tencent cloud

Overview

Horizontal Pod Autoscaler (HPA) can automatically scale the number of Pods for services according to the average CPU utilization of target Pods and other metrics. This document describes how to implement Pod autoscaling via Tencent Cloud TKE console.

How it Works

The HPA backend components pull monitoring metrics of containers and Pods from Tencent Cloud’s Cloud Monitor every 15 seconds and calculate the desired number of replicas based on the current monitoring data, the current number of replicas, and the desired value of the metrics. When there is a gap between the desired number and the actual number of replicas, HPA will trigger a Deployment to adjust the number of Pod replicas, thereby achieving auto-scaling.
Take CPU utilization as an example. Suppose there are two Pods with an average CPU utilization of 90%, and the target CPU utilization is set to 60% for autoscaling. Then the number of Pods will be automatically adjusted as follows: 90% × 2 / 60% = 3 Pods.

Note：

If you set multiple auto scaling metrics, HPA will separately calculate the target numbers of replicas according to each metric and then take the maximum number to use for auto scaling.

Notes

• If you choose CPU utilization (by request) as the metric type, a CPU request must be set for the container.
• Set reasonable targets for the policy metrics. For example, set 70% for containers and applications and leave 30%.
• Keep Pods and nodes healthy; avoid frequently recreating Pods.
• Ensure that the load balancer works stably.
• If the gap between the actual number and desired number of replicas is smaller than 10%, HPA will not adjust the number of replicas.
• If the value of Deployment.spec.replicas corresponding to the service is 0, HPA will not work.
• If multiple HPAs are bound to a single Deployment, the HPAs will take effect simultaneously, which will cause workload replicas to be repeatedly scaled.

Prerequisites

• You have registered a Tencent Cloud account.
• You have logged in to the TKE console.
• You have created a cluster. For more information, see Creating a Cluster.

Directions

Enabling Auto Scaling

You can enable auto scaling in one of the following ways.

Setting auto-adjustment of the number of Pods

1. On the Cluster Management page, click the cluster ID for which a scaling group is to be created.
2. Select Workload > Deployment. On the Deployment page, click Create.
3. On the Create Deployment page, select Auto adjustment for the number of Pods as shown below:
   

• Trigger Policy: the policy metrics that trigger the auto-scaling. For details, see Metric Type.
• Number of Pods: enter the minimum and maximum numbers according to your needs. The number of Pods will be auto-adjusted within the range.

Creating auto-scaling group

1. On the Cluster Management page, click the cluster ID for which a scaling group is to be created.
2. Select Auto Scaling > HorizontalPodAutoscaler. On the HorizontalPodAutoscaler page, and click Create.
3. On the Create HPA page, configure the HPA as needed.
   

• Name: Enter the name of the auto scaling group to be created.
• Namespace: select based on your needs.
• Workload Type: select based on your needs.
• Associated Workload: select based on your needs. The value cannot be empty.
• Trigger Policy: the policy metrics that trigger the auto-scaling. For details, see Metric Type.
• Number of Pods: enter the minimum and maximum numbers according to your needs. The number of Pods will be auto-adjusted within the range.

4. Click Create HPA.

Creating using YAML

1. On the Cluster Management page, click the cluster ID for which a scaling group is to be created.
2. On the cluster basic information page, click Creating using YAML in the top right corner.
   
3. Edit the content according to your needs and click Complete to create the HPA.

Updating Auto Scaling Rules

You can update auto scaling rules in one of the following ways.

Updating the Pod Quantity

1. On the Cluster Management page, click the target cluster ID.
2. Select Workload > Deployment to enter the Deployment page and click Update Pod Number.
   
3. On the Update Pod Number page, select Auto adjustment and set parameters as needed.
   
4. Click Update number of instance.

Modifying HPA Configuration

1. On the Cluster Management page, click the cluster ID for which a scaling group is to be created.
2. Select Auto Scaling > HorizontalPodAutoscaler. On the HorizontalPodAutoscaler page, click Modify configuration in the Operation column of the HPA whose configuration is to be updated.
   
3. On the Update Configuration page, change the settings according to your needs and click Update HPA.

Editing YAML

1. On the Cluster Management page, click the cluster ID for which a scaling group is to be created.
2. Select Auto Scaling > HorizontalPodAutoscaler. On the HorizontalPodAutoscaler page, click Edit YAML in the Operation column of the HPA whose configuration is to be updated.
   
3. On the Edit YAML page, edit parameters as needed and click Complete.

Metric Type

For more information on metrics and types, see HPA Metrics.