Release channels

Managed Service for Kubernetes provides updates through release channels.

The service supports three Kubernetes release channels. Master node and Managed Service for Kubernetes node group versions are independent; therefore, you can specify different Kubernetes versions from a single release channel when creating them.

When creating a Managed Service for Kubernetes cluster, specify one of the three release channels. You cannot change the channel after the Managed Service for Kubernetes cluster is created, you can only recreate the cluster and specify a new release channel. The table below describes the release channels and contains up-to-date information about the supported Kubernetes versions.

Channel	Kubernetes versions	Automatic updates	Channel description
rapid	1.29, 1.30, 1.31	Automatic updates cannot be disabled. You can specify a time period for automatic updates.	Updates with new features and improvements are added to the channel first.
regular	1.29, 1.30, 1.31	Automatic updates can be disabled.	New features and improvements are added shortly after they appear on rapid.
stable	1.29, 1.30	Automatic updates can be disabled.	New features and improvements are added shortly after they appear on regular.

UpdatesUpdates

When an update appears on a release channel, the corresponding information is displayed in the management console. You can install updates automatically or manually.

• Automatic updates are installed in the specified period of time with no user interaction.

  Updates are triggered and should be completed within the specified period. In some cases, when updating a Managed Service for Kubernetes node group, an update may continue beyond this period.

  Automatic updates include new Managed Service for Kubernetes functions, improvements, and fixes, as well as Kubernetes component fixes.

• Manual updates can be initiated by the user at any time.

  They include Kubernetes minor version updates.

Read more about Kubernetes version support termination and the Managed Service for Kubernetes cluster component update process.

Kubernetes version support terminationKubernetes version support termination

When upgrading from a deprecated Kubernetes version:

• The Managed Service for Kubernetes master cannot be updated automatically, update it manually.
• Minor versions (e.g., from 1.20 to 1.21) must be updated manually.
• Managed Service for Kubernetes node groups update automatically if automatic updates are enabled. If automatic updates are disabled, the old version of Kubernetes remains on the Managed Service for Kubernetes node groups. In this case, the user is fully responsible for solving problems related to the Managed Service for Kubernetes node group, since the old version of Kubernetes is deprecated.

Updating Kubernetes cluster componentsUpdating Kubernetes cluster components

The update process is different for a Managed Service for Kubernetes master and node groups.

MasterMaster

The amount of time a Managed Service for Kubernetes master is unavailable during an update depends on the master type:

• The basic master is unavailable during the update.
• The highly available master maintains connectivity during the update.

For more information, see Updating a cluster.

Node groupNode group

You can update a Managed Service for Kubernetes node group with additional resources allocated by creating nodes with a new configuration.

The Managed Service for Kubernetes node group update algorithm is as follows:

1. An updated node is created with the configuration specified for the entire Managed Service for Kubernetes node group.
2. All the pods are evicted from one of the old Managed Service for Kubernetes nodes based on the pre-defined PodDisruptionBudgets policy. Then the node is deleted.
3. The process is repeated until all the Managed Service for Kubernetes nodes in the group are updated.

This ensures that the number of nodes in the group never falls below the number specified when the Managed Service for Kubernetes node group is created.

You can specify the maximum number of VM instances by which you can expand or reduce the size of the Managed Service for Kubernetes group when updating it. For more information, see Updating a node group.

CertificatesCertificates

In accordance with the safety recommendations, Managed Service for Kubernetes cluster and node group certificates are valid for one year. When a certificate expires, a Managed Service for Kubernetes cluster or node group will be disabled. To avoid this, Managed Service for Kubernetes automatically updates their certificates.

• If automatic updates are enabled, certificates are updated automatically whenever a Managed Service for Kubernetes cluster or node group updates.
• If automatic updates are disabled, a certificate update will be forced a week before they expire.

For more information about updating certificates, see the Kubernetes documentation.