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EMK - Cluster high availability

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This page describes how to set up high availability for your Kubernetes cluster. It will also describe how those settings are configured in the YAML structure.

There are two high availability (HA) options:

  • zone
  • node (YAML option only)

Configuring HA requires the following characteristics:

  • Worker pool should have a minimum of 3 nodes.
  • Worker pool settings for at least 3 zones.
  • A multi-node etcd (quorum size of 3) will be provisioned, offering zero-downtime capabilities with each member in a different zone.

Allowed Transitions

If you already have a shoot cluster with non-HA control plane, then the following upgrades are possible:

  • Upgrade of non-HA shoot control plane to HA shoot control plane with failure tolerance.

Downtime

There will be a short downtime during the upgrade, especially for etcd, which will transition from a single node etcd cluster to a multi-node etcd cluster.

Disallowed Transitions

If you already have a shoot cluster with HA control plane:

  • Disabling high availability.
  • Changing the failure tolerance.

Enabling high availability on an EMK Cluster is straightforward.

Navigate to the EMK Cluster overview in the Fuga dashboard

Cluster overview

Click on the cluster you want to enable HA on.

Hibernation schedules

Navigate to the Infrastructure and click on Control Plane High Availability.

spec:
  controlPlane:
    highAvailability:
      failureTolerance:
        type: <node | zone>