Enabling high availability

When you create a new Gardener cluster, you have the option to enable high availability (HA) features for its control plane. In case you have an existing Gardener cluster with a non-HA control plane, you may at any time enable the HA features for that control plane.

Keep in mind that once you enable HA for the control plane of a Gardener cluster, you cannot disable it for that particular cluster.

Additionally, you may add HA characteristics to one or more Worker Groups of an existing cluster.

Enabling HA for the control plane

Using your favorite web browser, navigate to https://cleura.cloud and log in. In the left-hand side panel, choose Containers → Gardener. Then, in the central pane of the Cleura Cloud Management Panel, you see all of your Gardener clusters, organized by Cleura Cloud region.

Locate the cluster you are interested in, and click the orange icon on the right of the corresponding row. From the drop-down menu that appears, select Modify Cluster.

A vertical pane titled Modify Gardener Shoot Cluster slides over from the right. In it, you see the disabled option Enable Highly Available Control Plane. Click on it to enable HA for the control plane of the shoot cluster.

Before the change is applied, a warning appears: enabling HA is an irreversible action. Once you take it, there is no way to disable HA at a later time.

If you are sure you want to enable HA, scroll down a bit until you see the green Update button and click on it.

Enabling HA for the control plane of any Gardener cluster takes a few minutes. You can see how the process is progressing by the animated icon on the left of the cluster row.

As soon as HA is enabled, the animated icon changes into a check mark ().

Enabling HA for Worker Groups

You may add HA characteristics to one or more Worker Groups by modifying the Autoscaler Min and Autoscaler Max parameters.

First off, select the Gardener cluster you are interested in. Click on the cluster row to expand its characteristics, then select the Worker Groups tab.

Click once more on the icon of the Worker Group you wish to modify. A vertical pane named Modify Worker Group slides over from the right.

Modify the Autoscaler Min and Autoscaler Max parameters. You may, for instance, set Autoscaler Min to 3 and Autoscaler Max to 5. When you are ready to apply the changes, click the green Update button.

After a few seconds, the new values for the autoscaler parameters will be visible in the Worker Groups tab.

Having Worker Groups in different Availability Zones

Another way to make Worker Groups highly available is to have at least two such groups, each in its own Availability Zone (AZ).

To create a new Worker Group in its own AZ, begin by locating the cluster you are interested in, then click its row to have all relevant details in full view. Click once more on the Worker Groups tab to see all available groups. In the example below, there is only one Worker Group that resides in the AZ named az1. To create a new Worker Group, click on the green Create a Worker Group button.

A vertical pane named Create Worker Group slides over from the right. There, you see the parameters of a new group. Before you create it, click on the drop-down menu for Availability Zones, and indicate an AZ for the new group. Make sure you pick one which is different from the AZ where the first Worker Group resides.

Optionally, you can have the new Worker Group reside only in the new AZ you just selected: for that, click the old AZ label to remove it. Finally, click on the green Create button to instantiate the new WG.

When the new Worker Group is ready, you can see all groups in the Worker Groups tab, each in its own AZ.