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Installing a cluster on bare metal

In OpenShift Container Platform version 4.2, you can install a cluster on bare metal infrastructure that you provision.

While you might be able to follow this procedure to deploy a cluster on virtualized or cloud environments, you must be aware of additional considerations for non-bare metal platforms. Review the information in the guidelines for deploying OpenShift Container Platform on non-tested platforms before you attempt to install an OpenShift Container Platform cluster in such an environment.
Prerequisites

Internet and Telemetry access for OpenShift Container Platform

In OpenShift Container Platform 4.2, 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.

Machine requirements for a cluster with user-provisioned infrastructure

For a cluster that contains user-provisioned infrastructure, you must deploy all of the required machines.

Required machines

The smallest OpenShift Container Platform clusters require the following hosts:

  • One temporary bootstrap machine

  • Three control plane, or master, machines

  • At least two compute machines, which are also known as worker machines

The cluster requires the bootstrap machine to deploy the OpenShift Container Platform cluster on the three control plane machines. You can remove the bootstrap machine after you install the cluster.

To maintain high availability of your cluster, use separate physical hosts for these cluster machines.

The bootstrap, control plane, and compute machines must use the Red Hat Enterprise Linux CoreOS (RHCOS) as the operating system.

Note that RHCOS is based on Red Hat Enterprise Linux 8 and inherits all of its hardware certifications and requirements. See Red Hat Enterprise Linux technology capabilities and limits.

Network connectivity requirements

All the Red Hat Enterprise Linux CoreOS (RHCOS) machines require network in initramfs during boot to fetch Ignition config files from the Machine Config Server. During the initial boot, the machines require a DHCP server in order to establish a network connection to download their Ignition config files.

Minimum resource requirements

Each cluster machine must meet the following minimum requirements:

Machine Operating System vCPU Virtual RAM Storage

Bootstrap

RHCOS

4

16 GB

120 GB

Control plane

RHCOS

4

16 GB

120 GB

Compute

RHCOS or RHEL 7.6

2

8 GB

120 GB

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.

Creating the user-provisioned infrastructure

Before you deploy an OpenShift Container Platform cluster that uses user-provisioned infrastructure, you must create the underlying infrastructure.

Prerequistes
Procedure

  1. Configure DHCP.

  2. Provision the required load balancers.

  3. Configure the ports for your machines.

  4. Configure DNS.

  5. Ensure network connectivity.

Networking requirements for user-provisioned infrastructure

All the Red Hat Enterprise Linux CoreOS (RHCOS) machines require network in initramfs during boot to fetch Ignition config from the Machine Config Server.

During the initial boot, the machines require a DHCP server in order to establish a network connection, which allows them to download their Ignition config files.

It is recommended to use the DHCP server to manage the machines for the cluster long-term. Ensure that the DHCP server is configured to provide persistent IP addresses and host names to the cluster machines.

The Kubernetes API server, which runs on each master node after a successful cluster installation, 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.

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

Table 1. All machines to all machines
Protocol Port Description

ICMP

N/A

Network reachability tests

TCP

9000-9999

Host level services, including the node exporter on ports 9100-9101 and the Cluster Version Operator on port 9099.

10250-10259

The default ports that Kubernetes reserves

10256

openshift-sdn

UDP

4789

VXLAN and GENEVE

6081

VXLAN and GENEVE

9000-9999

Host level services, including the node exporter on ports 9100-9101.

TCP/UDP

30000-32767

Kubernetes NodePort
Table 2. All machines to control plane
Protocol Port Description

TCP

2379-2380

etcd server, peer, and metrics ports

6443

Kubernetes API

Network topology requirements

The infrastructure that you provision for your cluster must meet the following network topology requirements.

OpenShift Container Platform requires all nodes to have internet access to pull images for platform containers and provide telemetry data to Red Hat.
Load balancers

Before you install OpenShift Container Platform, you must provision two layer-4 load balancers. The API requires one load balancer and the default Ingress Controller needs the second load balancer to provide ingress to applications.

Port Machines 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.

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

443

The machines that run the Ingress router pods, compute, or worker, by default.

x

x

HTTPS traffic

80

The machines that run the Ingress router pods, compute, or worker by default.

x

x

HTTP traffic

A working configuration for the Ingress router is required for an OpenShift Container Platform cluster. You must configure the Ingress router after the control plane initializes.

