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Chapter 1. Preparing to install on a single node
1.1. Prerequisites
- You reviewed details about the OpenShift Container Platform installation and update processes.
- You have read the documentation on selecting a cluster installation method and preparing it for users.
1.2. About OpenShift on a single node
You can create a single-node cluster with standard installation methods. OpenShift Container Platform on a single node is a specialized installation that requires the creation of a special ignition configuration ISO. The primary use case is for edge computing workloads, including intermittent connectivity, portable clouds, and 5G radio access networks (RAN) close to a base station. The major tradeoff with an installation on a single node is the lack of high availability.
The use of OpenShiftSDN with single-node OpenShift is not supported. OVN-Kubernetes is the default network plugin for single-node OpenShift deployments.
1.3. Requirements for installing OpenShift on a single node
Installing OpenShift Container Platform on a single node alleviates some of the requirements for high availability and large scale clusters. However, you must address the following requirements:
- Administration host: You must have a computer to prepare the ISO, to create the USB boot drive, and to monitor the installation.
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Supported platforms: Installing OpenShift Container Platform on a single node is supported on bare metal and Certified third-party hypervisors. In all cases, you must specify the
platform.none: {}parameter in theinstall-config.yamlconfiguration file. Production-grade server: Installing OpenShift Container Platform on a single node requires a server with sufficient resources to run OpenShift Container Platform services and a production workload.
Table 1.1. Minimum resource requirements Profile vCPU Memory Storage Minimum
8 vCPUs
16GB of RAM
120GB
NoteOne vCPU equals one physical core. However, if you enable simultaneous multithreading (SMT), or Hyper-Threading, use the following formula to calculate the number of vCPUs that represent one physical core:
- (threads per core × cores) × sockets = vCPUs
- Adding Operators during the installation process might increase the minimum resource requirements.
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 1.2. 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.
Internal API
api-int.<cluster_name>.<base_domain>Add a DNS A/AAAA or CNAME record when creating the ISO manually. This record must be resolvable by nodes within 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.
Without persistent IP addresses, communications between the
apiserverandetcdmight fail.
