About installing on a single node

An installation of OKD on a single node is a specialized installation. The primary use case is for edge computing workloads, including small physical footprints, intermittent connectivity, portable clouds, and 5G radio access networks (RAN) close to a base station. An installation on a single node supports autonomous workloads.

The major trade off with an installation on a single node is the lack of high availability. Currently, Red Hat does not support upgrading OKD when installed on a single node. Upgrades and some configuration changes require re-installation.

Requirements for installing on a single node

Installing OKD on a single node alleviates some of the requirements of high availability and large scale clusters. However, you must address the following requirements:

  • Administration node: You must have an administration node or laptop to access Install OpenShift with the Assisted Installer, to specify the cluster name, to create the USB boot drive, and to monitor the installation.

  • Production-grade server: Installing OKD on a single node requires a server with sufficient resources to run OKD services and a production workload.

    Table 1. Hardware requirements
    Profile CPU Memory Storage

    Minimum

    8 CPU cores

    32GB of RAM

    120GB

    The server must have a Baseboard Management Controller (BMC) when booting with virtual media.

  • Networking: The server must have access to the internet or access to a local registry if it is not connected to a routable network. The server must have a DHCP reservation or a static IP address for the Kubernetes API, Ingress route, and cluster node domain names. You must configure the DNS to resolve the IP address to each of the following fully qualified domain names (FQDN):

    Table 2. Required DNS records
    Usage FQDN Description

    Kubernetes API

    api.<cluster_name>.<base_domain>

    Add a DNS A/AAAA or CNAME record. This record must be resolvable by clients external to the cluster.

    Ingress route

    *.apps.<cluster_name>.<base_domain>

    Add a wildcard DNS A/AAAA or CNAME record that targets the node. This record must be resolvable by clients external to the cluster.

    Cluster node

    <hostname>.<cluster_name>.<base_domain>

    Add a DNS A/AAAA or CNAME record and DNS PTR record to identify the node.

    Without persistent IP addresses, communications between the apiserver and etcd might fail.