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Installing a cluster quickly on oVirt

You can quickly install a default, non-customized, OKD cluster on a oVirt cluster, similar to the one shown in the following diagram.

Diagram of an OKD cluster on a oVirt cluster

The installation program uses installer-provisioned infrastructure to automate creating and deploying the cluster.

To install a default cluster, you prepare the environment, run the installation program and answer its prompts. Then, the installation program creates the OKD cluster.

For an alternative to installing a default cluster, see Installing a cluster with customizations.

This installation program is available for Linux and macOS only.

Prerequisites

Requirements for the oVirt environment

To install and run an OKD version 4 cluster, the oVirt 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 OKD 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 oVirt environment uses for non-OKD 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 OKD 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 oVirt environment, you must increase the resources accordingly.

Requirements

  • The oVirt version is 4.4.

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

  • The oVirt data center contains an oVirt cluster.

  • The oVirt cluster has the following resources exclusively for the OKD 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 oVirt storage domain must meet these etcd backend performance requirements.

  • For affinity group support: Three or more hosts in the oVirt cluster. If necessary, you can disable affinity groups. For details, see Example: Removing all affinity groups for a non-production lab setup in Installing a cluster on oVirt with customizations

  • 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 OKD 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 OKD cluster.

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

  • The oVirt cluster must have a virtual network with access to the REST API on the oVirt Engine. 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 OKD cluster on the target oVirt 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 oVirt during the installation process. The installation program saves the credentials you provide to a temporary ovirt-config.yaml file that might be compromised.
Additional resources

Verifying the requirements for the oVirt environment

Verify that the oVirt environment meets the requirements to install and run an OKD 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 OKD machines, adjust these requirements accordingly.
Procedure

  1. Check that the oVirt version supports installation of OKD version 4.

    1. In the oVirt 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 oVirt Software Version.

    3. Confirm that the oVirt version is 4.4. For more information about supported version combinations, see Support Matrix for OKD on oVirt.

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

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

    2. Confirm that the data center where you plan to install OKD 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 OKD 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 oVirt cluster where you plan to install OKD. Record the cluster name for use later on.

  3. Inspect the oVirt host resources.

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

    2. Click the cluster where you plan to install OKD.

    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 OKD 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 OKD 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 OKD has access to the oVirt Engine’s REST API. From a virtual machine on this network, use curl to reach the oVirt Engine’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 oVirt account with privileges to create and manage an OKD cluster on oVirt. For <profile>, specify the login profile, which you can get by going to the oVirt 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 oVirt environment.

    For example:

    $ curl -k -u admin@internal:pw123 \
https://ovirtlab.example.com/ovirt-engine/api

Preparing the network environment on oVirt

Configure two static IP addresses for the OKD cluster and create DNS entries using these addresses.

Procedure

  1. Reserve two static IP addresses

    1. On the network where you plan to install OKD, identify two static IP addresses that are outside the DHCP lease pool.

    2. Connect to a host on this network and verify that each of the IP addresses is not in use. For example, use Address Resolution Protocol (ARP) to check that none of the IP addresses have entries:

      $ arp 10.35.1.19
      Example output
      10.35.1.19 (10.35.1.19) -- no entry

    3. Reserve two static IP addresses following the standard practices for your network environment.

    4. Record these IP addresses for future reference.

  2. Create DNS entries for the OKD REST API and apps domain names using this format:

    api.<cluster-name>.<base-domain>   <ip-address> (1)
*.apps.<cluster-name>.<base-domain>   <ip-address> (2)
    1 For <cluster-name>, <base-domain>, and <ip-address>, specify the cluster name, base domain, and static IP address of your OKD API.
    2 Specify the cluster name, base domain, and static IP address of your OKD apps for Ingress and the load balancer.

    For example:

    api.my-cluster.virtlab.example.com	10.35.1.19
*.apps.my-cluster.virtlab.example.com	10.35.1.20

Installing OKD on oVirt in insecure mode

By default, the installer creates a CA certificate, prompts you for confirmation, and stores the certificate to use during installation. You do not need to create or install one manually.

