPort: 80
        resources:
          limits:
            cpu: 500m
          requests:
            cpu: 200m

Non-Compliant Code Examples

#this is a problematic code where the query should report a result(s)
apiVersion: apps/v1
kind: Deployment
metadata:
  name: php-apache-1
spec:
  selector:
    matchLabels:
      run: php-apache
  replicas: 1
  template:
    metadata:
      labels:
        run: php-apache
    spec:
      containers:
      - name: php-apache
        image: k8s.gcr.io/hpa-example
        ports:
        - containerPort: 80
        resources:
          limits:
            cpu: 500m
          requests:
            cpu: 200m
---
apiVersion: autoscaling/v2beta2
kind: HorizontalPodAutoscaler
metadata:
  name: php-apache
spec:
  scaleTargetRef:
    apiVersion: apps/v1
    kind: Deployment
    name: php-apache-1
  minReplicas: 1
  maxReplicas: 10
  metrics:
  - type: Resource
    resource:
      name: cpu
      target:
        type: Utilization
        averageUtilization: 50