Prerequisites

  • Provision persistent storage for your cluster. To deploy a private image registry, your storage must provide ReadWriteMany access modes.

  • Ensure that your vSphere server has only one datacenter and cluster. If it has multiple datacenters and clusters, it also has multiple default root resource pools, and the worker nodes will not provision during installation.

  • Review details about the OpenShift Container Platform installation and update processes.

  • If you use a firewall, you must configure it to allow the sites that your cluster requires access to.

    Be sure to also review this site list if you are configuring a proxy.

Internet and Telemetry access for OpenShift Container Platform

In OpenShift Container Platform 4.6, you require access to the internet to install your cluster. The Telemetry service, which runs by default to provide metrics about cluster health and the success of updates, also requires internet access. If your cluster is connected to the internet, Telemetry runs automatically, and your cluster is registered to the Red Hat OpenShift Cluster Manager (OCM).

Once you confirm that your Red Hat OpenShift Cluster Manager inventory is correct, either maintained automatically by Telemetry or manually using OCM, use subscription watch to track your OpenShift Container Platform subscriptions at the account or multi-cluster level.

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 content that is required and use it to populate a mirror registry with the packages that you need to install a cluster and generate the installation program. 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.

VMware vSphere infrastructure requirements

You must install the OpenShift Container Platform cluster on a VMware vSphere version 6 or 7 instance that meets the requirements for the components that you use.

Table 1. Minimum supported vSphere version for VMware components
Component Minimum supported versions Description

Hypervisor

vSphere 6.5 and later with HW version 13

This version is the minimum version that Red Hat Enterprise Linux CoreOS (RHCOS) supports. See the Red Hat Enterprise Linux 8 supported hypervisors list.

Networking (NSX-T)

vSphere 6.5U3 or vSphere 6.7U2 and later

vSphere 6.5U3 or vSphere 6.7U2+ are required for OpenShift Container Platform. VMware’s NSX Container Plug-in (NCP) 3.0.2 is certified with OpenShift Container Platform 4.6 and NSX-T 3.x+.

Storage with in-tree drivers

vSphere 6.5 and later

This plug-in creates vSphere storage by using the in-tree storage drivers for vSphere included in OpenShift Container Platform and can be used when vSphere CSI drivers are not available.

Storage with vSphere CSI driver

vSphere 6.7U3 and later

This plug-in creates vSphere storage by using the standard Container Storage Interface. The vSphere CSI driver is provided and supported by VMware.

If you use a vSphere version 6.5 instance, consider upgrading to 6.7U3 or 7.0 before you install OpenShift Container Platform.

You must ensure that the time on your ESXi hosts is synchronized before you install OpenShift Container Platform. See Edit Time Configuration for a Host in the VMware documentation.

A limitation of using VPC is that the Storage Distributed Resource Scheduler (SDRS) is not supported. See vSphere Storage for Kubernetes FAQs in the VMware documentation.

vCenter requirements

Before you install an OpenShift Container Platform cluster on your vCenter that uses infrastructure that the installer provisions, you must prepare your environment.

Required vCenter account privileges

To install an OpenShift Container Platform cluster in a vCenter, the installation program requires access to an account with privileges to read and create the required resources. Using an account that has administrative privileges is the simplest way to access all of the necessary permissions.

A user requires the following privileges to install an OpenShift Container Platform cluster:

  • Datastore

    • Allocate space

    • Browse datastore

    • Low level file operations

    • Remove file

  • Folder

    • Create folder

    • Delete folder

  • vSphere Tagging

    • All privileges

  • Network

    • Assign network

  • Resource

    • Assign virtual machine to resource pool

  • Profile-driven storage

    • All privileges

  • vApp

    • All privileges

  • Virtual machine

    • All privileges

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

Cluster resources

When you deploy an OpenShift Container Platform cluster that uses installer-provisioned infrastructure, the installation program must be able to create several resources in your vCenter instance.

