vSphere installation requirements for user-provisioned infrastructure

Before you begin an installation on infrastructure that you provision, be sure that your vSphere environment meets the following installation requirements.

VMware vSphere infrastructure requirements

You must install the OKD cluster on a VMware vSphere version 7.0 Update 2 or later instance that meets the requirements for the components that you use.

You can host the VMware vSphere infrastructure on-premise or on a VMware Cloud Verified provider that meets the requirements outlined in the following tables:

VMware vSphere CSI Driver Operator requirements

To install the vSphere CSI Driver Operator, the following requirements must be met:

• VMware vSphere version 7.0 Update 2 or later

• vCenter 7.0 Update 2 or later

• Virtual machines of hardware version 15 or later

• No third-party vSphere CSI driver already installed in the cluster

If a third-party vSphere CSI driver is present in the cluster, OKD does not overwrite it. The presence of a third-party vSphere CSI driver prevents OKD from updating to OKD 4.13 or later.

Additional resources

• To remove a third-party vSphere CSI driver, see Removing a third-party vSphere CSI Driver.

• To update the hardware version for your vSphere nodes, see Updating hardware on nodes running in vSphere.

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 OKD on user-provisioned infrastructure.

vCenter requirements

Before you install an OKD cluster on your vCenter that uses infrastructure that you provided, you must prepare your environment.

Required vCenter account privileges

To install an OKD cluster in a vCenter, your vSphere account must include privileges for reading and creating the required resources. Using an account that has global administrative privileges is the simplest way to access all of the necessary permissions.

Roles and privileges required for installation in vSphere API

Roles and privileges required for installation in vCenter graphical user interface (GUI)

Additionally, the user requires some ReadOnly permissions, and some of the roles require permission to propogate the permissions to child objects. These settings vary depending on whether or not you install the cluster into an existing folder.

Required permissions and propagation settings

For more information about creating an account with only the required privileges, see vSphere Permissions and User Management Tasks in the vSphere documentation.

Using OKD with vMotion

If you intend on using vMotion in your vSphere environment, consider the following before installing an OKD cluster.

• OKD generally supports compute-only vMotion, where generally implies that you meet all VMware best practices for vMotion.

  To help ensure the uptime of your compute and control plane nodes, ensure that you follow the VMware best practices for vMotion, and use VMware anti-affinity rules to improve the availability of OKD during maintenance or hardware issues.

  For more information about vMotion and anti-affinity rules, see the VMware vSphere documentation for vMotion networking requirements and VM anti-affinity rules.

• Using Storage vMotion can cause issues and is not supported. If you are using vSphere volumes in your pods, migrating a VM across datastores, either manually or through Storage vMotion, causes invalid references within OKD persistent volume (PV) objects that can result in data loss.

• OKD does not support selective migration of VMDKs across datastores, using datastore clusters for VM provisioning or for dynamic or static provisioning of PVs, or using a datastore that is part of a datastore cluster for dynamic or static provisioning of PVs.

  You can specify the path of any datastore that exists in a datastore cluster. By default, Storage Distributed Resource Scheduler (SDRS), which uses Storage vMotion, is automatically enabled for a datastore cluster. Red Hat does not support Storage vMotion, so you must disable Storage DRS to avoid data loss issues for your OKD cluster. If you must specify VMs across multiple datastores, use a datastore object to specify a failure domain in your cluster’s install-config.yaml configuration file. For more information, see “VMware vSphere region and zone enablement”.

Cluster resources

When you deploy an OKD cluster that uses infrastructure that you provided, you must create the following resources in your vCenter instance:

• 1 Folder

• 1 Tag category

• 1 Tag

• Virtual machines:

  • 1 template

  • 1 temporary bootstrap node

  • 3 control plane nodes

  • 3 compute machines

Although these resources use 856 GB of storage, the bootstrap node is destroyed during the cluster installation process. A minimum of 800 GB of storage is required to use a standard cluster.

If you deploy more compute machines, the OKD cluster will use more storage.

Cluster limits

Available resources vary between clusters. The number of possible clusters within a vCenter is limited primarily by available storage space and any limitations on the number of required resources. Be sure to consider both limitations to the vCenter resources that the cluster creates and the resources that you require to deploy a cluster, such as IP addresses and networks.

Networking requirements

Use Dynamic Host Configuration Protocol (DHCP) for the network and ensure that the DHCP server is configured to provide persistent IP addresses to the cluster machines.

Configure the default gateway to use the DHCP server. All nodes must be in the same VLAN. You cannot scale the cluster using a second VLAN as a Day 2 operation.

