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Installing a cluster on RHV with user-provisioned infrastructure

In OpenShift Container Platform version 4.9, you can install a customized OpenShift Container Platform cluster on Red Hat Virtualization (RHV) and other infrastructure that you provide. The OpenShift Container Platform documentation uses the term user-provisioned infrastructure to refer to this infrastructure type.

The following diagram shows an example of a potential OpenShift Container Platform cluster running on a RHV cluster.

Diagram of an OpenShift Container Platform cluster on a RHV cluster

The RHV hosts run virtual machines that contain both control plane and compute pods. One of the hosts also runs a Manager virtual machine and a bootstrap virtual machine that contains a temporary control plane pod.]

Prerequisites

The following items are required to install an OpenShift Container Platform cluster on a RHV environment.

Internet access for OpenShift Container Platform

In OpenShift Container Platform 4.9, you require access to the internet to install your cluster.

You must have internet access to:

  • Access the Red Hat OpenShift Cluster Manager page 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 the RHV environment

To install and run an OpenShift Container Platform version 4.9 cluster, the RHV environment must meet the following requirements.

Not meeting these requirements can cause the installation or process to fail. Additionally, not meeting these requirements can cause the OpenShift Container Platform cluster to fail days or weeks after installation.

The following requirements for CPU, memory, and storage resources are based on default values multiplied by the default number of virtual machines the installation program creates. These resources must be available in addition to what the RHV environment uses for non-OpenShift Container Platform operations.

By default, the installation program creates seven virtual machines during the installation process. First, it creates a bootstrap virtual machine to provide temporary services and a control plane while it creates the rest of the OpenShift Container Platform cluster. When the installation program finishes creating the cluster, deleting the bootstrap machine frees up its resources.

If you increase the number of virtual machines in the RHV environment, you must increase the resources accordingly.

Requirements

  • The RHV version is 4.4.

  • The RHV environment has one data center whose state is Up.

  • The RHV data center contains an RHV cluster.

  • The RHV cluster has the following resources exclusively for the OpenShift Container Platform cluster:

    • Minimum 28 vCPUs: four for each of the seven virtual machines created during installation.

    • 112 GiB RAM or more, including:

      • 16 GiB or more for the bootstrap machine, which provides the temporary control plane.

      • 16 GiB or more for each of the three control plane machines which provide the control plane.

      • 16 GiB or more for each of the three compute machines, which run the application workloads.

  • The RHV storage domain must meet these etcd backend performance requirements.

  • In production environments, each virtual machine must have 120 GiB or more. Therefore, the storage domain must provide 840 GiB or more for the default OpenShift Container Platform cluster. In resource-constrained or non-production environments, each virtual machine must have 32 GiB or more, so the storage domain must have 230 GiB or more for the default OpenShift Container Platform cluster.

  • To download images from the Red Hat Ecosystem Catalog during installation and update procedures, the RHV cluster must have access to an internet connection. The Telemetry service also needs an internet connection to simplify the subscription and entitlement process.

  • The RHV cluster must have a virtual network with access to the REST API on the RHV Manager. Ensure that DHCP is enabled on this network, because the VMs that the installer creates obtain their IP address by using DHCP.

  • A user account and group with the following least privileges for installing and managing an OpenShift Container Platform cluster on the target RHV cluster:

    • DiskOperator

    • DiskCreator

    • UserTemplateBasedVm

    • TemplateOwner

    • TemplateCreator

    • ClusterAdmin on the target cluster

Apply the principle of least privilege: Avoid using an administrator account with SuperUser privileges on RHV during the installation process. The installation program saves the credentials you provide to a temporary ovirt-config.yaml file that might be compromised.

Verifying the requirements for the RHV environment

Verify that the RHV environment meets the requirements to install and run an OpenShift Container Platform cluster. Not meeting these requirements can cause failures.

These requirements are based on the default resources the installation program uses to create control plane and compute machines. These resources include vCPUs, memory, and storage. If you change these resources or increase the number of OpenShift Container Platform machines, adjust these requirements accordingly.
Procedure

  1. Check that the RHV version supports installation of OpenShift Container Platform version 4.9.

    1. In the RHV Administration Portal, click the ? help icon in the upper-right corner and select About.

    2. In the window that opens, make a note of the RHV Software Version.

    3. Confirm that the RHV version is 4.4. For more information about supported version combinations, see Support Matrix for OpenShift Container Platform on RHV.

