Deploy a Kubernetes cluster using magnum Capi driver with autoscaling feature

In this section, we will deploy a kubernetes cluster with autoscaling feature Cluster Autoscaler.

1. Create a Kubernetes cluster with autoscaling enabled

   $ openstack coe cluster create --cluster-template \
   kubernetes-v1.31.1-ardc-syd-1-v5 --master-count 1 --node-count 1 \
   --labels auto_scaling_enabled=true,min_node_count=1,max_node_count=3 \
   --keypair <project key> mycluster
   Request to create cluster cae2a382-26a5-438d-bbdc-e694249bbede accepted
   
   

2. Verify status of autoscaling label

   $ openstack coe cluster show mycluster -c labels_added
   +--------------+--------------------------------------------------------------------------------+
   | Field        | Value                                                                          |
   +--------------+--------------------------------------------------------------------------------+
   | labels_added | {'auto_scaling_enabled': 'true', 'min_node_count': '1', 'max_node_count': '3'} |
   +--------------+--------------------------------------------------------------------------------+
   
   

3. Verify whether the cluster creation is successfully created

   $ openstack coe cluster list
   +--------------------------------------+-----------+---------+------------+--------------+--------------------+---------------+
   | uuid                                 | name      | keypair | node_count | master_count | status             | health_status |
   +--------------------------------------+-----------+---------+------------+--------------+--------------------+---------------+
   | cae2a382-26a5-438d-bbdc-e694249bbede | mycluster | xxxxxx  |          1 |            1 | UPDATE_COMPLETE    | HEALTHY       |
   +--------------------------------------+-----------+---------+------------+--------------+--------------------+---------------+
   
   

4. Download the kubeconfig file and verify the cluster nodes using kubectl in accordance with the Administering a Cluster in Kubernetes tutorial

5. Deploy an application - ngnix.yaml

   apiVersion: apps/v1
   kind: Deployment
   metadata:
     name: nginx-deployment
   spec:
     selector:
       matchLabels:
         app: nginx
     replicas: 3
     template:
       metadata:
         labels:
           app: nginx
       spec:
         containers:
         - name: nginx
           image: nginx:1.14.2
           ports:
           - containerPort: 80
   
   

   kubectl apply -f nginx.yaml
   

6. Deploy application and validate the deployment

   kubectl get deployments
   

   NAME               READY   UP-TO-DATE   AVAILABLE   AGE
   nginx-deployment   3/3     3            3           8m44s
   $ kubectl get pods
   NAME                               READY   STATUS    RESTARTS   AGE
   nginx-deployment-d556bf558-7phtc   1/1     Running   0          9m11s
   nginx-deployment-d556bf558-98d68   1/1     Running   0          9m11s
   nginx-deployment-d556bf558-shqt2   1/1     Running   0          9m11s
   $ kubectl get nodes
   NAME                                                STATUS   ROLES           AGE   VERSION
   mycluster-l76uten6iljx-control-plane-xlmq4          Ready    control-plane   42m   v1.31.1
   mycluster-l76uten6iljx-default-worker-4dqrj-cwmjq   Ready    <none>          39m   v1.31.1
   
   

7. Scaling up the nginx application deployment

   The number of NGINX web server replicas deployed must be carefully adjusted based on the configuration of the Kubernetes worker nodes. For example, in a cluster where each worker node is configured with 4 vCPUs and 8 GB of memory (m3.medium), a larger number of replicas may be required to saturate available resources and trigger the provisioning of additional nodes.

   kubectl scale deployment --replicas=120 nginx-deployment
   

   deployment.apps/nginx-deployment scaled
   
   

   kubectl get deployments
   

   NAME               READY     UP-TO-DATE   AVAILABLE   AGE
   nginx-deployment   101/120   120          101         14m
   $ kubectl get deployments
   NAME               READY     UP-TO-DATE   AVAILABLE   AGE
   nginx-deployment   120/120   120          120         20m
   $ os coe cluster list
   +--------------------------------------+-----------+---------+------------+--------------+-----------------+---------------+
   | uuid                                 | name      | keypair | node_count | master_count | status          | health_status |
   +--------------------------------------+-----------+---------+------------+--------------+-----------------+---------------+
   | cae2a382-26a5-438d-bbdc-e694249bbede | mycluster | xxxxxx  |          1 |            1 | CREATE_COMPLETE | HEALTHY       |
   +--------------------------------------+-----------+---------+------------+--------------+-----------------+---------------+
   $ kubectl get nodes
   NAME                                                STATUS   ROLES           AGE   VERSION
   mycluster-l76uten6iljx-control-plane-xlmq4          Ready    control-plane   51m   v1.31.1
   mycluster-l76uten6iljx-default-worker-4dqrj-br8p9   Ready    <none>          66s   v1.31.1
   mycluster-l76uten6iljx-default-worker-4dqrj-cwmjq   Ready    <none>          48m   v1.31.1
   
   

8. Scaling down the nginx application deployment

   kubectl scale deployment --replicas=2 nginx-deployment
   

   deployment.apps/nginx-deployment scaled
   
   

   kubectl get deployments
   

   NAME               READY   UP-TO-DATE   AVAILABLE   AGE
   nginx-deployment   2/2     2            2           37m
   $ kubectl get nodes
   NAME                                                STATUS   ROLES           AGE   VERSION
   mycluster-l76uten6iljx-control-plane-xlmq4          Ready    control-plane   100m   v1.31.1
   mycluster-l76uten6iljx-default-worker-4dqrj-cwmjq   Ready    <none>          97m    v1.31.1
   $ os coe cluster list
   +--------------------------------------+-----------+---------+------------+--------------+-----------------+---------------+
   | uuid                                 | name      | keypair | node_count | master_count | status          | health_status |
   +--------------------------------------+-----------+---------+------------+--------------+-----------------+---------------+
   | cae2a382-26a5-438d-bbdc-e694249bbede | mycluster | xxxxxx  |          1 |            1 | CREATE_COMPLETE | HEALTHY       |
   +--------------------------------------+-----------+---------+------------+--------------+-----------------+---------------+
   
   

Note: Please allow several minutes for the scale-down process to complete, as the typical duration ranges between 7 and 10 minutes.

More information

For more information, refer to:

• Cluster Autoscaler