Overview

Exoscale’s Scalable Kubernetes Service (SKS) is a fully managed Kubernetes offering designed to simplify the deployment, scaling, and management of containerized applications. SKS provides a production-ready control plane, seamless integration with Exoscale infrastructure, and supports the full Kubernetes ecosystem.

Terminology

• Cluster
  A virtual entity encapsulating a Kubernetes control plane and one or more node pools.
• Control Plane
  The set of components that manage the lifecycle of a Kubernetes cluster, including the API server, scheduler, and controller manager.
• Instance Pool
  A group of similar Compute instances whose lifecycle is managed by the scheduler, created upon a set of user-specified instance properties (such as size, template, security groups, et cetera).
• Node Pool
  A group of compute instances managed by SKS, serving as worker nodes in your Kubernetes cluster.
• Node
  A compute instance within a node pool that runs Kubernetes workloads.

Features

Scalable Kubernetes Service has an expansive feature set:

• Managed Control Plane
  SKS delivers a fully managed, highly available Kubernetes control plane, eliminating the need for manual setup and maintenance.
• Dynamic Node Pools
  Easily scale your workloads by adding or removing node pools, which are groups of compute instances managed by SKS.
• Full Cluster Lifecycle Management
  Create, upgrade, and delete clusters on demand. SKS supports automatic upgrades to the latest Kubernetes patch versions.
• Seamless Integration with Exoscale Services
  Leverage Exoscale’s Network Load Balancer, Block Storage via CSI driver, and other services directly within your SKS clusters.
• Customizable Node Pools
  Use any Exoscale instance type within your node pools, including CPU-optimized, memory-optimized, and GPU instances.
• High Availability (Pro Plan)
  The Pro Cluster Plan offers a resilient, highly available control plane to ensure your workloads remain operational and plus automatic scalability of control plane resources.
• CNCF Certified
  SKS is certified by the Cloud Native Computing Foundation, ensuring compatibility and support for standard Kubernetes APIs.

Architecture

Following is a breakdown of the overall SKS architecture.

Pricing Tiers

Exoscale offers SKS in two tiers: Starter and Pro, each tailored to different use cases

NOTE
Starter clusters without attached node pools will be deleted after 30 days of inactivity.

Control Plane

Exoscale runs the Kubernetes control plane for you—including the API Server, Controller Manager, Scheduler, and Konnectivity Server—ensuring high availability (in Pro plans), security, and minimal operational overhead. You don’t manage or access the control plane directly.

You deploy several components when you create a cluster. Some run on the Exoscale side, and some run on your cluster.

Control Plane Components (Exoscale-managed)

• The Kubernetes API Server.
• The Kubernetes Controller Manager.
• The Kubernetes Scheduler.
• The Konnectivity Server, which is used to provide a TCP level proxy for the control plane to cluster communication.
• The Exoscale Cloud Controller Manager also comes as a default.

In-Cluster Components (Deployed Automatically)

• Kube Proxy to forward the traffic to pods (using the iptables mode).
• CoreDNS to manage the cluster DNS. The CoreDNS ConfigMap (named coredns in the kube-system namespace) is never updated by Exoscale after the first deployment so you can override it if needed.
• The Konnectivity agent is also deployed on the cluster.
• Calico is deployed by default to manage the cluster network. You can also choose to deploy a cluster without CNI plugins.
• Metrics server is also deployed by default. You can use it to gather pods and nodes metrics, and auto-scale your deployments.

Additional Features

• Rapid cluster provisioning (≈2 minutes)

• Automated or manual Kubernetes upgrades

• Private networking and NLB support

• CLI, API, Terraform, Pulumi, and web UI integration

• OIDC integration for secure RBAC access

Node Pools

A node pool is a logical group of Kubernetes workers. When you create a node pool, you specify:

• the characteristics for the workers (instance disk size, instance type, firewall or anti-affinity rules, …)
• the number of workers

The worker instances (or virtual machines) will be provisioned and will join the cluster automatically.