User-provisioned DNS requirements

The following DNS records are required for an OpenShift Container Platform cluster that uses user-provisioned infrastructure. In each record, <cluster_name> is the cluster name and <base_domain> is the cluster base domain that you specify in the install-config.yaml file. A complete DNS record takes the form: <component>.<cluster_name>.<base_domain>..

Table 3. Required DNS records
Component Record Description

Kubernetes API

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.

api-int.<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 from all the nodes within the cluster.

The API server must be able to resolve the worker nodes by the host names that are recorded in Kubernetes. If it cannot resolve the node names, proxied API calls can fail, and you cannot retrieve logs from Pods.

Routes

*.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.

etcd

etcd-<index>.<cluster_name>.<base_domain>.

OpenShift Container Platform requires DNS A/AAAA records for each etcd instance to point to the control plane machines that host the instances. The etcd instances are differentiated by <index> values, which start with 0 and end with n-1, where n is the number of control plane machines in the cluster. The DNS record must resolve to an unicast IPv4 address for the control plane machine, and the records must be resolvable from all the nodes in the cluster.

_etcd-server-ssl._tcp.<cluster_name>.<base_domain>.

For each control plane machine, OpenShift Container Platform also requires a SRV DNS record for etcd server on that machine with priority 0, weight 10 and port 2380. A cluster that uses three control plane machines requires the following records:

# _service._proto.name.                            TTL    class SRV priority weight port target.
_etcd-server-ssl._tcp.<cluster_name>.<base_domain>.  86400 IN    SRV 0        10     2380 etcd-0.<cluster_name>.<base_domain>
_etcd-server-ssl._tcp.<cluster_name>.<base_domain>.  86400 IN    SRV 0        10     2380 etcd-1.<cluster_name>.<base_domain>
_etcd-server-ssl._tcp.<cluster_name>.<base_domain>.  86400 IN    SRV 0        10     2380 etcd-2.<cluster_name>.<base_domain>

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 to the installation program.

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 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)"

Agent pid 31874

  3. Add your SSH private key to the ssh-agent:

    $ ssh-add <path>/<file_name> (1)

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. If you install a cluster on infrastructure that you provision, you must provide this key to your cluster’s machines.

Obtaining the installation program

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

Prerequisites

  • You must install the cluster from a computer that uses Linux or macOS.

  • You need 500 MB of local disk space to download the installation program.

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. You must complete the OpenShift Container Platform uninstallation procedures outlined for your specific cloud provider to remove your cluster entirely.

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

    $ tar xvf <installation_program>.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.

Installing the CLI

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 4.2. 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>

Manually creating the installation configuration file

For installations of OpenShift Container Platform that use user-provisioned infrastructure, you must manually generate your installation configuration file.

Prerequisites

  • Obtain the OpenShift Container Platform installation program and the access token for your cluster.

Procedure

  1. Create an installation directory to store your required installation assets in:

    $ mkdir <installation_directory>

    You must create a 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.

  2. Customize the following install-config.yaml file template and save it in the <installation_directory>.

    You must name this configuration file install-config.yaml.

  3. Back up the install-config.yaml file so that you can use it to install multiple clusters.

    The install-config.yaml file is consumed during the next step of the installation process. You must back it up now.

Sample install-config.yaml file for bare metal

You can customize the install-config.yaml file to specify more details about your OpenShift Container Platform cluster’s platform or modify the values of the required parameters.

apiVersion: v1
baseDomain: example.com (1)
compute:
- hyperthreading: Enabled  (2) (3)
  name: worker
  replicas: 0 (4)
controlPlane:
  hyperthreading: Enabled  (2) (3)
  name: master (3)
  replicas: 3 (5)
metadata:
  name: test (6)
networking:
  clusterNetwork:
  - cidr: 10.128.0.0/14 (7)
    hostPrefix: 23 (8)
  networkType: OpenShiftSDN
  serviceNetwork: (9)
  - 172.30.0.0/16
platform:
  none: {} (10)
pullSecret: '{"auths": ...}' (11)
sshKey: 'ssh-ed25519 AAAA...' (12)
1 The base domain of the cluster. All DNS records must be sub-domains of this base and include the cluster name.
2 The controlPlane section is a single mapping, but the compute section is a sequence of mappings. To meet the requirements of the different data structures, the first line of the compute section must begin with a hyphen, -, and the first line of the controlPlane section must not. Although both sections currently define a single machine pool, it is possible that future versions of OpenShift Container Platform will support defining multiple compute pools during installation. Only one control plane pool is used.
3 Whether to enable or disable simultaneous multithreading, or hyperthreading. By default, simultaneous multithreading is enabled to increase the performance of your machines' cores. You can disable it by setting the parameter value to Disabled. If you disable simultaneous multithreading in some cluster machines, you must disable it in all cluster machines.

