How to use the Kubernetes HorizontalPodAutoscaler with the memory metric?

Question

I'm trying to understand how the Kubernetes HorizontalPodAutoscaler works. Until now, I have used the following configuration:

apiVersion: autoscaling/v1
kind: HorizontalPodAutoscaler
metadata:
  name: my-deployment
spec:
  scaleTargetRef:
    apiVersion: apps/v1
    kind: Deployment
    name: my-deployment
  minReplicas: 1
  maxReplicas: 10
  targetCPUUtilizationPercentage: 50

This uses the targetCPUUtilizationPercentage parameter but I would like to use a metric for the memory percentage used, but I was not able to find any example. Any hint?

I found also that there is this type of configuration to support multiple metrics, but the apiVersion is autoscaling/v2alpha1. Can this be used in a production environment?

kind: HorizontalPodAutoscaler
apiVersion: autoscaling/v2alpha1
metadata:
  name: WebFrontend
spec:
  scaleTargetRef:
    kind: ReplicationController
    name: WebFrontend
  minReplicas: 2
  maxReplicas: 10
  metrics:
  - type: Resource
    resource:
      name: cpu
      targetAverageUtilization: 80
  - type: Object
    object:
      target:
        kind: Service
        name: Frontend
      metricName: hits-per-second
      targetValue: 1k

Answer 1

Here is a manifest example for what you need, that includes Memory Metrics:

apiVersion: autoscaling/v2beta2
kind: HorizontalPodAutoscaler
metadata:
  name: web-servers
spec:
  scaleTargetRef:
    apiVersion: apps/v1
    kind: Deployment
    name: web-servers
  minReplicas: 1
  maxReplicas: 10
  metrics:
  - type: Resource
    resource:
      name: cpu
      target:
        type: Utilization
        averageUtilization: 20
  - type: Resource
    resource:
      name: memory
      target:
        type: AverageValue
        averageValue: 30Mi

An important thing to notice is that, as you can see, it uses the autoscaling/v2beta2 API version, so you need to follow all the previous instructions listed here.

Regarding the possibility to use the autoscaling/v2alpha1, yes, you can use it, as it includes support for scaling on memory and custom metrics as this URL specifies, but keep in mind that alpha versions are released for testing, as they are not final versions.

For more autoscaling/v2beta2 YAML’s examples and a deeper look into memory metrics, you can take a look at this thread.