Configuring autoscaling

Managed Service for Kubernetes has three autoscaling methods available:

• Cluster autoscaling
• Horizontal pod autoscaling
• Vertical pod autoscaling

Getting startedGetting started

1. Create a Managed Service for Kubernetes cluster with any suitable configuration.

2. Install kubectl and configure it to work with the created cluster.

Configuring cluster autoscalingConfiguring cluster autoscaling

To create an autoscalable Managed Service for Kubernetes node group:

Cluster Autoscaler is managed on the Managed Service for Kubernetes side.

For more information about Cluster Autoscaler, see Cluster autoscaling. The default parameters are described in the Kubernetes documentation.

See also Questions and answers about node group autoscaling in Managed Service for Kubernetes.

Configuring horizontal pod autoscalingConfiguring horizontal pod autoscaling

For more information about Horizontal Pod Autoscaler, see Horizontal pod autoscaling.

Configuring vertical pod autoscalingConfiguring vertical pod autoscaling

For more information about Vertical Pod Autoscaler, see Vertical pod autoscaling.

Deleting Terminated podsDeleting Terminated pods

Sometimes during autoscaling, Managed Service for Kubernetes node pods are not deleted and stay in the Terminated status. This happens because the Pod garbage collector (PodGC) fails to timely delete these pods.

You can delete the stuck Managed Service for Kubernetes pods:

• Manually
• Automatically using CronJob

ManuallyManually

Run this command:

kubectl get pods --all-namespaces | grep -i Terminated \
| awk '{print $1, $2}' | xargs -n2 kubectl delete pod -n

Automatically using CronJobAutomatically using CronJob

To delete stuck Managed Service for Kubernetes pods automatically:

1. Set up a CronJob.
2. Check the results of your CronJob jobs.

If you no longer need the CronJob, delete it.

Setting up automatic deletion in a CronJobSetting up automatic deletion in a CronJob

1. Create a cronjob.yaml file with a specification for the CronJob and the resources needed to run it:

   ---
   apiVersion: batch/v1
   kind: CronJob
   metadata:
     name: terminated-pod-cleaner
   spec:
     schedule: "*/5 * * * *"
     jobTemplate:
       spec:
         template:
           spec:
             serviceAccountName: terminated-pod-cleaner
             containers:
             - name: terminated-pod-cleaner
               image: bitnami/kubectl
               imagePullPolicy: IfNotPresent
               command: ["/bin/sh", "-c"]
               args: ["kubectl get pods --all-namespaces | grep -i Terminated | awk '{print $1, $2}' | xargs --no-run-if-empty -n2 kubectl delete pod -n"]
             restartPolicy: Never
   
   ---
   apiVersion: v1
   kind: ServiceAccount
   metadata:
     name: terminated-pod-cleaner
   
   ---
   apiVersion: rbac.authorization.k8s.io/v1
   kind: ClusterRole
   metadata:
     name: terminated-pod-cleaner
   rules:
     - apiGroups: [""]
       resources:
         - pods
       verbs: [list, delete]
   
   ---
   apiVersion: rbac.authorization.k8s.io/v1
   kind: ClusterRoleBinding
   metadata:
     name: terminated-pod-cleaner
   subjects:
   - kind: ServiceAccount
     name: terminated-pod-cleaner
     namespace: default
   roleRef:
     kind: ClusterRole
     name: terminated-pod-cleaner
     apiGroup: rbac.authorization.k8s.io
   

   The schedule: "*/5 * * * *" line defines a schedule in cron format: the job runs every 5 minutes. Change the interval if needed.

2. Create a CronJob and its resources:

   kubectl create -f cronjob.yaml
   

   Result:

   cronjob.batch/terminated-pod-cleaner created
   serviceaccount/terminated-pod-cleaner created
   clusterrole.rbac.authorization.k8s.io/terminated-pod-cleaner created
   clusterrolebinding.rbac.authorization.k8s.io/terminated-pod-cleaner created
   

3. Check that the CronJob has been created:

   kubectl get cronjob terminated-pod-cleaner
   

   Result:

   NAME                    SCHEDULE     SUSPEND  ACTIVE  LAST SCHEDULE  AGE
   terminated-pod-cleaner  */5 * * * *  False    0       <none>         4s
   

   After the interval specified in the SCHEDULE, a time value will appear in the LAST SCHEDULE column. This means that the task was successfully executed or ended with an error.

Checking the results of CronJob jobsChecking the results of CronJob jobs

1. Retrieve a list of jobs:

   kubectl get jobs
   

   Result:

   NAME           COMPLETIONS  DURATION  AGE
   <job_name>  1/1          4s        2m1s
   ...
   

2. Get the name of the Managed Service for Kubernetes pod that ran the job:

   kubectl get pods --selector=job-name=<job_name> --output=jsonpath={.items[*].metadata.name}
   

3. View the Managed Service for Kubernetes pod logs:

   kubectl logs <pod_name>
   

   The log will include a list of deleted Managed Service for Kubernetes pods. If the log is empty, this means that there were no Managed Service for Kubernetes pods in the Terminated status when the job ran.

Deleting the CronJobDeleting the CronJob

To delete the CronJob and its resources, run this command:

kubectl delete cronjob terminated-pod-cleaner && \
kubectl delete serviceaccount terminated-pod-cleaner && \
kubectl delete clusterrole terminated-pod-cleaner && \
kubectl delete clusterrolebinding terminated-pod-cleaner