A standard OpenShift Container Platform installation creates the following vCenter resources:

  • 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 OpenShift Container Platform 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

You must use DHCP for the network and ensure that the DHCP server is configured to provide persistent IP addresses and host names to the cluster machines. Additionally, you must create the following networking resources before you install the OpenShift Container Platform cluster:

Required IP Addresses

An installer-provisioned vSphere installation requires two static IP addresses:

  • The API address is used to access the cluster API.

  • The Ingress address is used for cluster ingress traffic.

You must provide these IP addresses to the installation program when you install the OpenShift Container Platform cluster.

DNS records

You must create DNS records for two static IP addresses in the appropriate DNS server for the vCenter instance that hosts your OpenShift Container Platform 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>..

Table 2. Required DNS records
Component Record Description

API VIP

api.<cluster_name>.<base_domain>.

This DNS A/AAAA or CNAME record must point to the load balancer for the control plane machines. This record must be resolvable by both clients external to the cluster and from all the nodes within the cluster.

Ingress VIP

*.apps.<cluster_name>.<base_domain>.

A wildcard DNS A/AAAA or CNAME record that points to the load balancer that targets the machines that run the Ingress router pods, which are the worker nodes by default. This record must be resolvable by both clients external to the cluster and from all the nodes within the cluster.

Generating an SSH private key and adding it to the agent

If you want to perform installation debugging or disaster recovery on your cluster, you must provide an SSH key to both your ssh-agent and the installation program. You can use this key to access the bootstrap machine in a public cluster to troubleshoot installation issues.

In a production environment, you require disaster recovery and debugging.

You can use this key to SSH into the master nodes as the user core. When you deploy the cluster, the key is added to the core user’s ~/.ssh/authorized_keys list.

You must use a local key, not one that you configured with platform-specific approaches such as AWS key pairs.

Procedure
  1. If you do not have an SSH key that is configured for password-less authentication on your computer, create one. For example, on a computer that uses a Linux operating system, run the following command:

    $ ssh-keygen -t rsa -b 4096 -N '' \
        -f <path>/<file_name> (1)
    1 Specify the path and file name, such as ~/.ssh/id_rsa, of the new SSH key.

    Running this command generates an SSH key that does not require a password in the location that you specified.

  2. Start the ssh-agent process as a background task:

    $ eval "$(ssh-agent -s)"
    Example output
    Agent pid 31874
  3. Add your SSH private key to the ssh-agent:

    $ ssh-add <path>/<file_name> (1)
    Example output
    Identity added: /home/<you>/<path>/<file_name> (<computer_name>)
    1 Specify the path and file name for your SSH private key, such as ~/.ssh/id_rsa
Next steps
  • When you install OpenShift Container Platform, provide the SSH public key to the installation program.

Obtaining the installation program

Before you install OpenShift Container Platform, download the installation file on a local computer.

Prerequisites
  • A computer that runs Linux or macOS, with 500 MB of local disk space

Procedure
  1. Access the Infrastructure Provider page on the Red Hat OpenShift Cluster Manager site. If you have a Red Hat account, log in with your credentials. If you do not, create an account.

  2. Navigate to the page for your installation type, download the installation program for your operating system, and place the file in the directory where you will store the installation configuration files.

    The installation program creates several files on the computer that you use to install your cluster. You must keep both the installation program and the files that the installation program creates after you finish installing the cluster.

    Deleting the files created by the installation program does not remove your cluster, even if the cluster failed during installation. To remove your cluster, complete the OpenShift Container Platform uninstallation procedures for your specific cloud provider.

  3. Extract the installation program. For example, on a computer that uses a Linux operating system, run the following command:

    $ tar xvf openshift-install-linux.tar.gz
  4. From the Pull Secret page on the Red Hat OpenShift Cluster Manager site, download your installation pull secret as a .txt file. This pull secret allows you to authenticate with the services that are provided by the included authorities, including Quay.io, which serves the container images for OpenShift Container Platform components.

Adding vCenter root CA certificates to your system trust

Because the installation program requires access to your vCenter’s API, you must add your vCenter’s trusted root CA certificates to your system trust before you install an OpenShift Container Platform cluster.