If you disable simultaneous multithreading, ensure that your capacity planning accounts for the dramatically decreased machine performance.
4 You must set the value of the replicas parameter to 0. This parameter controls the number of workers that the cluster creates and manages for you, which are functions that the cluster does not perform when you use user-provisioned infrastructure. You must manually deploy worker machines for the cluster to use before you finish installing OpenShift Container Platform.
5 The number of control plane machines that you add to the cluster. Because the cluster uses this values as the number of etcd endpoints in the cluster, the value must match the number of control plane machines that you deploy.
6 The cluster name that you specified in your DNS records.
7 A block of IP addresses from which Pod IP addresses are allocated. This block must not overlap with existing physical networks. These IP addresses are used for the Pod network, and if you need to access the Pods from an external network, configure load balancers and routers to manage the traffic.
8 The subnet prefix length to assign to each individual node. For example, if hostPrefix is set to 23, then each node is assigned a /23 subnet out of the given cidr, which allows for 510 (2^(32 - 23) - 2) pod IPs addresses. If you are required to provide access to nodes from an external network, configure load balancers and routers to manage the traffic.
9 The IP address pool to use for service IP addresses. You can enter only one IP address pool. If you need to access the services from an external network, configure load balancers and routers to manage the traffic.
10 You must set the platform to none. You cannot provide additional platform configuration variables for bare metal infrastructure.
11 The pull secret that you obtained from the Pull Secret page on the Red Hat OpenShift Cluster Manager site. 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.
12 The public portion of the default SSH key for the core user in Red Hat Enterprise Linux CoreOS (RHCOS).

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

Configuring the cluster-wide proxy during installation

Production environments can deny direct access to the Internet and instead have an HTTP or HTTPS proxy available. You can configure a new OpenShift Container Platform cluster to use a proxy by configuring the proxy settings in the install-config.yaml file.

For bare metal installations, if you do not assign node IP addresses from the range that is specified in the networking.machineCIDR field in the install-config.yaml file, you must include them in the proxy.noProxy field.
Prerequisites

  • An existing install-config.yaml file.

  • Review the sites that your cluster requires access to and determine whether any need to bypass the proxy. By default, all cluster egress traffic is proxied, including calls to hosting cloud provider APIs. Add sites to the Proxy object’s spec.noProxy field to bypass the proxy if necessary.

    The Proxy object’s status.noProxy field is populated by default with the instance metadata endpoint (169.254.169.254) and with the values of the networking.machineCIDR, networking.clusterNetwork.cidr, and networking.serviceNetwork fields from your installation configuration.
Procedure

  1. Edit your install-config.yaml file and add the proxy settings. For example:

    apiVersion: v1
baseDomain: my.domain.com
proxy:
  httpProxy: http://<username>:<pswd>@<ip>:<port> (1)
  httpsProxy: http://<username>:<pswd>@<ip>:<port> (2)
  noProxy: example.com (3)
additionalTrustBundle: | (4)
    -----BEGIN CERTIFICATE-----
    <MY_TRUSTED_CA_CERT>
    -----END CERTIFICATE-----
...
    1 A proxy URL to use for creating HTTP connections outside the cluster. The URL scheme must be http.
    2 A proxy URL to use for creating HTTPS connections outside the cluster. If this field is not specified, then httpProxy is used for both HTTP and HTTPS connections. The URL scheme must be http; https is currently not supported.
    3 A comma-separated list of destination domain names, domains, IP addresses, or other network CIDRs to exclude proxying. Preface a domain with . to include all subdomains of that domain. Use * to bypass proxy for all destinations.
    4 If provided, the installation program generates a ConfigMap that is named user-ca-bundle in the openshift-config namespace that contains one or more additional CA certificates that are required for proxying HTTPS connections. The Cluster Network Operator then creates a trusted-ca-bundle ConfigMap that merges these contents with the Red Hat Enterprise Linux CoreOS (RHCOS) trust bundle, and this ConfigMap is referenced in the Proxy object’s trustedCA field. The additionalTrustBundle field is required unless the proxy’s identity certificate is signed by an authority from the RHCOS trust bundle.

