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Installing a cluster on user-provisioned infrastructure in AWS by using CloudFormation templates

In OpenShift Container Platform version 4.11, you can install a cluster on Amazon Web Services (AWS) that uses infrastructure that you provide.

One way to create this infrastructure is to use the provided CloudFormation templates. You can modify the templates to customize your infrastructure or use the information that they contain to create AWS objects according to your company’s policies.

The steps for performing a user-provisioned infrastructure installation are provided as an example only. Installing a cluster with infrastructure you provide requires knowledge of the cloud provider and the installation process of OpenShift Container Platform. Several CloudFormation templates are provided to assist in completing these steps or to help model your own. You are also free to create the required resources through other methods; the templates are just an example.

Prerequisites

Internet access for OpenShift Container Platform

In OpenShift Container Platform 4.11, you require access to the internet to install your cluster.

You must have internet access to:

  • Access OpenShift Cluster Manager Hybrid Cloud Console to download the installation program and perform subscription management. If the cluster has internet access and you do not disable Telemetry, that service automatically entitles your cluster.

  • Access Quay.io to obtain the packages that are required to install your cluster.

  • Obtain the packages that are required to perform cluster updates.

If your cluster cannot have direct internet access, you can perform a restricted network installation on some types of infrastructure that you provision. During that process, you download the required content and use it to populate a mirror registry with the installation packages. With some installation types, the environment that you install your cluster in will not require internet access. Before you update the cluster, you update the content of the mirror registry.

Requirements for a cluster with user-provisioned infrastructure

For a cluster that contains user-provisioned infrastructure, you must deploy all of the required machines.

This section describes the requirements for deploying OpenShift Container Platform on user-provisioned infrastructure.

Required machines for cluster installation

The smallest OpenShift Container Platform clusters require the following hosts:

Table 1. Minimum required hosts
Hosts Description

One temporary bootstrap machine

The cluster requires the bootstrap machine to deploy the OpenShift Container Platform cluster on the three control plane machines. You can remove the bootstrap machine after you install the cluster.

Three control plane machines

The control plane machines run the Kubernetes and OpenShift Container Platform services that form the control plane.

At least two compute machines, which are also known as worker machines.

The workloads requested by OpenShift Container Platform users run on the compute machines.

To maintain high availability of your cluster, use separate physical hosts for these cluster machines.

The bootstrap and control plane machines must use Red Hat Enterprise Linux CoreOS (RHCOS) as the operating system. However, the compute machines can choose between Red Hat Enterprise Linux CoreOS (RHCOS), Red Hat Enterprise Linux (RHEL) 8.4, or RHEL 8.5.

Note that RHCOS is based on Red Hat Enterprise Linux (RHEL) 8 and inherits all of its hardware certifications and requirements. See Red Hat Enterprise Linux technology capabilities and limits.

Minimum resource requirements for cluster installation

Each cluster machine must meet the following minimum requirements:

Table 2. Minimum resource requirements
Machine Operating System vCPU [1] Virtual RAM Storage IOPS [2]

Bootstrap

RHCOS

4

16 GB

100 GB

300

Control plane

RHCOS

4

16 GB

100 GB

300

Compute

RHCOS, RHEL 8.4, or RHEL 8.5 [3]

2

8 GB

100 GB

300

  1. One vCPU is equivalent to one physical core when simultaneous multithreading (SMT), or hyperthreading, is not enabled. When enabled, use the following formula to calculate the corresponding ratio: (threads per core × cores) × sockets = vCPUs.

  2. OpenShift Container Platform and Kubernetes are sensitive to disk performance, and faster storage is recommended, particularly for etcd on the control plane nodes which require a 10 ms p99 fsync duration. Note that on many cloud platforms, storage size and IOPS scale together, so you might need to over-allocate storage volume to obtain sufficient performance.

  3. As with all user-provisioned installations, if you choose to use RHEL compute machines in your cluster, you take responsibility for all operating system life cycle management and maintenance, including performing system updates, applying patches, and completing all other required tasks. Use of RHEL 7 compute machines is deprecated and has been removed in OpenShift Container Platform 4.10 and later.

If an instance type for your platform meets the minimum requirements for cluster machines, it is supported to use in OpenShift Container Platform.

Tested instance types for AWS

The following Amazon Web Services (AWS) instance types have been tested with OpenShift Container Platform.

Use the machine types included in the following charts for your AWS instances. If you use an instance type that is not listed in the chart, ensure that the instance size you use matches the minimum resource requirements that are listed in "Minimum resource requirements for cluster installation".
Machine types based on x86_64 architecture

  • c4.*

  • c5.*

  • c5a.*

  • i3.*

  • m4.*

  • m5.*

  • m5a.*

  • m6i.*

  • r4.*

  • r5.*

  • r5a.*

  • r6i.*

  • t3.*

  • t3a.*

Tested instance types for AWS ARM

The following Amazon Web Services (AWS) ARM instance types have been tested with OpenShift Container Platform.

Use the machine types included in the following charts for your AWS ARM instances. If you use an instance type that is not listed in the chart, ensure that the instance size you use matches the minimum resource requirements that are listed in "Minimum resource requirements for cluster installation".
Machine types based on arm64 architecture

  • c6g.*

  • m6g.*

Certificate signing requests management

Because your cluster has limited access to automatic machine management when you use infrastructure that you provision, you must provide a mechanism for approving cluster certificate signing requests (CSRs) after installation. The kube-controller-manager only approves the kubelet client CSRs. The machine-approver cannot guarantee the validity of a serving certificate that is requested by using kubelet credentials because it cannot confirm that the correct machine issued the request. You must determine and implement a method of verifying the validity of the kubelet serving certificate requests and approving them.

Supported AWS machine types

The following Amazon Web Services (AWS) instance types are supported with OpenShift Container Platform.

Machine types based on x86_64 architecture
Instance type Bootstrap Control plane Compute

i3.large

x

m4.large

x

m4.xlarge

x

x

m4.2xlarge