Procedure
  1. From the vCenter home page, download the vCenter’s root CA certificates. Click Download trusted root CA certificates in the vSphere Web Services SDK section. The <vCenter>/certs/download.zip file downloads.

  2. Extract the compressed file that contains the vCenter root CA certificates. The contents of the compressed file resemble the following file structure:

    certs
    ├── lin
    │   ├── 108f4d17.0
    │   ├── 108f4d17.r1
    │   ├── 7e757f6a.0
    │   ├── 8e4f8471.0
    │   └── 8e4f8471.r0
    ├── mac
    │   ├── 108f4d17.0
    │   ├── 108f4d17.r1
    │   ├── 7e757f6a.0
    │   ├── 8e4f8471.0
    │   └── 8e4f8471.r0
    └── win
        ├── 108f4d17.0.crt
        ├── 108f4d17.r1.crl
        ├── 7e757f6a.0.crt
        ├── 8e4f8471.0.crt
        └── 8e4f8471.r0.crl
    
    3 directories, 15 files
  3. Add the files for your operating system to the system trust. For example, on a Fedora operating system, run the following command:

    # cp certs/lin/* /etc/pki/ca-trust/source/anchors
  4. Update your system trust. For example, on a Fedora operating system, run the following command:

    # update-ca-trust extract

Deploying the cluster

You can install OpenShift Container Platform on a compatible cloud platform.

You can run the create cluster command of the installation program only once, during initial installation.

Prerequisites
  • Obtain the OpenShift Container Platform installation program and the pull secret for your cluster.

Procedure
  1. Run the installation program:

    $ ./openshift-install create cluster --dir=<installation_directory> \ (1)
        --log-level=info (2)
    
    1 For <installation_directory>, specify the directory name to store the files that the installation program creates.
    2 To view different installation details, specify warn, debug, or error instead of info.

    Specify an empty directory. Some installation assets, like bootstrap X.509 certificates have short expiration intervals, so you must not reuse an installation directory. If you want to reuse individual files from another cluster installation, you can copy them into your directory. However, the file names for the installation assets might change between releases. Use caution when copying installation files from an earlier OpenShift Container Platform version.

    Provide values at the prompts:

    1. Optional: Select an SSH key to use to access your cluster machines.

      For production OpenShift Container Platform clusters on which you want to perform installation debugging or disaster recovery, specify an SSH key that your ssh-agent process uses.

    2. Select vsphere as the platform to target.

    3. Specify the name of your vCenter instance.

    4. Specify the user name and password for the vCenter account that has the required permissions to create the cluster.

      The installation program connects to your vCenter instance.

    5. Select the datacenter in your vCenter instance to connect to.

    6. Select the default vCenter datastore to use.

    7. Select the vCenter cluster to install the OpenShift Container Platform cluster in.

    8. Select the network in the vCenter instance that contains the virtual IP addresses and DNS records that you configured.

    9. Enter the virtual IP address that you configured for control plane API access.

    10. Enter the virtual IP address that you configured for cluster ingress.

    11. Enter the base domain. This base domain must be the same one that you used in the DNS records that you configured.

    12. Enter a descriptive name for your cluster. The cluster name must be the same one that you used in the DNS records that you configured.

    13. Paste the pull secret that you obtained from the Pull Secret page on the Red Hat OpenShift Cluster Manager site.

    If the cloud provider account that you configured on your host does not have sufficient permissions to deploy the cluster, the installation process stops, and the missing permissions are displayed.

    When the cluster deployment completes, directions for accessing your cluster, including a link to its web console and credentials for the kubeadmin user, display in your terminal.

    The Ignition config files that the installation program generates contain certificates that expire after 24 hours, which are then renewed at that time. If the cluster is shut down before renewing the certificates and the cluster is later restarted after the 24 hours have elapsed, the cluster automatically recovers the expired certificates. The exception is that you must manually approve the pending node-bootstrapper certificate signing requests (CSRs) to recover kubelet certificates. See the documentation for Recovering from expired control plane certificates for more information.

    You must not delete the installation program or the files that the installation program creates. Both are required to delete the cluster.