You must use the Dynamic Host Configuration Protocol (DHCP) for the network and ensure that the DHCP server is configured to provide persistent IP addresses to the cluster machines. In the DHCP lease, you must configure the DHCP to use the default gateway. All nodes must be in the same VLAN. You cannot scale the cluster using a second VLAN as a Day 2 operation.

If you are installing to a restricted environment, the VM in your restricted network must have access to vCenter so that it can provision and manage nodes, persistent volume claims (PVCs), and other resources.

Additionally, you must create the following networking resources before you install the OKD cluster:

Required IP Addresses

DNS records

You must create DNS records for two static IP addresses in the appropriate DNS server for the vCenter instance that hosts your OKD cluster. In each record, <cluster_name> is the cluster name and <base_domain> is the cluster base domain that you specify when you install the cluster. A complete DNS record takes the form: <component>.<cluster_name>.<base_domain>..

Additional resources

• Creating a compute machine set on vSphere

Required machines for cluster installation

The smallest OKD clusters require the following hosts:

The bootstrap and control plane machines must use Fedora CoreOS (FCOS) as the operating system. However, the compute machines can choose between Fedora CoreOS (FCOS), Fedora 8.6 and later.

See Red Hat Enterprise Linux technology capabilities and limits.

Minimum resource requirements for cluster installation

Each cluster machine must meet the following minimum requirements:

1. OKD 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.

2. As with all user-provisioned installations, if you choose to use Fedora 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 Fedora 7 compute machines is deprecated and has been removed in OKD 4.10 and later.

If an instance type for your platform meets the minimum requirements for cluster machines, it is supported to use in OKD.

Additional resources

• Optimizing storage

Requirements for encrypting virtual machines

You can encrypt your virtual machines prior to installing OKD 4 by meeting the following requirements.

• You have configured a Standard key provider in vSphere. For more information, see Adding a KMS to vCenter Server.

  The Native key provider in vCenter is not supported. For more information, see vSphere Native Key Provider Overview.

• You have enabled host encryption mode on all of the ESXi hosts that are hosting the cluster. For more information, see Enabling host encryption mode.

• You have a vSphere account which has all cryptographic privileges enabled. For more information, see Cryptographic Operations Privileges.

When you deploy the OVF template in the section titled “Installing RHCOS and starting the OpenShift Container Platform bootstrap process”, select the option to “Encrypt this virtual machine” when you are selecting storage for the OVF template. After completing cluster installation, create a storage class that uses the encryption storage policy you used to encrypt the virtual machines.

Additional resources

• Creating an encrypted storage class

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.

Networking requirements for user-provisioned infrastructure

All the Fedora CoreOS (FCOS) 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.

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.

Setting the cluster node hostnames through DHCP

On Fedora CoreOS (FCOS) machines, the hostname is set through NetworkManager. By default, the machines obtain their hostname through DHCP. If the hostname is not provided by DHCP, set statically through kernel arguments, or another method, it is obtained through a reverse DNS lookup. Reverse DNS lookup occurs after the network has been initialized on a node and can take time to resolve. Other system services can start prior to this and detect the hostname as localhost or similar. You can avoid this by using DHCP to provide the hostname for each cluster node.

Additionally, setting the hostnames through DHCP can bypass any manual DNS record name configuration errors in environments that have a DNS split-horizon implementation.

Network connectivity requirements

You must configure the network connectivity between machines to allow OKD cluster components to communicate. Each machine must be able to resolve the hostnames of all other machines in the cluster.

This section provides details about the ports that are required.

Ethernet adaptor hardware address requirements

When provisioning VMs for the cluster, the ethernet interfaces configured for each VM must use a MAC address from the VMware Organizationally Unique Identifier (OUI) allocation ranges:

• 00:05:69:00:00:00 to 00:05:69:FF:FF:FF

• 00:0c:29:00:00:00 to 00:0c:29:FF:FF:FF

• 00:1c:14:00:00:00 to 00:1c:14:FF:FF:FF

• 00:50:56:00:00:00 to 00:50:56:3F:FF:FF

If a MAC address outside the VMware OUI is used, the cluster installation will not succeed.

NTP configuration for user-provisioned infrastructure

OKD clusters are configured to use a public Network Time Protocol (NTP) server by default. If you want to use a local enterprise NTP server, or if your cluster is being deployed in a disconnected network, you can configure the cluster to use a specific time server. For more information, see the documentation for Configuring chrony time service.

If a DHCP server provides NTP server information, the chrony time service on the Fedora CoreOS (FCOS) machines read the information and can sync the clock with the NTP servers.

