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Installing a cluster on Azure using ARM templates

In OpenShift Container Platform version 4.10, you can install a cluster on Microsoft Azure by using infrastructure that you provide.

Several Azure Resource Manager (ARM) templates are provided to assist in completing these steps or to help model your own.

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 ARM 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 4.10, you require access to the internet to install your cluster.

You must have internet access to:

  • Access OpenShift Cluster Manager 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.

Configuring your Azure project

Before you can install OpenShift Container Platform, you must configure an Azure project to host it.

All Azure resources that are available through public endpoints are subject to resource name restrictions, and you cannot create resources that use certain terms. For a list of terms that Azure restricts, see Resolve reserved resource name errors in the Azure documentation.

Azure account limits

The OpenShift Container Platform cluster uses a number of Microsoft Azure components, and the default Azure subscription and service limits, quotas, and constraints affect your ability to install OpenShift Container Platform clusters.

Default limits vary by offer category types, such as Free Trial and Pay-As-You-Go, and by series, such as Dv2, F, and G. For example, the default for Enterprise Agreement subscriptions is 350 cores.

Check the limits for your subscription type and if necessary, increase quota limits for your account before you install a default cluster on Azure.

The following table summarizes the Azure components whose limits can impact your ability to install and run OpenShift Container Platform clusters.

Component Number of components required by default Default Azure limit Description

vCPU

40

20 per region

A default cluster requires 40 vCPUs, so you must increase the account limit.

By default, each cluster creates the following instances:

  • One bootstrap machine, which is removed after installation

  • Three control plane machines

  • Three compute machines

Because the bootstrap machine uses Standard_D4s_v3 machines, which use 4 vCPUs, the control plane machines use Standard_D8s_v3 virtual machines, which use 8 vCPUs, and the worker machines use Standard_D4s_v3 virtual machines, which use 4 vCPUs, a default cluster requires 40 vCPUs. The bootstrap node VM, which uses 4 vCPUs, is used only during installation.

To deploy more worker nodes, enable autoscaling, deploy large workloads, or use a different instance type, you must further increase the vCPU limit for your account to ensure that your cluster can deploy the machines that you require.

By default, the installation program distributes control plane and compute machines across all availability zones within a region. To ensure high availability for your cluster, select a region with at least three availability zones. If your region contains fewer than three availability zones, the installation program places more than one control plane machine in the available zones.

OS Disk

7

VM OS disk must be able to sustain a tested and recommended minimum throughput of 5000 IOPS / 200MBps. This throughput can be provided by having a minimum of 1 TiB Premium SSD (P30). In Azure, disk performance is directly dependent on SSD disk sizes, so to achieve the throughput supported by Standard_D8s_v3, or other similar machine types available, and the target of 5000 IOPS, at least a P30 disk is required.

Host caching must be set to ReadOnly for low read latency and high read IOPS and throughput. The reads performed from the cache, which is present either in the VM memory or in the local SSD disk, are much faster than the reads from the data disk, which is in the blob storage.

VNet

1

1000 per region

Each default cluster requires one Virtual Network (VNet), which contains two subnets.

Network interfaces

7

65,536 per region

Each default cluster requires seven network interfaces. If you create more machines or your deployed workloads create load balancers, your cluster uses more network interfaces.

Network security groups

2

5000

Each cluster creates network security groups for each subnet in the VNet. The default cluster creates network security groups for the control plane and for the compute node subnets:

controlplane

Allows the control plane machines to be reached on port 6443 from anywhere
node

Allows worker nodes to be reached from the internet on ports 80 and 443

Network load balancers

3

1000 per region

Each cluster creates the following load balancers:

default

Public IP address that load balances requests to ports 80 and 443 across worker machines
internal

Private IP address that load balances requests to ports 6443 and 22623 across control plane machines
external

Public IP address that load balances requests to port 6443 across control plane machines

If your applications create more Kubernetes LoadBalancer service objects, your cluster uses more load balancers.

Public IP addresses

3

Each of the two public load balancers uses a public IP address. The bootstrap machine also uses a public IP address so that you can SSH into the machine to troubleshoot issues during installation. The IP address for the bootstrap node is used only during installation.

Private IP addresses

7

The internal load balancer, each of the three control plane machines, and each of the three worker machines each use a private IP address.

Spot VM vCPUs (optional)

0

If you configure spot VMs, your cluster must have two spot VM vCPUs for every compute node.

20 per region

This is an optional component. To use spot VMs, you must increase the Azure default limit to at least twice the number of compute nodes in your cluster.

Using spot VMs for control plane nodes is not recommended.

Configuring a public DNS zone in Azure

To install OpenShift Container Platform, the Microsoft Azure account you use must have a dedicated public hosted DNS zone in your account. This zone must be authoritative for the domain. This service provides cluster DNS resolution and name lookup for external connections to the cluster.

Procedure

  1. Identify your domain, or subdomain, and registrar. You can transfer an existing domain and registrar or obtain a new one through Azure or another source.

