What feature should you configure to automate scaling in Google Kubernetes Engine (GKE) for a microservice application?

To automate scaling in Google Kubernetes Engine (GKE) for a microservice application, configuring the Horizontal Pod Autoscaler (HPA) along with enabling the cluster autoscaler is an effective approach.

The Horizontal Pod Autoscaler adjusts the number of pod replicas based on observed CPU utilization (or other select metrics) within the deployment. This allows your application to dynamically respond to changes in load, ensuring that there are enough instances of the microservice running during peak demand and scaling down when the load decreases to optimize resource usage and costs.

Enabling the cluster autoscaler complements the HPA by allowing the GKE cluster to automatically adjust the number of nodes in the node pool. When the HPA scales up the number of pods, if there are not enough resources in the current node pool to accommodate the new pods, the cluster autoscaler can provision additional nodes to handle the load. Conversely, it can also scale down the node pool when there are fewer pods being utilized, which helps in resource optimization and cost efficiency.

The other options do not provide this comprehensive scaling capability. For instance, using a Vertical Pod Autoscaler focuses on adjusting the resource requests and limits for individual pods rather than scaling the number of pod replicas to handle load. Furthermore, combining the Vertical