    The installation program does not support the proxy readinessEndpoints field.

  2. Save the file and reference it when installing OpenShift Container Platform.

The installation program creates a cluster-wide proxy that is named cluster that uses the proxy settings in the provided install-config.yaml file. If no proxy settings are provided, a cluster Proxy object is still created, but it will have a nil spec.

Only the Proxy object named cluster is supported, and no additional proxies can be created.

Creating the Kubernetes manifest and Ignition config files

Because you must modify some cluster definition files and manually start the cluster machines, you must generate the Kubernetes manifest and Ignition config files that the cluster needs to make its machines.

The Ignition config files that the installation program generates contain certificates that expire after 24 hours. You must complete your cluster installation and keep the cluster running for 24 hours in a non-degraded state to ensure that the first certificate rotation has finished.
Prerequisites

  • Obtain the OpenShift Container Platform installation program.

  • Create the install-config.yaml installation configuration file.

Procedure

  1. Generate the Kubernetes manifests for the cluster:

    $ ./openshift-install create manifests --dir=<installation_directory> (1)

WARNING There are no compute nodes specified. The cluster will not fully initialize without compute nodes.
INFO Consuming "Install Config" from target directory
    1 For <installation_directory>, specify the installation directory that contains the install-config.yaml file you created.

    Because you create your own compute machines later in the installation process, you can safely ignore this warning.

  2. Modify the manifests/cluster-scheduler-02-config.yml Kubernetes manifest file to prevent Pods from being scheduled on the control plane machines:

    1. Open the manifests/cluster-scheduler-02-config.yml file.

    2. Locate the mastersSchedulable parameter and set its value to False.

    3. Save and exit the file.

    Currently, due to a Kubernetes limitation, router Pods running on control plane machines will not be reachable by the ingress load balancer. This step might not be required in a future minor version of OpenShift Container Platform.

  3. Obtain the Ignition config files:

    $ ./openshift-install create ignition-configs --dir=<installation_directory> (1)
    1 For <installation_directory>, specify the same installation directory.

    The following files are generated in the directory:

    .
├── auth
│   ├── kubeadmin-password
│   └── kubeconfig
├── bootstrap.ign
├── master.ign
├── metadata.json
└── worker.ign

Creating Red Hat Enterprise Linux CoreOS (RHCOS) machines

Before you install a cluster on bare metal infrastructure that you provision, you must create RHCOS machines for it to use. Follow either the steps to use an ISO image or network PXE booting to create the machines.

Creating Red Hat Enterprise Linux CoreOS (RHCOS) machines using an ISO image

Before you install a cluster on bare metal infrastructure that you provision, you must create RHCOS machines for it to use. You can use an ISO image to create the machines.

Prerequisites

  • Obtain the Ignition config files for your cluster.

  • Have access to an HTTP server that you can access from your computer and that the machines that you create can access.

Procedure

  1. Upload the control plane, compute, and bootstrap Ignition config files that the installation program created to your HTTP server. Note the URLs of these files.

  2. Obtain the RHCOS images that are required for your preferred method of installing operating system instances from the Product Downloads page on the Red Hat customer portal or the RHCOS image mirror page.

    The RHCOS images might not change with every release of OpenShift Container Platform. You must download images with the highest version that is less than or equal to the OpenShift Container Platform version that you install. Use the image versions that match your OpenShift Container Platform version if they are available.

    You must download the ISO file and the RAW disk file. Those file names resemble the following examples:

    • ISO: rhcos-<version>-<architecture>-installer.iso

    • Compressed metal BIOS: rhcos-<version>-<architecture>-metal-bios.raw.gz

    • Compressed metal UEFI: rhcos-<version>-<architecture>-metal-uefi.raw.gz

  3. Upload either the BIOS or UEFI RHCOS image file to your HTTP server and note its URL.

  4. Use the ISO to start the RHCOS installation. Use one of the following installation options:

    • Burn the ISO image to a disk and boot it directly.

    • Use ISO redirection via a LOM interface.

