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Prerequisites - Deploying installer-provisioned clusters on bare metal | Installing | OpenShift Container Platform 4.7
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Prerequisites

Installer-provisioned installation of OpenShift Container Platform requires:

  1. One provisioner node with Red Hat Enterprise Linux (RHEL) 8.x installed.

  2. Three control plane nodes.

  3. Baseboard Management Controller (BMC) access to each node.

  4. At least one network:

    1. One required routable network

    2. One optional network for provisioning nodes; and,

    3. One optional management network.

Before starting an installer-provisioned installation of OpenShift Container Platform, ensure the hardware environment meets the following requirements.

Node requirements

Installer-provisioned installation involves a number of hardware node requirements:

  • CPU architecture: All nodes must use x86_64 CPU architecture.

  • Similar nodes: Red Hat recommends nodes have an identical configuration per role. That is, Red Hat recommends nodes be the same brand and model with the same CPU, memory, and storage configuration.

  • Baseboard Management Controller: The provisioner node must be able to access the baseboard management controller (BMC) of each OpenShift Container Platform cluster node. You may use IPMI, Redfish, or a proprietary protocol.

  • Latest generation: Nodes must be of the most recent generation. Because the installer-provisioned installation relies on BMC protocols, the hardware must support IPMI cipher suite 17. Additionally, RHEL 8 ships with the most recent drivers for RAID controllers. Ensure that the nodes are recent enough to support RHEL 8 for the provisioner node and RHCOS 8 for the control plane and worker nodes.

  • Registry node: (Optional) If setting up a disconnected mirrored registry, it is recommended the registry reside in its own node.

  • Provisioner node: Installer-provisioned installation requires one provisioner node.

  • Control plane: Installer-provisioned installation requires three control plane nodes for high availability.

  • Worker nodes: While not required, a typical production cluster has one or more worker nodes. Smaller clusters are more resource efficient for administrators and developers during development, production, and testing.

  • Network interfaces: Each node must have at least one network interface for the routable baremetal network. Each node must have one network interface for a provisioning network when using the provisioning network for deployment. Using the provisioning network is the default configuration. Network interface naming must be consistent across control plane nodes for the provisioning network. For example, if a control plane node uses the eth0 NIC for the provisioning network, the other control plane nodes must use it as well.

  • Unified Extensible Firmware Interface (UEFI): Installer-provisioned installation requires UEFI boot on all OpenShift Container Platform nodes when using IPv6 addressing on the provisioning network. In addition, UEFI Device PXE Settings must be set to use the IPv6 protocol on the provisioning network NIC, but omitting the provisioning network removes this requirement.

    When starting the installation from virtual media such as an ISO image, delete all old UEFI boot table entries. If the boot table includes entries that are not generic entries provided by the firmware, the installation might fail.

  • Secure Boot: Many production scenarios require nodes with Secure Boot enabled to verify the node only boots with trusted software, such as UEFI firmware drivers, EFI applications, and the operating system. To deploy an OpenShift Container Platform cluster with Secure Boot, you must enable UEFI boot mode and Secure Boot on each control plane node and each worker node. Red Hat supports Secure Boot only when installer-provisioned installations use Red Fish Virtual Media. Red Hat does not support Secure Boot with self-generated keys.

Firmware requirements for installing with virtual media

The installer for installer-provisioned OpenShift Container Platform clusters validates the hardware and firmware compatibility with Redfish virtual media. The following table lists supported firmware for installer-provisioned OpenShift Container Platform clusters deployed with Redfish virtual media.

Table 1. Firmware compatibility for Redfish virtual media
Hardware Model Management Firmware Versions

HP

10th Generation

iLO5

N/A

Dell

14th Generation

iDRAC 9

v4.20.20.20 - 04.40.00.00

13th Generation

iDRAC 8

v2.75.75.75+

Refer to the hardware documentation for the nodes or contact the hardware vendor for information on updating the firmware.

For HP servers, Redfish virtual media is not supported on 9th generation systems running iLO4, because Ironic does not support iLO4 with virtual media.

For Dell servers, ensure the OpenShift Container Platform cluster nodes have AutoAttach Enabled through the iDRAC console. The menu path is: Configuration → Virtual Media → Attach Mode → AutoAttach . With iDRAC 9 firmware version 04.40.00.00, the Virtual Console plug-in defaults to eHTML5, which causes problems with the InsertVirtualMedia workflow. Set the plug-in to HTML5 to avoid this issue. The menu path is: Configuration → Virtual console → Plug-in Type → HTML5 .

The installer will not initiate installation on a node if the node firmware is below the foregoing versions when installing with virtual media.