Additional resources

• Configuring chrony time service

User-provisioned DNS requirements

In OKD deployments, DNS name resolution is required for the following components:

• The Kubernetes API

• The OKD application wildcard

• The bootstrap, control plane, and compute machines

Reverse DNS resolution is also required for the Kubernetes API, the bootstrap machine, the control plane machines, and the compute machines.

DNS A/AAAA or CNAME records are used for name resolution and PTR records are used for reverse name resolution. The reverse records are important because Fedora CoreOS (FCOS) uses the reverse records to set the hostnames for all the nodes, unless the hostnames are provided by DHCP. Additionally, the reverse records are used to generate the certificate signing requests (CSR) that OKD needs to operate.

The following DNS records are required for a user-provisioned OKD cluster and they must be in place before installation. In each record, <cluster_name> is the cluster name and <base_domain> is the base domain that you specify in the install-config.yaml file. A complete DNS record takes the form: <component>.<cluster_name>.<base_domain>..

Example DNS configuration for user-provisioned clusters

This section provides A and PTR record configuration samples that meet the DNS requirements for deploying OKD on user-provisioned infrastructure. The samples are not meant to provide advice for choosing one DNS solution over another.

In the examples, the cluster name is ocp4 and the base domain is example.com.

Example DNS A record configuration for a user-provisioned cluster

The following example is a BIND zone file that shows sample A records for name resolution in a user-provisioned cluster.

Sample DNS zone database

$TTL 1W
@    IN    SOA    ns1.example.com.    root (
            2019070700    ; serial
            3H        ; refresh (3 hours)
            30M        ; retry (30 minutes)
            2W        ; expiry (2 weeks)
            1W )        ; minimum (1 week)
    IN    NS    ns1.example.com.
    IN    MX 10    smtp.example.com.
;
;
ns1.example.com.        IN    A    192.168.1.5
smtp.example.com.        IN    A    192.168.1.5
;
helper.example.com.        IN    A    192.168.1.5
helper.ocp4.example.com.    IN    A    192.168.1.5
;
api.ocp4.example.com.        IN    A    192.168.1.5 (1)
api-int.ocp4.example.com.    IN    A    192.168.1.5 (2)
;
*.apps.ocp4.example.com.    IN    A    192.168.1.5 (3)
;
bootstrap.ocp4.example.com.    IN    A    192.168.1.96 (4)
;
control-plane0.ocp4.example.com.    IN    A    192.168.1.97 (5)
control-plane1.ocp4.example.com.    IN    A    192.168.1.98 (5)
control-plane2.ocp4.example.com.    IN    A    192.168.1.99 (5)
;
compute0.ocp4.example.com.    IN    A    192.168.1.11 (6)
compute1.ocp4.example.com.    IN    A    192.168.1.7 (6)
;
;EOF

Example DNS PTR record configuration for a user-provisioned cluster

The following example BIND zone file shows sample PTR records for reverse name resolution in a user-provisioned cluster.

Sample DNS zone database for reverse records

$TTL 1W
@    IN    SOA    ns1.example.com.    root (
            2019070700    ; serial
            3H        ; refresh (3 hours)
            30M        ; retry (30 minutes)
            2W        ; expiry (2 weeks)
            1W )        ; minimum (1 week)
    IN    NS    ns1.example.com.
;
5.1.168.192.in-addr.arpa.    IN    PTR    api.ocp4.example.com. (1)
5.1.168.192.in-addr.arpa.    IN    PTR    api-int.ocp4.example.com. (2)
;
96.1.168.192.in-addr.arpa.    IN    PTR    bootstrap.ocp4.example.com. (3)
;
97.1.168.192.in-addr.arpa.    IN    PTR    control-plane0.ocp4.example.com. (4)
98.1.168.192.in-addr.arpa.    IN    PTR    control-plane1.ocp4.example.com. (4)
99.1.168.192.in-addr.arpa.    IN    PTR    control-plane2.ocp4.example.com. (4)
;
11.1.168.192.in-addr.arpa.    IN    PTR    compute0.ocp4.example.com. (5)
7.1.168.192.in-addr.arpa.    IN    PTR    compute1.ocp4.example.com. (5)
;
;EOF

Load balancing requirements for user-provisioned infrastructure

Before you install OKD, you must provision the API and application Ingress load balancing infrastructure. In production scenarios, you can deploy the API and application Ingress load balancers separately so that you can scale the load balancer infrastructure for each in isolation.

The load balancing infrastructure must meet the following requirements:

1. API load balancer: Provides a common endpoint for users, both human and machine, to interact with and configure the platform. Configure the following conditions:

   • Layer 4 load balancing only. This can be referred to as Raw TCP, SSL Passthrough, or SSL Bridge mode. If you use SSL Bridge mode, you must enable Server Name Indication (SNI) for the API routes.