Although it is not recommended, you can override this functionality and install OKD without verifying a certificate by installing OKD on oVirt in insecure mode.

Installing in insecure mode is not recommended, because it enables a potential attacker to perform a Man-in-the-Middle attack and capture sensitive credentials on the network.
Procedure

  1. Create a file named ~/.ovirt/ovirt-config.yaml.

  2. Add the following content to ovirt-config.yaml:

    ovirt_url: https://ovirt.example.com/ovirt-engine/api (1)
ovirt_fqdn: ovirt.example.com (2)
ovirt_pem_url: ""
ovirt_username: admin@internal
ovirt_password: super-secret-password (3)
ovirt_insecure: true
    1 Specify the hostname or address of your oVirt engine.
    2 Specify the fully qualified domain name of your oVirt engine.
    3 Specify the admin password for your oVirt engine.

  3. Run the installer.

Generating a key pair for cluster node SSH access

During an OKD installation, you can provide an SSH public key to the installation program. The key is passed to the Fedora CoreOS (FCOS) nodes through their Ignition config files and is used to authenticate SSH access to the nodes. The key is added to the ~/.ssh/authorized_keys list for the core user on each node, which enables password-less authentication.

After the key is passed to the nodes, you can use the key pair to SSH in to the FCOS nodes as the user core. To access the nodes through SSH, the private key identity must be managed by SSH for your local user.

If you want to SSH in to your cluster nodes to perform installation debugging or disaster recovery, you must provide the SSH public key during the installation process. The ./openshift-install gather command also requires the SSH public key to be in place on the cluster nodes.

Do not skip this procedure in production environments, where disaster recovery and debugging is required.

On clusters running Fedora CoreOS (FCOS), the SSH keys specified in the Ignition config files are written to the /home/core/.ssh/authorized_keys.d/core file. However, the Machine Config Operator manages SSH keys in the /home/core/.ssh/authorized_keys file and configures sshd to ignore the /home/core/.ssh/authorized_keys.d/core file. As a result, newly provisioned OKD nodes are not accessible using SSH until the Machine Config Operator reconciles the machine configs with the authorized_keys file. After you can access the nodes using SSH, you can delete the /home/core/.ssh/authorized_keys.d/core file.
Procedure

  1. If you do not have an existing SSH key pair on your local machine to use for authentication onto your cluster nodes, create one. For example, on a computer that uses a Linux operating system, run the following command:

    $ ssh-keygen -t ed25519 -N '' -f <path>/<file_name> (1)
    1 Specify the path and file name, such as ~/.ssh/id_ed25519, of the new SSH key. If you have an existing key pair, ensure your public key is in the your ~/.ssh directory.

    If you plan to install an OKD cluster that uses FIPS Validated / Modules in Process cryptographic libraries on the x86_64 architecture, do not create a key that uses the ed25519 algorithm. Instead, create a key that uses the rsa or ecdsa algorithm.

  2. View the public SSH key:

    $ cat <path>/<file_name>.pub

    For example, run the following to view the ~/.ssh/id_ed25519.pub public key:

    $ cat ~/.ssh/id_ed25519.pub

  3. Add the SSH private key identity to the SSH agent for your local user, if it has not already been added. SSH agent management of the key is required for password-less SSH authentication onto your cluster nodes, or if you want to use the ./openshift-install gather command.

    On some distributions, default SSH private key identities such as ~/.ssh/id_rsa and ~/.ssh/id_dsa are managed automatically.

    1. If the ssh-agent process is not already running for your local user, start it as a background task:

      $ eval "$(ssh-agent -s)"
      Example output
      Agent pid 31874

      If your cluster is in FIPS mode, only use FIPS-compliant algorithms to generate the SSH key. The key must be either RSA or ECDSA.

  4. Add your SSH private key to the ssh-agent:

    $ ssh-add <path>/<file_name> (1)
    1 Specify the path and file name for your SSH private key, such as ~/.ssh/id_ed25519
    Example output