A cluster can have multiple node pools, each with its own characteristics depending of what you need.

Node pools are backed by Instance Pools. When a node pool is created, a new instance pool named nodepool-<nodepool-name>-<nodepool-id> is also created.

NOTE
You cannot interact with this Instance Pool directly. It will be managed completely by Exoscale depending on the node pool state. If you want to scale your node pool, or evict machines from it, you need to target the node pool, not the Instance Pool. A node pool with an anti-affinity group can not contain more than 8 nodes.

Exoscale Cloud Controller Manager

The Exoscale Cloud Controller Manager performs several actions on the cluster:

• Validates nodes. When a node joins the cluster, the controller will enable it and approve the Kubelet server certificate signing request.
• Manages load balancers. The controller will automatically provision and manage Exoscale Network Load balancers based on Kubernetes services of the type LoadBalancer for a highly available load balancing setup for your cluster.

When the Exoscale Cloud Controller is enabled, an IAM key is automatically provisioned on your account. You can find more information about this Cloud Controller IAM key (and how to rotate it) in the SKS Certificates and Keys section.

Service Level and Support

Exoscale’s Scalable Kubernetes Service (SKS) offers a fully managed control plane with defined service levels and support scopes.

Control Plane SLA

In the Pro service tier, the following Kubernetes control plane components are covered by a 99.95% Service Level Agreement (SLA):

• etcd
• kube-apiserver
• kube-scheduler
• kube-controller-manager
• Exoscale Cloud Controller Manager (CCM)

This ensures high availability and reliability for the core components managing your cluster’s state and operations.

Node-Level SLA

While the control plane is managed by Exoscale, the worker nodes within your SKS cluster are your responsibility. Each node is subject to Exoscale’s standard compute SLA of 99.95%, ensuring consistent performance and uptime for your workloads.

In-Cluster Components

Exoscale deploys several essential components within your SKS clusters to facilitate networking, service discovery, and storage integration:

• Container Network Interface (CNI) plugins: Calico or Cilium
• CoreDNS
• Konnectivity
• kube-proxy
• Container Storage Interface (CSI) driver

These components are not covered by the SKS SLA due to the shared responsibility model. However, Exoscale provides best-effort support, including upgrade tools and operational guidance. In certain scenarios, support may request temporary access to your cluster’s kubeconfig to assist with troubleshooting.

Best Practices for Stability

To ensure optimal performance and supportability of your SKS cluster:

• Resource Management Set appropriate resource requests and limits for all workloads. This practice helps prevent resource contention and ensures fair scheduling across the cluster.

• Monitoring Node Health Regularly monitor the health status of your nodes. If nodes are reported as “NotReady” or if core components exhibit unexpected behavior, verifying resource configurations can aid in diagnosis.

Following these best practices helps maintain cluster stability and simplifies troubleshooting, enabling faster and more effective support when needed.

Availability

The SKS offering is currently available in the following zones:

Limitations

SKS is available with the following limitations to ensure performance and supportability:

• NodePort Range The number of SKS clusters per zone is currently limited by the available NodePort range (default 30000-32767).
• Persistent Volume Attachments Volumes can be attached to only one node at a time. Online resizing of PersistentVolumes is not supported.
• CSI Add-on Availability The CSI driver for block storage is only available in zones where Block Storage is supported.
• Minimun instances size and disk size Minimum instance size is Small or 2 GB RAM equivalent and minimum instance disk size is 20 GB.
• No cross-zone stretch support Each cluster is local to a single zone only.
• Root Credential Expiry Root API credentials (including tokens used by cluster automation tools) have a maximum time-to-live (TTL) of 30 days. After that, they expire and must be rotated or renewed to maintain access.

See Also

Take a look at the free online academy courses:

• SKS STARTER
• SKS ADVANCED