    For more information about purchasing domains through Azure, see Buy a custom domain name for Azure App Service in the Azure documentation.

  2. If you are using an existing domain and registrar, migrate its DNS to Azure. See Migrate an active DNS name to Azure App Service in the Azure documentation.

  3. Configure DNS for your domain. Follow the steps in the Tutorial: Host your domain in Azure DNS in the Azure documentation to create a public hosted zone for your domain or subdomain, extract the new authoritative name servers, and update the registrar records for the name servers that your domain uses.

    Use an appropriate root domain, such as openshiftcorp.com, or subdomain, such as clusters.openshiftcorp.com.

  4. If you use a subdomain, follow your company’s procedures to add its delegation records to the parent domain.

You can view Azure’s DNS solution by visiting this example for creating DNS zones.

Increasing Azure account limits

To increase an account limit, file a support request on the Azure portal.

You can increase only one type of quota per support request.
Procedure

  1. From the Azure portal, click Help + support in the lower left corner.

  2. Click New support request and then select the required values:

    1. From the Issue type list, select Service and subscription limits (quotas).

    2. From the Subscription list, select the subscription to modify.

    3. From the Quota type list, select the quota to increase. For example, select Compute-VM (cores-vCPUs) subscription limit increases to increase the number of vCPUs, which is required to install a cluster.

    4. Click Next: Solutions.

  3. On the Problem Details page, provide the required information for your quota increase:

    1. Click Provide details and provide the required details in the Quota details window.

    2. In the SUPPORT METHOD and CONTACT INFO sections, provide the issue severity and your contact details.

  4. Click Next: Review + create and then click Create.

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.

Required Azure roles

OpenShift Container Platform needs a service principal so it can manage Microsoft Azure resources. Before you can create a service principal, your Azure account subscription must have the following roles:

  • User Access Administrator

  • Owner

To set roles on the Azure portal, see the Manage access to Azure resources using RBAC and the Azure portal in the Azure documentation.

Creating a service principal

Because OpenShift Container Platform and its installation program create Microsoft Azure resources by using the Azure Resource Manager, you must create a service principal to represent it.

Prerequisites

  • Install or update the Azure CLI.

  • Your Azure account has the required roles for the subscription that you use.

Procedure

  1. Log in to the Azure CLI:

    $ az login

  2. If your Azure account uses subscriptions, ensure that you are using the right subscription:

    1. View the list of available accounts and record the tenantId value for the subscription you want to use for your cluster:

      $ az account list --refresh
      Example output
      [
  {
    "cloudName": "AzureCloud",
    "id": "9bab1460-96d5-40b3-a78e-17b15e978a80",
    "isDefault": true,
    "name": "Subscription Name",
    "state": "Enabled",
    "tenantId": "6057c7e9-b3ae-489d-a54e-de3f6bf6a8ee",
    "user": {
      "name": "you@example.com",
      "type": "user"
    }
  }
]

    2. View your active account details and confirm that the tenantId value matches the subscription you want to use:

      $ az account show
      Example output
      {
  "environmentName": "AzureCloud",
  "id": "9bab1460-96d5-40b3-a78e-17b15e978a80",
  "isDefault": true,
  "name": "Subscription Name",
  "state": "Enabled",
  "tenantId": "6057c7e9-b3ae-489d-a54e-de3f6bf6a8ee", (1)
  "user": {
    "name": "you@example.com",
    "type": "user"
  }
}
      1 Ensure that the value of the tenantId parameter is the correct subscription ID.

    3. If you are not using the right subscription, change the active subscription:

      $ az account set -s <subscription_id> (1)
      1 Specify the subscription ID.

    4. Verify the subscription ID update:

      $ az account show
      Example output
      {
  "environmentName": "AzureCloud",
  "id": "33212d16-bdf6-45cb-b038-f6565b61edda",
  "isDefault": true,
  "name": "Subscription Name",
  "state": "Enabled",
  "tenantId": "8049c7e9-c3de-762d-a54e-dc3f6be6a7ee",
  "user": {
    "name": "you@example.com",
    "type": "user"
  }
}

  3. Record the tenantId and id parameter values from the output. You need these values during the OpenShift Container Platform installation.

  4. Create the service principal for your account:

    $ az ad sp create-for-rbac --role Contributor --name <service_principal> \ (1)
  --scopes /subscriptions/<subscription_id> (2)
    1 Specify the service principal name.
    2 Specify the subscription ID.
    Example output
    Creating 'Contributor' role assignment under scope '/subscriptions/<subscription_id>'
The output includes credentials that you must protect. Be sure that you do not
include these credentials in your code or check the credentials into your source
control. For more information, see https://aka.ms/azadsp-cli
{
  "appId": "ac461d78-bf4b-4387-ad16-7e32e328aec6",
  "displayName": <service_principal>",
  "password": "00000000-0000-0000-0000-000000000000",
  "tenantId": "8049c7e9-c3de-762d-a54e-dc3f6be6a7ee"
}

  5. Record the values of the appId and password parameters from the previous output. You need these values during OpenShift Container Platform installation.

