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 are using the OVHcloud API to manage your Kubernetes cluster. If you are using a different method, like the OVHcloud Control Panel, 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).
In the cluster creation call, you can specify the specs of a first node pool that will be created with it. Then, you can update this node pool or add additional node pools of different sizes and types.
Upon creation, a 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).
You can also enable the autoscale feature, and the desiredNodes will be automatically updated at runtime within the minNodes and maxNodes boundaries, depending on the resource reservations of your workload (see Using the cluster autoscaler).
Setting the antiAffinity boolean ensures that nodes in that node pool will be created on different hypervisors (baremetal machines), ensuring the best availability for your workload. The maximum number of nodes is set to five if this feature is activated on a node pool (you can of course create multiple node pools each of which will have five anti-affinity nodes max).
Setting the template property will allow you to define some specs (annotations, finalizers, labels, taints, schedule) that will be applied to each node under this node pool.
Finally, the 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, minNodes, maxNodes, autoscale, and template properties can also be edited at anytime.
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, etc.
Upsizing and downsizing a Node Pool
Editing the desiredNodes property to a different value will trigger the node pool upsizing or downsizing.
When downsizing, the last created nodes will be drained and then deleted in parallel. You can also specify which nodes should be removed by filling in the optional nodesToRemove property, which can be a list of node names, node IDs, or OpenStack instance IDs.
When upsizing, all new nodes will be created in parallel.
The API Explorer
To simplify things, we are using the API Explorer, which allows us to explore, learn, and interact with the API in an interactive way.
Log into the API Explorer using your OVHcloud credentials.
Now proceed through the login screens. If you go to the Cloud section of the API Explorer, you will see the available /cloud/project/{serviceName}/kube endpoint.
List your OVHcloud Managed Kubernetes clusters
The GET /cloud/project API endpoint lists all the available Public Cloud Services associated with your OVHcloud account:
Choose the Public Cloud Service corresponding to your OVHcloud Managed Kubernetes project. 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:
Using this call, you can view a list of your Kubernetes cluster IDs. 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 of the available node pools:
Create a nodepool
Use the POST /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 the new node pool information.
Get information on a node pool
Use the GET /cloud/project/{serviceName}/kube/{kubeId}/nodepool/{nodePoolId} API endpoint to get information on a specific node pool:
Updating the node pool
To upsize or downsize your node pool, you can use the PUT /cloud/project/{serviceName}/kube/{kubeId}/nodepool/{nodePoolId} API endpoint, and set the desiredNodes to the new pool size. You can also modify some other properties:
Deleting a node pool
To delete a node pool, use the /DELETE /cloud/project/{serviceName}/kube/{kubeId}/nodepool/{nodePoolId} API endpoint:
Go further
For an overview of OVHcloud Managed Kubernetes service, you can go to the OVHcloud Managed Kubernetes page.
Otherwise, 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.