基于活动会话配置 Kube.netes HPA

Question

Is there a way to configure Kube.netes Horizontal Pod Autoscaler based on the sessions which the pod has? For example, we have an application which stores user sessions. I have configured HPA to trigger based on CPU. But the issue is when the HPA scales down, the active session also gets disrupted since the pod is deleted. Is there a custom metric or a way we can configure this?

Answer 1

HPA can make scaling decisions based on custom or externally provided metrics and works automatically after initial configuration. All you need to do is define the MIN and MAX number of replicas.

Once configured, the Horizontal Pod Autoscaler controller is in charge of checking the metrics and then scaling your replicas up or down accordingly. By default, HPA checks metrics every 15 seconds.

To check metrics, HPA depends on another Kube.netes resource known as the Metrics Server. The Metrics Server provides standard resource usage measurement data by capturing data from “kube.netes.summary_api” such as CPU and memory usage for nodes and pods. It can also provide access to custom metrics ( that can be collected from an external source ) like the number of active sessions on a load balancer indicating traffic volume.

Try Session affinity which provides a best-effort attempt to send requests from a particular client to the same backend for as long as the backend is healthy and has the capacity, according to the configured balancing mode.

When you use session affinity, we recommend the RATE balancing mode rather than UTILIZATION. Session affinity works best if you set the balancing mode to requests per second (RPS).

Please go throughKube.netes HPA for more information.