  6. Assign the User Access Administrator role by running the following command:

    $ az role assignment create --role "User Access Administrator" \
  --assignee-object-id $(az ad sp show --id <appId> --query id -o tsv) (1)
    1 Specify the appId parameter value for your service principal.
Additional resources

Supported Azure regions

The installation program dynamically generates the list of available Microsoft Azure regions based on your subscription.

Supported Azure public regions

  • australiacentral (Australia Central)

  • australiaeast (Australia East)

  • australiasoutheast (Australia South East)

  • brazilsouth (Brazil South)

  • canadacentral (Canada Central)

  • canadaeast (Canada East)

  • centralindia (Central India)

  • centralus (Central US)

  • eastasia (East Asia)

  • eastus (East US)

  • eastus2 (East US 2)

  • francecentral (France Central)

  • germanywestcentral (Germany West Central)

  • japaneast (Japan East)

  • japanwest (Japan West)

  • koreacentral (Korea Central)

  • koreasouth (Korea South)

  • northcentralus (North Central US)

  • northeurope (North Europe)

  • norwayeast (Norway East)

  • southafricanorth (South Africa North)

  • southcentralus (South Central US)

  • southeastasia (Southeast Asia)

  • southindia (South India)

  • swedencentral (Sweden Central)

  • switzerlandnorth (Switzerland North)

  • uaenorth (UAE North)

  • uksouth (UK South)

  • ukwest (UK West)

  • westcentralus (West Central US)

  • westeurope (West Europe)

  • westindia (West India)

  • westus (West US)

  • westus2 (West US 2)

  • westus3 (West US 3)

Supported Azure Government regions

Support for the following Microsoft Azure Government (MAG) regions was added in OpenShift Container Platform version 4.6:

  • usgovtexas (US Gov Texas)

  • usgovvirginia (US Gov Virginia)

You can reference all available MAG regions in the Azure documentation. Other provided MAG regions are expected to work with OpenShift Container Platform, but have not been tested.

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.

You are required to use Azure virtual machines with premiumIO set to true. The machines must also have the hyperVGeneration property contain V1.

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 Azure

The following Microsoft Azure instance types have been tested with OpenShift Container Platform.

Machine types

  • standardBSFamily

  • standardDADSv5Family

  • standardDASv4Family

  • standardDASv5Family

  • standardDCSv3Family

  • standardDCSFamily

  • standardDCSv2Family

  • standardDDCSv3Family

  • standardDDSv4Family

  • standardDDSv5Family

  • standardDSFamily

  • standardDSv2Family

  • standardDSv2PromoFamily

  • standardDSv3Family

  • standardDSv4Family

  • standardDSv5Family

  • standardEADSv5Family

  • standardEASv4Family

  • standardEASv5Family

  • standardEBDSv5Family

  • standardEBSv5Family

  • standardEDSv4Family

  • standardEDSv5Family

  • standardEIADSv5Family

  • standardEIASv4Family

  • standardEIASv5Family

  • standardEIDSv5Family

  • standardEISv3Family

  • standardEISv5Family

  • standardESv3Family

  • standardESv4Family

  • standardESv5Family

  • standardFXMDVSFamily

  • standardFSFamily

  • standardFSv2Family

  • standardGSFamily

  • standardHBrsv2Family

  • standardHBSFamily

  • standardHCSFamily

  • standardLASv3Family

  • standardLSFamily

  • standardLSv2Family

  • standardLSv3Family

  • standardMDSMediumMemoryv2Family

  • standardMIDSMediumMemoryv2Family

  • standardMISMediumMemoryv2Family

  • standardMSFamily

  • standardMSMediumMemoryv2Family

  • StandardNCADSA100v4Family

  • Standard NCASv3_T4 Family

  • standardNCSv2Family

  • standardNCSv3Family

  • standardNDSv2Family

  • standardNPSFamily

  • StandardNVADSA10v5Family

  • standardNVSv3Family

  • standardXEISv4Family

Selecting an Azure Marketplace image

If you are deploying an OpenShift Container Platform cluster using the Azure Marketplace offering, you must first obtain the Azure Marketplace image. The installation program uses this image to deploy worker nodes. When obtaining your image, consider the following:

  • While the images are the same, the Azure Marketplace publisher is different depending on your region. If you are located in North America, specify redhat as the publisher. If you are located in EMEA, specify redhat-limited as the publisher.

  • The offer includes a rh-ocp-worker SKU and a rh-ocp-worker-gen1 SKU. The rh-ocp-worker SKU represents a Hyper-V generation version 2 VM image. The default instance types used in OpenShift Container Platform are version 2 compatible. If you are going to use an instance type that is only version 1 compatible, use the image associated with the rh-ocp-worker-gen1 SKU. The rh-ocp-worker-gen1 SKU represents a Hyper-V version 1 VM image.

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