Installing the CLI by downloading the binary

You can install the OpenShift CLI (oc) in order to interact with OpenShift Container Platform from a command-line interface. You can install oc on Linux, Windows, or macOS.

If you installed an earlier version of oc, you cannot use it to complete all of the commands in OpenShift Container Platform 4.6. Download and install the new version of oc.

Installing the CLI on Linux

You can install the OpenShift CLI (oc) binary on Linux by using the following procedure.

Procedure
  1. Navigate to the Infrastructure Provider page on the Red Hat OpenShift Cluster Manager site.

  2. Select your infrastructure provider, and, if applicable, your installation type.

  3. In the Command-line interface section, select Linux from the drop-down menu and click Download command-line tools.

  4. Unpack the archive:

    $ tar xvzf <file>
  5. Place the oc binary in a directory that is on your PATH.

    To check your PATH, execute the following command:

    $ echo $PATH

After you install the CLI, it is available using the oc command:

$ oc <command>

Installing the CLI on Windows

You can install the OpenShift CLI (oc) binary on Windows by using the following procedure.

Procedure
  1. Navigate to the Infrastructure Provider page on the Red Hat OpenShift Cluster Manager site.

  2. Select your infrastructure provider, and, if applicable, your installation type.

  3. In the Command-line interface section, select Windows from the drop-down menu and click Download command-line tools.

  4. Unzip the archive with a ZIP program.

  5. Move the oc binary to a directory that is on your PATH.

    To check your PATH, open the command prompt and execute the following command:

    C:\> path

After you install the CLI, it is available using the oc command:

C:\> oc <command>

Installing the CLI on macOS

You can install the OpenShift CLI (oc) binary on macOS by using the following procedure.

Procedure
  1. Navigate to the Infrastructure Provider page on the Red Hat OpenShift Cluster Manager site.

  2. Select your infrastructure provider, and, if applicable, your installation type.

  3. In the Command-line interface section, select MacOS from the drop-down menu and click Download command-line tools.

  4. Unpack and unzip the archive.

  5. Move the oc binary to a directory on your PATH.

    To check your PATH, open a terminal and execute the following command:

    $ echo $PATH

After you install the CLI, it is available using the oc command:

$ oc <command>

Logging in to the cluster

You can log in to your cluster as a default system user by exporting the cluster kubeconfig file. The kubeconfig file contains information about the cluster that is used by the CLI to connect a client to the correct cluster and API server. The file is specific to a cluster and is created during OpenShift Container Platform installation.

Prerequisites
  • Deploy an OpenShift Container Platform cluster.

  • Install the oc CLI.

Procedure
  1. Export the kubeadmin credentials:

    $ export KUBECONFIG=<installation_directory>/auth/kubeconfig (1)
    1 For <installation_directory>, specify the path to the directory that you stored the installation files in.
  2. Verify you can run oc commands successfully using the exported configuration:

    $ oc whoami
    Example output
    system:admin

Creating registry storage

After you install the cluster, you must create storage for the registry Operator.

Image registry removed during installation

On platforms that do not provide shareable object storage, the OpenShift Image Registry Operator bootstraps itself as Removed. This allows openshift-installer to complete installations on these platform types.

After installation, you must edit the Image Registry Operator configuration to switch the managementState from Removed to Managed.

The Prometheus console provides an ImageRegistryRemoved alert, for example:

"Image Registry has been removed. ImageStreamTags, BuildConfigs and DeploymentConfigs which reference ImageStreamTags may not work as expected. Please configure storage and update the config to Managed state by editing configs.imageregistry.operator.openshift.io."

Image registry storage configuration

The image-registry Operator is not initially available for platforms that do not provide default storage. After installation, you must configure your registry to use storage so that the Registry Operator is made available.

Instructions are shown for configuring a PersistentVolume, which is required for production clusters. Where applicable, instructions are shown for configuring an empty directory as the storage location, which is available for only non-production clusters.

Additional instructions are provided for allowing the image registry to use block storage types by using the Recreate rollout strategy during upgrades.

