OpenShift Container Platform

Enable node auto-scaling for the hosted cluster

When you need more capacity in your hosted cluster and spare agents are available, you can enable auto-scaling to install new worker nodes.

Procedure

To enable auto-scaling, enter the following command:

$ oc -n <hosted_cluster_namespace> patch nodepool <hosted_cluster_name> \
  --type=json \
  -p '[{"op": "remove", "path": "/spec/replicas"},{"op":"add", "path": "/spec/autoScaling", "value": { "max": 5, "min": 2 }}]'

In the example, the minimum number of nodes is 2, and the maximum is 5. The maximum number of nodes that you can add might be bound by your platform. For example, if you use the Agent platform, the maximum number of nodes is bound by the number of available agents.

Create a workload that requires a new node.

Create a YAML file that has the workload configuration, by using the following example:

apiVersion: apps/v1
kind: Deployment
metadata:
  creationTimestamp: null
  labels:
    app: reversewords
  name: reversewords
  namespace: default
spec:
  replicas: 40
  selector:
    matchLabels:
      app: reversewords
  strategy: {}
  template:
    metadata:
      creationTimestamp: null
      labels:
        app: reversewords
    spec:
      containers:
      - image: quay.io/mavazque/reversewords:latest
        name: reversewords
        resources:
          requests:
            memory: 2Gi
status: {}

Save the file as workload-config.yaml.
Apply the YAML by entering the following command:
```
$ oc apply -f workload-config.yaml
```

Extract the admin-kubeconfig secret by entering the following command:

$ oc extract -n <hosted_cluster_namespace> \
  secret/<hosted_cluster_name>-admin-kubeconfig \
  --to=./hostedcluster-secrets --confirm

Example output

hostedcluster-secrets/kubeconfig

You can check if new nodes are in the Ready status by entering the following command:
```
$ oc --kubeconfig ./hostedcluster-secrets get nodes
```

To remove the node, delete the workload by entering the following command:

$ oc --kubeconfig ./hostedcluster-secrets -n <namespace> \
  delete deployment <deployment_name>

Wait for several minutes to pass without requiring the additional capacity. On the Agent platform, the agent is decommissioned and can be reused. You can confirm that the node was removed by entering the following command:

$ oc --kubeconfig ./hostedcluster-secrets get nodes

For IBM Z® agents, if you are using an OSA network device in Processor Resource/Systems Manager (PR/SM) mode, auto scaling is not supported. You must delete the old agent manually and scale up the node pool because the new agent joins during the scale down process.