   • A stateless load balancing algorithm. The options vary based on the load balancer implementation.

   Do not configure session persistence for an API load balancer. Configuring session persistence for a Kubernetes API server might cause performance issues from excess application traffic for your OKD cluster and the Kubernetes API that runs inside the cluster.

   Configure the following ports on both the front and back of the load balancers:

   Table 10. API load balancer

   Port	Back-end machines (pool members)	Internal	External	Description
   6443	Bootstrap and control plane. You remove the bootstrap machine from the load balancer after the bootstrap machine initializes the cluster control plane. You must configure the /readyz endpoint for the API server health check probe.	X	X	Kubernetes API server
   22623	Bootstrap and control plane. You remove the bootstrap machine from the load balancer after the bootstrap machine initializes the cluster control plane.	X		Machine config server

   The load balancer must be configured to take a maximum of 30 seconds from the time the API server turns off the /readyz endpoint to the removal of the API server instance from the pool. Within the time frame after /readyz returns an error or becomes healthy, the endpoint must have been removed or added. Probing every 5 or 10 seconds, with two successful requests to become healthy and three to become unhealthy, are well-tested values.

2. Application Ingress load balancer: Provides an ingress point for application traffic flowing in from outside the cluster. A working configuration for the Ingress router is required for an OKD cluster.

   Configure the following conditions:

   • Layer 4 load balancing only. This can be referred to as Raw TCP, SSL Passthrough, or SSL Bridge mode. If you use SSL Bridge mode, you must enable Server Name Indication (SNI) for the ingress routes.

   • A connection-based or session-based persistence is recommended, based on the options available and types of applications that will be hosted on the platform.

   If the true IP address of the client can be seen by the application Ingress load balancer, enabling source IP-based session persistence can improve performance for applications that use end-to-end TLS encryption.

   Configure the following ports on both the front and back of the load balancers:

   Table 11. Application Ingress load balancer

   Port	Back-end machines (pool members)	Internal	External	Description
   443	The machines that run the Ingress Controller pods, compute, or worker, by default.	X	X	HTTPS traffic
   80	The machines that run the Ingress Controller pods, compute, or worker, by default.	X	X	HTTP traffic

   If you are deploying a three-node cluster with zero compute nodes, the Ingress Controller pods run on the control plane nodes. In three-node cluster deployments, you must configure your application Ingress load balancer to route HTTP and HTTPS traffic to the control plane nodes.

Example load balancer configuration for user-provisioned clusters

This section provides an example API and application Ingress load balancer configuration that meets the load balancing requirements for user-provisioned clusters. The sample is an /etc/haproxy/haproxy.cfg configuration for an HAProxy load balancer. The example is not meant to provide advice for choosing one load balancing solution over another.

In the example, the same load balancer is used for the Kubernetes API and application ingress traffic. In production scenarios, you can deploy the API and application ingress load balancers separately so that you can scale the load balancer infrastructure for each in isolation.

Sample API and application Ingress load balancer configuration

global
  log         127.0.0.1 local2
  pidfile     /var/run/haproxy.pid
  maxconn     4000
  daemon
defaults
  mode                    http
  log                     global
  option                  dontlognull
  option http-server-close
  option                  redispatch
  retries                 3
  timeout http-request    10s
  timeout queue           1m
  timeout connect         10s
  timeout client          1m
  timeout server          1m
  timeout http-keep-alive 10s
  timeout check           10s
  maxconn                 3000
listen api-server-6443 (1)
  bind *:6443
  mode tcp
  server bootstrap bootstrap.ocp4.example.com:6443 check inter 1s backup (2)
  server master0 master0.ocp4.example.com:6443 check inter 1s
  server master1 master1.ocp4.example.com:6443 check inter 1s
  server master2 master2.ocp4.example.com:6443 check inter 1s
listen machine-config-server-22623 (3)
  bind *:22623
  mode tcp
  server bootstrap bootstrap.ocp4.example.com:22623 check inter 1s backup (2)
  server master0 master0.ocp4.example.com:22623 check inter 1s
  server master1 master1.ocp4.example.com:22623 check inter 1s
  server master2 master2.ocp4.example.com:22623 check inter 1s
listen ingress-router-443 (4)
  bind *:443
  mode tcp
  balance source
  server worker0 worker0.ocp4.example.com:443 check inter 1s
  server worker1 worker1.ocp4.example.com:443 check inter 1s
listen ingress-router-80 (5)
  bind *:80
  mode tcp
  balance source
  server worker0 worker0.ocp4.example.com:80 check inter 1s
  server worker1 worker1.ocp4.example.com:80 check inter 1s