Configuring registry storage for VMware vSphere

As a cluster administrator, following installation you must configure your registry to use storage.

Prerequisites
  • Cluster administrator permissions.

  • A cluster on VMware vSphere.

  • Persistent storage provisioned for your cluster, such as Red Hat OpenShift Container Storage.

    OpenShift Container Platform supports ReadWriteOnce access for image registry storage when you have only one replica. To deploy an image registry that supports high availability with two or more replicas, ReadWriteMany access is required.

  • Must have "100Gi" capacity.

Testing shows issues with using the NFS server on RHEL as storage backend for core services. This includes the OpenShift Container Registry and Quay, Prometheus for monitoring storage, and Elasticsearch for logging storage. Therefore, using RHEL NFS to back PVs used by core services is not recommended.

Other NFS implementations on the marketplace might not have these issues. Contact the individual NFS implementation vendor for more information on any testing that was possibly completed against these OpenShift Container Platform core components.

Procedure
  1. To configure your registry to use storage, change the spec.storage.pvc in the configs.imageregistry/cluster resource.

    When using shared storage, review your security settings to prevent outside access.

  2. Verify that you do not have a registry Pod:

    $ oc get pod -n openshift-image-registry

    If the storage type is emptyDIR, the replica number cannot be greater than 1.

  3. Check the registry configuration:

    $ oc edit configs.imageregistry.operator.openshift.io
    Example output
    storage:
      pvc:
        claim: (1)
    1 Leave the claim field blank to allow the automatic creation of an image-registry-storage PVC.
  4. Check the clusteroperator status:

    $ oc get clusteroperator image-registry

Configuring block registry storage for VMware vSphere

To allow the image registry to use block storage types such as vSphere Virtual Machine Disk (VMDK) during upgrades as a cluster administrator, you can use the Recreate rollout strategy.

Block storage volumes are supported but not recommended for use with image registry on production clusters. An installation where the registry is configured on block storage is not highly available because the registry cannot have more than one replica.

Procedure
  1. To set the image registry storage as a block storage type, patch the registry so that it uses the Recreate rollout strategy and runs with only 1 replica:

    $ oc patch config.imageregistry.operator.openshift.io/cluster --type=merge -p '{"spec":{"rolloutStrategy":"Recreate","replicas":1}}'
  2. Provision the PV for the block storage device, and create a PVC for that volume. The requested block volume uses the ReadWriteOnce (RWO) access mode.

    1. Create a pvc.yaml file with the following contents to define a VMware vSphere PersistentVolumeClaim:

      kind: PersistentVolumeClaim
      apiVersion: v1
      metadata:
        name: image-registry-storage (1)
      spec:
        accessModes:
        - ReadWriteOnce (2)
        resources:
          requests:
            storage: 100Gi (3)
      1 A unique name that represents the PersistentVolumeClaim.
      2 The access mode of the PersistentVolumeClaim. With ReadWriteOnce, the volume can be mounted with read and write permissions by a single node.
      3 The size of the PersistentVolumeClaim.
    2. Create the PersistentVolumeClaim from the file:

      $ oc create -f pvc.yaml
  3. Edit the registry configuration so that it references the correct PVC:

    $ oc edit config.imageregistry.operator.openshift.io -o yaml
    Example output
    storage:
      pvc:
        claim: (1)
    1 Creating a custom PVC allows you to leave the claim field blank for the default automatic creation of an image-registry-storage PVC.

For instructions about configuring registry storage so that it references the correct PVC, see Configuring the registry for vSphere.

Backing up VMware vSphere volumes

OpenShift Container Platform provisions new volumes as independent persistent disks to freely attach and detach the volume on any node in the cluster. As a consequence, it is not possible to back up volumes that use snapshots, or to restore volumes from snapshots. See Snapshot Limitations for more information.

Procedure

To create a backup of persistent volumes:

  1. Stop the application that is using the persistent volume.

  2. Clone the persistent volume.

  3. Restart the application.

  4. Create a backup of the cloned volume.

  5. Delete the cloned volume.