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Prerequisites - Deploying installer-provisioned clusters on IBM Cloud | Installing | OpenShift Container Platform 4.9
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Prerequisites

You can use installer-provisioned installation to install OpenShift Container Platform on IBM Cloud® nodes. This document describes the prerequisites and procedures when installing OpenShift Container Platform on IBM Cloud nodes.

Red Hat supports IPMI and PXE on the provisioning network only. Red Hat has not tested Red Fish, virtual media, or other complementary technologies such as Secure Boot on IBM Cloud deployments. The provisioning network is required.

Installer-provisioned installation of OpenShift Container Platform requires:

  • One provisioner node with Red Hat Enterprise Linux CoreOS (RHCOS) 8.x installed

  • Three control plane nodes

  • One routable network

  • One network for provisioning nodes

Before starting an installer-provisioned installation of OpenShift Container Platform on IBM Cloud, address the following prerequisites and requirements.

Setting up IBM Cloud infrastructure

To deploy an OpenShift Container Platform cluster on IBM Cloud®, you must first provision the IBM Cloud nodes.

Red Hat supports IPMI and PXE on the provisioning network only. Red Hat has not tested Red Fish, virtual media, or other complementary technologies such as Secure Boot on IBM Cloud deployments. The provisioning network is required.

You can customize IBM Cloud nodes using the IBM Cloud API. When creating IBM Cloud nodes, you must consider the following requirements.

Use one data center per cluster

All nodes in the OpenShift Container Platform cluster must run in the same IBM Cloud data center.

Create public and private VLANs

Create all nodes with a single public VLAN and a single private VLAN.

Ensure subnets have sufficient IP addresses

IBM Cloud public VLAN subnets use a /28 prefix by default, which provides 16 IP addresses. That is sufficient for a cluster consisting of three control plane nodes, four worker nodes, and two IP addresses for the API VIP and Ingress VIP on the baremetal network. For larger clusters, you might need a smaller prefix.

IBM Cloud private VLAN subnets use a /26 prefix by default, which provides 64 IP addresses. IBM Cloud will use private network IP addresses to access the Baseboard Management Controller (BMC) of each node. OpenShift Container Platform creates an additional subnet for the provisioning network. Network traffic for the provisioning network subnet routes through the private VLAN. For larger clusters, you might need a smaller prefix.

Table 1. IP addresses per prefix
IP addresses Prefix

32

/27

64

/26

128

/25

256

/24

Configuring NICs

OpenShift Container Platform deploys with two networks:

  • provisioning: The provisioning network is a non-routable network used for provisioning the underlying operating system on each node that is a part of the OpenShift Container Platform cluster.

  • baremetal: The baremetal network is a routable network. You can use any NIC order to interface with the baremetal network, provided it is not the NIC specified in the provisioningNetworkInterface configuration setting or the NIC associated to a node’s bootMACAddress configuration setting for the provisioning network.

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

NIC Network VLAN

NIC1

provisioning

<provisioning_vlan>

NIC2

baremetal

<baremetal_vlan>

In the previous example, NIC1 on all control plane and worker nodes connects to the non-routable network (provisioning) that is only used for the installation of the OpenShift Container Platform cluster. NIC2 on all control plane and worker nodes connects to the routable baremetal network.

PXE Boot order

NIC1 PXE-enabled provisioning network

1

NIC2 baremetal network.

2

Ensure PXE is enabled on the NIC used for the provisioning network and is disabled on all other NICs.

Configuring canonical names

Clients access the OpenShift Container Platform cluster nodes over the baremetal network. Configure IBM Cloud subdomains or subzones where the canonical name extension is the cluster name.

<cluster_name>.<domain>

For example:

test-cluster.example.com

Creating DNS entries

You must create DNS A record entries resolving to unused IP addresses on the public subnet for the following:

Usage Host Name IP

API

api.<cluster_name>.<domain>

<ip>

Ingress LB (apps)

*.apps.<cluster_name>.<domain>

<ip>

Control plane and worker nodes already have DNS entries after provisioning.

The following table provides an example of fully qualified domain names. The API and Nameserver addresses begin with canonical name extensions. The host names of the control plane and worker nodes are examples, 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>

OpenShift Container Platform includes functionality that uses cluster membership information to generate A records. This resolves the node names to their IP addresses. After 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.

After provisioning the IBM Cloud nodes, you must create a DNS entry for the api.<cluster_name>.<domain> domain name on the external DNS because removing CoreDNS causes the local entry to disappear. Failure to create a DNS record for the api.<cluster_name>.<domain> domain name in the external DNS server prevents worker nodes from joining the cluster.

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.

Configure a DHCP server

IBM Cloud does not run DHCP on the public or private VLANs. After provisioning IBM Cloud nodes, you must set up a DHCP server for the public VLAN, which corresponds to OpenShift Container Platform’s baremetal network.

The IP addresses allocated to each node do not need to match the IP addresses allocated by the IBM Cloud provisioning system.

See the "Configuring the public subnet" section for details.

Ensure BMC access privileges

The "Remote management" page for each node on the dashboard contains the node’s intelligent platform management interface (IPMI) credentials. The default IPMI privileges prevent the user from making certain boot target changes. You must change the privilege level to OPERATOR so that Ironic can make those changes.

In the install-config.yaml file, add the privilegelevel parameter to the URLs used to configure each BMC. See the "Configuring the install-config.yaml file" section for additional details. For example:

ipmi://<IP>:<port>?privilegelevel=OPERATOR

Alternatively, contact IBM Cloud support and request that they increase the IPMI privileges to ADMINISTRATOR for each node.

Create bare metal servers

Create bare metal servers in the IBM Cloud dashboard by navigating to Create resource → Bare Metal Server.

Alternatively, you can create bare metal servers with the ibmcloud CLI utility. For example:

$ ibmcloud sl hardware create --hostname <SERVERNAME> \
                            --domain <DOMAIN> \
                            --size <SIZE> \
                            --os <OS-TYPE> \
                            --datacenter <DC-NAME> \
                            --port-speed <SPEED> \
                            --billing <BILLING>

See Installing the stand-alone IBM Cloud CLI for details on installing the IBM Cloud CLI.

IBM Cloud servers might take 3-5 hours to become available.