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Preparing to install a cluster using user-provisioned infrastructure

You prepare to install an OKD cluster on vSphere by completing the following steps:

  • Downloading the installation program.

    If you are installing in a disconnected environment, you extract the installation program from the mirrored content. For more information, see Mirroring images for a disconnected installation.

  • Installing the OpenShift CLI (oc).

    If you are installing in a disconnected environment, install oc to the mirror host.

  • Generating an SSH key pair. You can use this key pair to authenticate into the OKD cluster’s nodes after it is deployed.

  • Preparing the user-provisioned infrastructure.

  • Validating DNS resolution.

Obtaining the installation program

Before you install OKD, download the installation file on the host you are using for installation.

Prerequisites

  • You have a computer that runs Linux or macOS, with 500 MB of local disk space.

Procedure

  1. Download installer from https://github.com/openshift/okd/releases

    The installation program creates several files on the computer that you use to install your cluster. You must keep the installation program and the files that the installation program creates after you finish installing the cluster. Both files are required to delete 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 OKD uninstallation procedures for your specific cloud provider.

  2. 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

  3. Download your installation pull secret from Red Hat OpenShift Cluster Manager. 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 OKD components.

    Using a pull secret from Red Hat OpenShift Cluster Manager is not required. You can use a pull secret for another private registry. Or, if you do not need the cluster to pull images from a private registry, you can use {"auths":{"fake":{"auth":"aWQ6cGFzcwo="}}} as the pull secret when prompted during the installation.

    If you do not use the pull secret from Red Hat OpenShift Cluster Manager:

    • Red Hat Operators are not available.

    • The Telemetry and Insights operators do not send data to Red Hat.

    • Content from the Red Hat Ecosystem Catalog Container images registry, such as image streams and Operators, are not available.

Installing the OpenShift CLI by downloading the binary

You can install the OpenShift CLI (oc) to interact with OKD 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 OKD 4. Download and install the new version of oc.

Installing the OpenShift CLI on Linux

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

Procedure

  1. Navigate to https://mirror.openshift.com/pub/openshift-v4/clients/oc/latest/ and choose the folder for your operating system and architecture.

  2. Download oc.tar.gz.

  3. Unpack the archive:

    $ tar xvf <file>

  4. Place the oc binary in a directory that is on your PATH.

    To check your PATH, execute the following command:

    $ echo $PATH
Verification

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

    $ oc <command>

Installing the OpenShift CLI on Windows

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

Procedure

  1. Navigate to https://mirror.openshift.com/pub/openshift-v4/clients/oc/latest/ and choose the folder for your operating system and architecture.

  2. Download oc.zip.

  3. Unzip the archive with a ZIP program.

  4. 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
Verification

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

    C:\> oc <command>

Installing the OpenShift CLI on macOS

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

Procedure

  1. Navigate to https://mirror.openshift.com/pub/openshift-v4/clients/oc/latest/ and choose the folder for your operating system and architecture.

  2. Download oc.tar.gz.

  3. Unpack and unzip the archive.

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

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

    $ echo $PATH
Verification

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

    $ oc <command>

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.

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

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 the Fedora cryptographic libraries that have been submitted to NIST for FIPS 140-2/140-3 Validation on only the x86_64, ppc64le, and s390x architectures, 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
    Identity added: /home/<you>/<path>/<file_name> (<computer_name>)
Next steps

  • When you install OKD, provide the SSH public key to the installation program. If you install a cluster on infrastructure that you provision, you must provide the key to the installation program.

Preparing the user-provisioned infrastructure

Before you install OKD on user-provisioned infrastructure, you must prepare the underlying infrastructure.

This section provides details about the high-level steps required to set up your cluster infrastructure in preparation for an OKD installation. This includes configuring IP networking and network connectivity for your cluster nodes, enabling the required ports through your firewall, and setting up the required DNS and load balancing infrastructure.

After preparation, your cluster infrastructure must meet the requirements outlined in the Requirements for a cluster with user-provisioned infrastructure section.

Prerequisites

  • You have reviewed the OKD 4.x Tested Integrations page.

  • You have reviewed the infrastructure requirements detailed in the Requirements for a cluster with user-provisioned infrastructure section.

Procedure

  1. If you are using DHCP to provide the IP networking configuration to your cluster nodes, configure your DHCP service.

    1. Add persistent IP addresses for the nodes to your DHCP server configuration. In your configuration, match the MAC address of the relevant network interface to the intended IP address for each node.

    2. When you use DHCP to configure IP addressing for the cluster machines, the machines also obtain the DNS server information through DHCP. Define the persistent DNS server address that is used by the cluster nodes through your DHCP server configuration.

      If you are not using a DHCP service, you must provide the IP networking configuration and the address of the DNS server to the nodes at FCOS install time. These can be passed as boot arguments if you are installing from an ISO image. See the Installing FCOS and starting the OKD bootstrap process section for more information about static IP provisioning and advanced networking options.

    3. Define the hostnames of your cluster nodes in your DHCP server configuration. See the Setting the cluster node hostnames through DHCP section for details about hostname considerations.

      If you are not using a DHCP service, the cluster nodes obtain their hostname through a reverse DNS lookup.

  2. Ensure that your network infrastructure provides the required network connectivity between the cluster components. See the Networking requirements for user-provisioned infrastructure section for details about the requirements.

