Placement Groups

Hetzner Cloud Placement Groups allow you to control how your Kubernetes nodes are distributed across physical hosts within Hetzner’s infrastructure. By assigning nodes to a placement group of type spread, you ensure that each node is scheduled on a different physical machine, increasing fault tolerance and availability.

This feature is especially useful for high-availability Kubernetes clusters, as it minimizes the risk of multiple nodes failing due to hardware issues on a single host.

Creating placement groups

In the Cluster resource, you can create placement groups in the spec.topology.variables section. The following example creates two placement groups:

yaml

- name: hcloudPlacementGroups value: - name: myPlacementGroup1 type: spread - name: myPlacementGroup2 type: spread

note

As of now, Hetzner Cloud only supports the spread placement group type. If you want to know more, you can read the Hetzner documentation.

Adding placement groups to machine deployments

To add placement groups to your machine deployments, you can set them in variables.overrides :

yaml

machineDeployments: - class: workeramd64hcloud name: md-0 replicas: 5 failureDomain: nbg1 variables: overrides: - name: workerMachineTypeHcloud value: cpx31 - name: workerMachinePlacementGroupNameHcloud value: myPlacementGroup1

The name should match an existing placement group, created in your Cluster resource topology.variables :

Adding placement groups to controlplane nodes

You can set control plane placement groups in spec.topology.variables :

yaml

- name: controlPlanePlacementGroupNameHcloud value: myPlacementGroup2

Here is an example of a complete Cluster resource with placement groups:

cluster.yaml yaml

apiVersion: cluster.x-k8s.io/v1beta1 kind: Cluster metadata: name: mycluster spec: clusterNetwork: services: cidrBlocks: ['10.128.0.0/12'] pods: cidrBlocks: ['192.168.0.0/16'] serviceDomain: 'cluster.local' topology: class: hetzner-apalla-1-32-v1 version: v1.32.4 controlPlane: replicas: 3 variables: - name: hcloudPlacementGroups value: - name: myPlacementGroup1 type: spread - name: myPlacementGroup2 type: spread - name: controlPlanePlacementGroupNameHcloud value: myPlacementGroup2 workers: machineDeployments: - class: workeramd64hcloud name: md-0 replicas: 5 failureDomain: nbg1 variables: overrides: - name: workerMachineTypeHcloud value: cpx31 - name: workerMachinePlacementGroupNameHcloud value: myPlacementGroup1