You can create an application that has Horizontal Pod Autoscaling (HPA) enabled in the Container Service for Kubernetes (ACK) console. HPA can automatically scale container resources for your application. You can also use YAML files to describe HPA settings.
Before you enable HPA, make sure that you have completed the following steps:
Create an application that has HPA enabled in the ACK console
ACK is integrated with HPA. You can create an application that has HPA enabled in the ACK console. You can enable HPA when you create an application or after the application is created.
Enable HPA when you create an application
- Log on to the ACK console.
- In the left-side navigation pane of the ACK console, click Clusters.
- On the Clusters page, find the cluster that you want to manage and click the name of the cluster, or click Details in the Actions column. The details page of the cluster appears.
- In the left-side navigation pane of the details page, choose .
- On the Deployments tab, click Create from Image.
- On the Basic Information wizard page, enter an application name, select a cluster and a namespace to deploy
the application, and then click Next.
Parameter Description Name The name of the application. Namespace The namespace where you want to deploy the application. The default namespace is automatically selected. You can select another namespace. Replicas The number of pods that are provisioned for the application. Default value: 2. Type The type of application. You can select Deployments, StatefulSets, Jobs, Cron Jobs, or DaemonSets. Label Add a label to the application. The label is used to identify the application. Annotations Add an annotation to the application. Synchronize Timezone Specify whether to synchronize the time zone between nodes and containers.
- On the Container wizard page, set the container parameters, select an image, and configure the required
computing resources. Click Next. For more information, see Configure containers for an application.Note You must configure the required computing resources for the Deployment. Otherwise, you cannot enable HPA.
- On the Advanced wizard page, find the Access Control section, click Create on the right side of Services, and then set the parameters. For more information, see Configure advanced settings for an application.
- On the Advanced wizard page, select Enable for HPA and configure the scaling threshold and related settings.
- Metric: Select CPU Usage or Memory Usage. The selected resource type must be the same as the one that you have specified in the Required Resources parameter.
- Condition: Specify the resource usage threshold. HPA triggers scaling activities when the threshold is exceeded.
- Max. Replicas: Specify the maximum number of pods to which the Deployment can be scaled.
- Min. Replicas: Specify the minimum number of pods that must run for the Deployment.
- In the lower-right corner of the Advanced wizard page, click Create. The application is created with HPA enabled. Check the results
Click View Details or choose . On the page that appears, click the name of the created application or click Details in the Actions column. Then, click the Horizontal Pod Autoscaler tab to view information about the scaling group of the application.
- After the application starts running, container resources are automatically scaled based on the CPU usage. You can also check whether HPA is enabled in the staging environment by performing a CPU stress test on the application pods. Verify that the pods are automatically scaled within 30 seconds.
Enable HPA after an application is created
- On the Deployments tab, find and click the application for which you want to enable HPA.
- Click the Horizontal Pod Autoscaler tab and click Create on the right side of HPA.
- In the Create dialog box, configure the HPA settings. For more information about how to set the parameters, see HPA settings in Step 9.
- Click OK.
Run kubectl commands to enable HPA
You can also create a Horizontal Pod Autoscaler by using an orchestration template and associate the Horizontal Pod Autoscaler with the Deployment for which you want to enable HPA. Then, you can run kubectl commands to enable HPA.
In the following example, HPA is enabled for an NGINX application.
- Create a file named nginx.yml and copy the following content into the file.The following code block is a YAML template that is used to create a Deployment:
apiVersion: apps/v1 kind: Deployment metadata: name: nginx labels: app: nginx spec: replicas: 2 selector: matchLabels: app: nginx template: metadata: labels: app: nginx spec: containers: - name: nginx image: nginx:1.7.9 # replace it with your exactly <image_name:tags> ports: - containerPort: 80 resources: requests: ##This parameter is required to run the Horizontal Pod Autoscaler. cpu: 500m
- Run the following command to create an NGINX application:
kubectl create -f nginx.yml
- Create a Horizontal Pod Autoscaler.Use scaleTargetRef to associate the Horizontal Pod Autoscaler with the Deployment named nginx.
apiVersion: autoscaling/v2beta1 kind: HorizontalPodAutoscaler metadata: name: nginx-hpa namespace: default spec: scaleTargetRef: ##Associate the Horizontal Pod Autoscaler with the Deployment named nginx. apiVersion: apps/v1 kind: Deployment name: nginx minReplicas: 1 maxReplicas: 10 metrics: - type: Resource resource: name: cpu targetAverageUtilization: 50Note You must configure the requested resources for the application pods. Otherwise, the Horizontal Pod Autoscaler cannot be started.
- Run the
kubectl describe hpa namecommand. The following output is an example of a warning that is returned:
Warning FailedGetResourceMetric 2m (x6 over 4m) horizontal-pod-autoscaler missing request for cpu on container nginx in pod default/nginx-deployment-basic-75675f5897-mqzs7 Warning FailedComputeMetricsReplicas 2m (x6 over 4m) horizontal-pod-autoscaler failed to get cpu utilization: missing request for cpu on container nginx in pod default/nginx-deployment-basic-75675f5
- After the Horizontal Pod Autoscaler is created, run the
kubectl describe hpa namecommand.If the following output is returned, it indicates that the Horizontal Pod Autoscaler is running as expected:
Normal SuccessfulRescale 39s horizontal-pod-autoscaler New size: 1; reason: All metrics below target
If the pod usage of the NGINX application exceeds 50% as configured in the HPA settings, the Horizontal Pod Autoscaler automatically scales out the pods. If the pod usage of the NGINX application drops below 50%, the Horizontal Pod Autoscaler automatically scales in the pods.