Network requirements

Installer-provisioned installation of OpenShift Container Platform involves several network requirements. First, installer-provisioned installation involves an optional non-routable provisioning network for provisioning the operating system on each bare metal node. Second, installer-provisioned installation involves a routable baremetal network.

Configuring NICs

OpenShift Container Platform deploys with two networks:

  • provisioning: The provisioning network is an optional non-routable network used for provisioning the underlying operating system on each node that is a part of the OpenShift Container Platform cluster. When deploying using the provisioning network, the first NIC on each node, such as eth0 or eno1, must interface with the provisioning network.

  • baremetal: The baremetal network is a routable network. When deploying using the provisioning network, the second NIC on each node, such as eth1 or eno2, must interface with the baremetal network. When deploying without a provisioning network, you can use any NIC on each node to interface with the baremetal network.

Each NIC should be on a separate VLAN corresponding to the appropriate network.

Configuring the DNS server

Clients access the OpenShift Container Platform cluster nodes over the baremetal network. A network administrator must configure a subdomain or subzone where the canonical name extension is the cluster name.

<cluster_name>.<domain-name>

For example:

test-cluster.example.com

OpenShift Container Platform includes functionality that uses cluster membership information to generate A/AAAA records. This resolves the node names to their IP addresses. Once the nodes are registered with the API, the cluster can disperse node information without using CoreDNS-mDNS. This eliminates the network traffic associated with multicast DNS.

Dynamic Host Configuration Protocol (DHCP) requirements

By default, installer-provisioned installation deploys ironic-dnsmasq with DHCP enabled for the provisioning network. No other DHCP servers should be running on the provisioning network when the provisioningNetwork configuration setting is set to managed, which is the default value. If you have a DHCP server running on the provisioning network, you must set the provisioningNetwork configuration setting to unmanaged in the install-config.yaml file.

Network administrators must reserve IP addresses for each node in the OpenShift Container Platform cluster for the baremetal network on an external DHCP server.

Reserving IP addresses for nodes with the DHCP server

For the baremetal network, a network administrator must reserve a number of IP addresses to ensure that they do not change after deployment, including:

  1. Two virtual IP addresses:

    • One IP address for the API endpoint.

    • One IP address for the wildcard ingress endpoint.

  2. One IP address for the provisioner node.

  3. One IP address for each control plane (master) node.

  4. One IP address for each worker node.

Reserving IP addresses so they become static IP addresses

Some administrators prefer to use static IP addresses so that each node’s IP address remains constant in the absence of a DHCP server. To use static IP addresses in the OpenShift Container Platform cluster, reserve the IP addresses with an infinite lease. During deployment, the installer will reconfigure the NICs from DHCP assigned addresses to static IP addresses. NICs with DHCP leases that are not infinite will remain configured to use DHCP.

Setting IP addresses with an infinite lease is incompatible with network configuration deployed by using the Machine Config Operator.
Ensuring that your DHCP server can provide infinite leases

Your DHCP server must provide a DHCP expiration time of 4294967295 seconds to properly set an infinite lease as specified by rfc2131. If a lesser value is returned for the DHCP infinite lease time, the node reports an error and a permanent IP is not set for the node. In RHEL 8, dhcpd does not provide infinite leases. If you want to use the provisioner node to serve dynamic IP addresses with infinite lease times, use dnsmasq rather than dhcpd.
Do not change IP addresses manually after deployment

Do not change a worker node’s IP address manually after deployment. To change the IP address of a worker node after deployment, you must mark the worker node unschedulable, evacuate the pods, delete the node, and recreate it with the new IP address. See "Working with nodes" for additional details. To change the IP address of a control plane node after deployment, contact support.

The storage interface requires a DHCP reservation.

The following table provides an exemplary embodiment of fully qualified domain names. The API and Nameserver addresses begin with canonical name extensions. The hostnames of the control plane and worker nodes are exemplary, so you can use any host naming convention you prefer.

Usage Host Name IP

API

api.<cluster_name>.<domain>

<ip>

Ingress LB (apps)

*.apps.<cluster_name>.<domain>

<ip>

Provisioner node

provisioner.<cluster_name>.<domain>

<ip>

master-0

openshift-master-0.<cluster_name>.<domain>

<ip>

master-1

openshift-master-1.<cluster_name>.<domain>

<ip>

master-2

openshift-master-2.<cluster_name>.<domain>

<ip>

Worker-0

openshift-worker-0.<cluster_name>.<domain>

<ip>

Worker-1

openshift-worker-1.<cluster_name>.<domain>

<ip>

Worker-n

openshift-worker-n.<cluster_name>.<domain>

<ip>

Network Time Protocol (NTP)

Each OpenShift Container Platform node in the cluster must have access to an NTP server. OpenShift Container Platform nodes use NTP to synchronize their clocks. For example, cluster nodes use SSL certificates that require validation, which might fail if the date and time between the nodes are not in sync.