  2. Inspect the data center, cluster, and storage.

    1. In the RHV Administration Portal, click Compute → Data Centers.

    2. Confirm that the data center where you plan to install OpenShift Container Platform is accessible.

    3. Click the name of that data center.

    4. In the data center details, on the Storage tab, confirm the storage domain where you plan to install OpenShift Container Platform is Active.

    5. Record the Domain Name for use later on.

    6. Confirm Free Space has at least 230 GiB.

    7. Confirm that the storage domain meets these etcd backend performance requirements, which you can measure by using the fio performance benchmarking tool.

    8. In the data center details, click the Clusters tab.

    9. Find the RHV cluster where you plan to install OpenShift Container Platform. Record the cluster name for use later on.

  3. Inspect the RHV host resources.

    1. In the RHV Administration Portal, click Compute > Clusters.

    2. Click the cluster where you plan to install OpenShift Container Platform.

    3. In the cluster details, click the Hosts tab.

    4. Inspect the hosts and confirm they have a combined total of at least 28 Logical CPU Cores available exclusively for the OpenShift Container Platform cluster.

    5. Record the number of available Logical CPU Cores for use later on.

    6. Confirm that these CPU cores are distributed so that each of the seven virtual machines created during installation can have four cores.

    7. Confirm that, all together, the hosts have 112 GiB of Max free Memory for scheduling new virtual machines distributed to meet the requirements for each of the following OpenShift Container Platform machines:

      • 16 GiB required for the bootstrap machine

      • 16 GiB required for each of the three control plane machines

      • 16 GiB for each of the three compute machines

    8. Record the amount of Max free Memory for scheduling new virtual machines for use later on.

  4. Verify that the virtual network for installing OpenShift Container Platform has access to the RHV Manager’s REST API. From a virtual machine on this network, use curl to reach the RHV Manager’s REST API:

    $ curl -k -u <username>@<profile>:<password> \ (1)
https://<engine-fqdn>/ovirt-engine/api (2)
    1 For <username>, specify the user name of an RHV account with privileges to create and manage an OpenShift Container Platform cluster on RHV. For <profile>, specify the login profile, which you can get by going to the RHV Administration Portal login page and reviewing the Profile dropdown list. For <password>, specify the password for that user name.
    2 For <engine-fqdn>, specify the fully qualified domain name of the RHV environment.

    For example:

    $ curl -k -u ocpadmin@internal:pw123 \
https://rhv-env.virtlab.example.com/ovirt-engine/api

Networking requirements for user-provisioned infrastructure

All the Red Hat Enterprise Linux CoreOS (RHCOS) machines require networking to be configured in initramfs during boot to fetch their Ignition config files.

During the initial boot, the machines require an IP address configuration that is set either through a DHCP server or statically by providing the required boot options. After a network connection is established, the machines download their Ignition config files from an HTTP or HTTPS server. The Ignition config files are then used to set the exact state of each machine. The Machine Config Operator completes more changes to the machines, such as the application of new certificates or keys, after installation.

It is recommended to use a DHCP server for long-term management of the cluster machines. Ensure that the DHCP server is configured to provide persistent IP addresses, DNS server information, and hostnames to the cluster machines.

If a DHCP service is not available for your user-provisioned infrastructure, you can instead provide the IP networking configuration and the address of the DNS server to the nodes at RHCOS install time. These can be passed as boot arguments if you are installing from an ISO image. See the Installing RHCOS and starting the OpenShift Container Platform bootstrap process section for more information about static IP provisioning and advanced networking options.

The Kubernetes API server must be able to resolve the node names of the cluster machines. If the API servers and worker nodes are in different zones, you can configure a default DNS search zone to allow the API server to resolve the node names. Another supported approach is to always refer to hosts by their fully-qualified domain names in both the node objects and all DNS requests.

Firewall

Configure your firewall so your cluster has access to required sites.

See also:

Load balancers

Configure one or preferably two layer-4 load balancers:

  • Provide load balancing for ports 6443 and 22623 on the control plane and bootstrap machines. Port 6443 provides access to the Kubernetes API server and must be reachable both internally and externally. Port 22623 must be accessible to nodes within the cluster.

  • Provide load balancing for port 443 and 80 for machines that run the Ingress router, which are usually compute nodes in the default configuration. Both ports must be accessible from within and outside the cluster.

DNS

Configure infrastructure-provided DNS to allow the correct resolution of the main components and services. If you use only one load balancer, these DNS records can point to the same IP address.

  • Create DNS records for api