How to Manage Nodes and Node Pools with the OVHcloud API

Objective

OVHcloud Managed Kubernetes service provides you Kubernetes clusters without the hassle of installing or operating them. This guide will cover one of the first steps after ordering a cluster: managing nodes and node pools, using the OVHcloud API.

In this guide, we are assuming you’re using the OVHcloud API to manage your Kubernetes cluster. If you are using a different method, like the OVHcloud Manager, please refer to the relevant documentation: Managing nodes and node pools guide.

Requirements

• An OVHcloud Managed Kubernetes cluster

Nodes and node pools

In your OVHcloud Managed Kubernetes cluster, nodes are grouped in node pools (group of nodes sharing the same configuration).

When you create your cluster, it’s created with a default node pool. Then, you can modify the size of this node pool, or add additional node pools of different sizes and types.

Upon creation, node pool is defined by its name (name), the type of instance within our available catalog (flavorName), the number of identical nodes that you want in that node pool (desiredNodes), and potentially self-defined boundaries to limit the value of desired nodes (minNodes and maxNodes). Setting the antiAffinity boolean ensures that nodes in that node pool will be created on different hypervisors (baremetal machines) and therefore ensure the best availability for your workload. The maximum number of nodes is set to 5 if this feature is activated on a nodepool (you can of course create multiple node pools with each 5 anti-affinity nodes max). Finally monthlyBilled boolean ensures that all nodes in a node pool will be spawned in monthly billing mode and therefore benefit from the monthly discount.

After creation, the desiredNodes can be edited, and the node pool will automatically be resized to accommodate this new value. minNodes and maxNodes can also be edited at any time.

We will later propose cluster autoscaling based on node pols. We see some customer developing they own autoscaling scripts. We strongly encourage you to define minNodes and maxNodes in that case.

In this guide we explain how to do some basic operations with nodes and node pools using the OVHcloud API: adding nodes to an existing node pool, creating a new node pool…

Upsizing and downsizing a Node Pool

By editing the desiredNodes value to a value different from currentNodes one (for values between the minNodes and maxNodes), i will trigger the node pool upsizing or downsizing.

When downsizing, the last created node will be drained then deleted first, then the before last created is drain and deleted, and this process is reproduced until the “current nodes” is equal to desiredNodes.

When upsizing, a first node is created and when it is ready, another is created, and this process is reproduced until the currentNodes is equal to desiredNodes.

The API Explorer

To simplify things, we are using the API Explorer, which allows to explore, learn and interact with the API in an interactive way.

Log in to the API Explorer using your OVH NIC.

If you go to the Cloud section of the API Explorer, you will see follwoing available endpoint:

/cloud/project/{serviceName}/kube

List your OVHcloud Managed Kubernetes clusters

The GET /cloud/project API endpoint lists all the available Public Cloud Services associated to your OVHcloud account:

Choose the Public Cloud Service corresponding to your OVHcloud Managed Kubernetes. In this example, we will refer to it as serviceName

The GET /cloud/project/{serviceName}/kube API endpoint lists all the available clusters in your chosen project:

By calling it, you can view a list of your Kubernetes clusters ID. Note down the ID of the cluster you want to use. In this example, we will refer to it as kubeId

Getting your cluster information

The GET /cloud/project/{serviceName}/kube/{kubeId} API endpoint provides important information about your OVHcloud Managed Kubernetes cluster, including its status and URL.

Listing node pools

The GET /cloud/project/{serviceName}/kube/{kubeId}/nodepool API endpoint lists all the available node pools:

Create a node pool

Use the PUT /cloud/project/{serviceName}/kube/{kubeId}/nodepool API endpoint to create a new node pool:

You will need to give it a flavorName parameter, with the flavor of the instance you want to create. For this tutorial choose a general purpose node, like the b2-7 flavor.

If you want your node pool to have at least one node, set the desiredNodes to a value above 0.

The API will return you the new node pool information.

Get information on a node pool

To get information on a specific node pool, use the following API endpoint:

GET /cloud/project/{serviceName}/kube/{kubeId}/nodepool/{nodePoolId}

Editing the node pool size

To upsize or downsize your node pool, you can use the following API endpoint:

PUT /cloud/project/{serviceName}/kube/{kubeId}/nodepool/{nodePoolId}

and set the desiredNodes to the new pool size (between minNodes and maxNodes, that you can modify if needed).

Deleting a node pool

To delete a node pool, use the following API endpoint:

DELETE /cloud/project/{serviceName}/kube/{kubeId}/nodepool/{nodePoolId}

Go further

For an overview of OVHcloud Managed Kubernetes service, you can go to the OVHcloud Managed Kubernetes site.

Otherwise to skip it and push to deploy your first application on your Kubernetes cluster, we invite you to follow our guide to configuring default settings for kubectl and deploying an application .