Define a consistent clock date and time format in each cluster node’s BIOS settings, or installation might fail.

You may reconfigure the control plane nodes to act as NTP servers on disconnected clusters, and reconfigure worker nodes to retrieve time from the control plane nodes.

State-driven network configuration requirements (Technology Preview)

OpenShift Container Platform supports additional post-installation state-driven network configuration on the secondary network interfaces of cluster nodes using kubernetes-nmstate. For example, system administrators might configure a secondary network interface on cluster nodes after installation for a storage network.

Configuration must occur before scheduling pods.

State-driven network configuration requires installing kubernetes-nmstate, and also requires Network Manager running on the cluster nodes. See OpenShift Virtualization > Kubernetes NMState (Tech Preview) for additional details.

Port access for the out-of-band management IP address

The out-of-band management IP address is on a separate network from the node. To ensure that the out-of-band management can communicate with the baremetal node during installation, the out-of-band management IP address address must be granted access to the TCP 6180 port.

Configuring nodes

Configuring nodes when using the provisioning network

Each node in the cluster requires the following configuration for proper installation.

A mismatch between nodes will cause an installation failure.

While the cluster nodes can contain more than two NICs, the installation process only focuses on the first two NICs:

NIC

Network

VLAN

NIC1

provisioning

<provisioning-vlan>

NIC2

baremetal

<baremetal-vlan>

NIC1 is a non-routable network (provisioning) that is only used for the installation of the OpenShift Container Platform cluster.

The Red Hat Enterprise Linux (RHEL) 8.x installation process on the provisioner node might vary. To install Red Hat Enterprise Linux (RHEL) 8.x using a local Satellite server or a PXE server, PXE-enable NIC2.

PXE

Boot order

NIC1 PXE-enabled provisioning network

1

NIC2 baremetal network. PXE-enabled is optional.

2

Ensure PXE is disabled on all other NICs.

Configure the control plane and worker nodes as follows:

PXE

Boot order

NIC1 PXE-enabled (provisioning network)

1
Configuring nodes without the provisioning network

The installation process requires one NIC:

NIC

Network

VLAN

NICx

baremetal

<baremetal-vlan>

NICx is a routable network (baremetal) that is used for the installation of the OpenShift Container Platform cluster, and routable to the internet.

Configuring nodes for Secure Boot

Secure Boot prevents a node from booting unless it verifies the node is using only trusted software, such as UEFI firmware drivers, EFI applications and the operating system. Red Hat only supports Secure Boot when deploying with RedFish Virtual Media.

To enable Secure Boot, refer to the hardware guide for the node. To enable Secure Boot, execute the following:

  1. Boot the node and enter the BIOS menu.

  2. Set the node’s boot mode to UEFI Enabled.

  3. Enable Secure Boot.

    Red Hat does not support Secure Boot with self-generated keys.

Out-of-band management

Nodes will typically have an additional NIC used by the Baseboard Management Controllers (BMCs). These BMCs must be accessible from the provisioner node.

Each node must be accessible via out-of-band management. When using an out-of-band management network, the provisioner node requires access to the out-of-band management network for a successful OpenShift Container Platform 4 installation.

The out-of-band management setup is out of scope for this document. We recommend setting up a separate management network for out-of-band management. However, using the provisioning network or the baremetal network are valid options.

Required data for installation

Prior to the installation of the OpenShift Container Platform cluster, gather the following information from all cluster nodes:

  • Out-of-band management IP

    • Examples

      • Dell (iDRAC) IP

      • HP (iLO) IP

      • Fujitsu (iRMC) IP

When using the provisioning network

  • NIC1 (provisioning) MAC address

  • NIC2 (baremetal) MAC address

When omitting the provisioning network

  • NICx (baremetal) MAC address

Validation checklist for nodes

When using the provisioning network

  • NIC1 VLAN is configured for the provisioning network. (optional)

  • NIC1 is PXE-enabled on the provisioner, control plane (master), and worker nodes when using a provisioning network. (optional)

  • NIC2 VLAN is configured for the baremetal network.

  • PXE has been disabled on all other NICs.

  • Control plane and worker nodes are configured.

  • All nodes accessible via out-of-band management.

  • A separate management network has been created. (optional)

  • Required data for installation.

When omitting the provisioning network

  • NICx VLAN is configured for the baremetal network.

  • Control plane and worker nodes are configured.

  • All nodes accessible via out-of-band management.

  • A separate management network has been created. (optional)

  • Required data for installation.