---
title: Installing a three-node cluster on OpenStack
---

# Installing a three-node cluster on OpenStack {#installing-openstack-three-node}

In OpenShift Container Platform version 4.22, you can install a three-node cluster on Red Hat OpenStack Platform (RHOSP). A three-node cluster consists of three control plane machines, which also act as compute machines.

This type of cluster provides a smaller, more resource efficient cluster, for cluster administrators and developers to use for testing, development, and production.

You can install a three-node cluster on installer-provisioned infrastructure only. After you install a three-node cluster on RHOSP, you can apply customizations to the cluster. For more information, see "Installing a cluster on RHOSP with customizations".

## Configuring a three-node cluster {#installation-three-node-cluster_installing-openstack-three-node}

To configure a three-node cluster, set the number of worker nodes to `0` in the `install-config.yaml` file before you deploy the cluster.

Setting the number of worker nodes to `0` ensures that the control plane machines are schedulable. This allows application workloads to be scheduled to run from the control plane nodes.

> [!NOTE]
> Because application workloads run from control plane nodes, additional subscriptions are required, as the control plane nodes are considered to be compute nodes.

**Prerequisites**

- You have an existing `install-config.yaml` file.

**Procedure**

- Set the number of compute replicas to `0` in your `install-config.yaml` file, as shown in the following `compute` stanza:

.Example `install-config.yaml` file for a three-node cluster

```yaml
apiVersion: v1
baseDomain: example.com
compute:
- name: worker
  platform: {}
  replicas: 0
# ...
```

**Additional resources**
{._additional-resources}

- [Installing a cluster on RHOSP with customizations](/openshift-docs-markdown/installing/installing_openstack/installing-openstack-installer-custom#installing-openstack-installer-custom)