  3. Configure your firewall to enable the ports required for the OKD cluster components to communicate. See Networking requirements for user-provisioned infrastructure section for details about the ports that are required.

    By default, port 1936 is accessible for an OKD cluster, because each control plane node needs access to this port.

    Avoid using the Ingress load balancer to expose this port, because doing so might result in the exposure of sensitive information, such as statistics and metrics, related to Ingress Controllers.

  4. Setup the required DNS infrastructure for your cluster.

    1. Configure DNS name resolution for the Kubernetes API, the application wildcard, the bootstrap machine, the control plane machines, and the compute machines.

    2. Configure reverse DNS resolution for the Kubernetes API, the bootstrap machine, the control plane machines, and the compute machines.

      See the User-provisioned DNS requirements section for more information about the OKD DNS requirements.

  5. Validate your DNS configuration.

    1. From your installation node, run DNS lookups against the record names of the Kubernetes API, the wildcard routes, and the cluster nodes. Validate that the IP addresses in the responses correspond to the correct components.

    2. From your installation node, run reverse DNS lookups against the IP addresses of the load balancer and the cluster nodes. Validate that the record names in the responses correspond to the correct components.

      See the Validating DNS resolution for user-provisioned infrastructure section for detailed DNS validation steps.

  6. Provision the required API and application ingress load balancing infrastructure. See the Load balancing requirements for user-provisioned infrastructure section for more information about the requirements.

Some load balancing solutions require the DNS name resolution for the cluster nodes to be in place before the load balancing is initialized.

Validating DNS resolution for user-provisioned infrastructure

You can validate your DNS configuration before installing OKD on user-provisioned infrastructure.

The validation steps detailed in this section must succeed before you install your cluster.
Prerequisites

  • You have configured the required DNS records for your user-provisioned infrastructure.

Procedure

  1. From your installation node, run DNS lookups against the record names of the Kubernetes API, the wildcard routes, and the cluster nodes. Validate that the IP addresses contained in the responses correspond to the correct components.

    1. Perform a lookup against the Kubernetes API record name. Check that the result points to the IP address of the API load balancer:

      $ dig +noall +answer @<nameserver_ip> api.<cluster_name>.<base_domain> (1)
      1 Replace <nameserver_ip> with the IP address of the nameserver, <cluster_name> with your cluster name, and <base_domain> with your base domain name.
      Example output
      api.ocp4.example.com.		604800	IN	A	192.168.1.5

    2. Perform a lookup against the Kubernetes internal API record name. Check that the result points to the IP address of the API load balancer:

      $ dig +noall +answer @<nameserver_ip> api-int.<cluster_name>.<base_domain>
      Example output
      api-int.ocp4.example.com.		604800	IN	A	192.168.1.5

    3. Test an example *.apps.<cluster_name>.<base_domain> DNS wildcard lookup. All of the application wildcard lookups must resolve to the IP address of the application ingress load balancer:

      $ dig +noall +answer @<nameserver_ip> random.apps.<cluster_name>.<base_domain>
      Example output
      random.apps.ocp4.example.com.		604800	IN	A	192.168.1.5

      In the example outputs, 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.

      You can replace random with another wildcard value. For example, you can query the route to the OKD console:

      $ dig +noall +answer @<nameserver_ip> console-openshift-console.apps.<cluster_name>.<base_domain>
      Example output
      console-openshift-console.apps.ocp4.example.com. 604800 IN	A 192.168.1.5

    4. Run a lookup against the bootstrap DNS record name. Check that the result points to the IP address of the bootstrap node:

      $ dig +noall +answer @<nameserver_ip> bootstrap.<cluster_name>.<base_domain>
      Example output
      bootstrap.ocp4.example.com.		604800	IN	A	192.168.1.96

    5. Use this method to perform lookups against the DNS record names for the control plane and compute nodes. Check that the results correspond to the IP addresses of each node.

  2. From your installation node, run reverse DNS lookups against the IP addresses of the load balancer and the cluster nodes. Validate that the record names contained in the responses correspond to the correct components.

    1. Perform a reverse lookup against the IP address of the API load balancer. Check that the response includes the record names for the Kubernetes API and the Kubernetes internal API:

      $ dig +noall +answer @<nameserver_ip> -x 192.168.1.5
      Example output
      5.1.168.192.in-addr.arpa. 604800	IN	PTR	api-int.ocp4.example.com. (1)
5.1.168.192.in-addr.arpa. 604800	IN	PTR	api.ocp4.example.com. (2)
      1 Provides the record name for the Kubernetes internal API.
      2 Provides the record name for the Kubernetes API.

      A PTR record is not required for the OKD application wildcard. No validation step is needed for reverse DNS resolution against the IP address of the application ingress load balancer.

    2. Perform a reverse lookup against the IP address of the bootstrap node. Check that the result points to the DNS record name of the bootstrap node:

      $ dig +noall +answer @<nameserver_ip> -x 192.168.1.96
      Example output
      96.1.168.192.in-addr.arpa. 604800	IN	PTR	bootstrap.ocp4.example.com.

    3. Use this method to perform reverse lookups against the IP addresses for the control plane and compute nodes. Check that the results correspond to the DNS record names of each node.