  5. After the instance boots, press the TAB or E key to edit the kernel command line.

  6. Add the parameters to the kernel command line:

    coreos.inst=yes
coreos.inst.install_dev=sda (1)
coreos.inst.image_url=<image_URL> (2)
coreos.inst.ignition_url=http://example.com/config.ign (3)
    1 Specify the block device of the system to install to.
    2 Specify the URL of the UEFI or BIOS image that you uploaded to your server.
    3 Specify the URL of the Ignition config file for this machine type.

  7. Press Enter to complete the installation. After RHCOS installs, the system reboots. After the system reboots, it applies the Ignition config file that you specified.

  8. Continue to create the machines for your cluster.

    You must create the bootstrap and control plane machines at this time. Because some pods are deployed on compute machines by default, also create at least two compute machines before you install the cluster.

Creating Red Hat Enterprise Linux CoreOS (RHCOS) machines by PXE or iPXE booting

Before you install a cluster on bare metal infrastructure that you provision, you must create RHCOS machines for it to use. You can use PXE or iPXE booting to create the machines.

Prerequisites

  • Obtain the Ignition config files for your cluster.

  • Configure suitable PXE or iPXE infrastructure.

  • Have access to an HTTP server that you can access from your computer.

Procedure

  1. Upload the master, worker, and bootstrap Ignition config files that the installation program created to your HTTP server. Note the URLs of these files.

  2. Obtain the RHCOS ISO image, compressed metal BIOS, kernel and initramfs files from the Product Downloads page on the Red Hat customer portal or the RHCOS image mirror page.

    The RHCOS images might not change with every release of OpenShift Container Platform. You must download images with the highest version that is less than or equal to the OpenShift Container Platform version that you install. Use the image versions that match your OpenShift Container Platform version if they are available.

    The file names contain the OpenShift Container Platform version number. They resemble the following examples:

    • ISO: rhcos-<version>-<architecture>-installer.iso

    • Compressed metal BIOS: rhcos-<version>-<architecture>-metal-bios.raw.gz

    • kernel: rhcos-<version>-<architecture>-installer-kernel

    • initramfs: rhcos-<version>-<architecture>-installer-initramfs.img

  3. Upload the compressed metal BIOS file and the kernel and initramfs files to your HTTP server.

  4. Configure the network boot infrastructure so that the machines boot from their local disks after RHCOS is installed on them.

  5. Configure PXE or iPXE installation for the RHCOS images.

    Modify one of the following example menu entries for your environment and verify that the image and Ignition files are properly accessible:

    • For PXE:

      DEFAULT pxeboot
TIMEOUT 20
PROMPT 0
LABEL pxeboot
    KERNEL http://<HTTP_server>/rhcos-<version>-<architecture>-installer-kernel (1)
    APPEND ip=dhcp rd.neednet=1 initrd=rhcos-<version>-<architecture>-installer-initramfs.img console=tty0 console=ttyS0 coreos.inst=yes coreos.inst.install_dev=sda coreos.inst.image_url=http://<HTTP_server>/rhcos-<version>-<architecture>-metal-bios.raw.gz coreos.inst.ignition_url=http://<HTTP_server>/bootstrap.ign (2) (3)
      1 Specify the location of the kernel file that you uploaded to your HTTP server.
      2 If you use multiple NICs, specify a single interface in the ip option. For example, to use DHCP on a NIC that is named eno1, set ip=eno1:dhcp.
      3 Specify locations of the RHCOS files that you uploaded to your HTTP server. The initrd parameter value is the location of the initramfs file, the coreos.inst.image_url parameter value is the location of the compressed metal BIOS file, and the coreos.inst.ignition_url parameter value is the location of the bootstrap Ignition config file.

    • For iPXE:

      kernel  http://<HTTP_server>/rhcos-<version>-<architecture>-installer-kernel ip=dhcp rd.neednet=1 initrd=http://<HTTP_server>/rhcos-<version>-<architecture>-installer-initramfs.img console=tty0 console=ttyS0 coreos.inst=yes coreos.inst.install_dev=sda coreos.inst.image_url=http://<HTTP_server>/rhcos-<version>-<architecture>-metal-bios.raw.gz coreos.inst.ignition_url=http://<HTTP_server>/bootstrap.ign (1) (2)
initrd http://<HTTP_server>/rhcos-<version>-<architecture>-installer-initramfs.img (3)
boot
      1 Specify locations of the RHCOS files that you uploaded to your HTTP server. The kernel parameter value is the location of the kernel file, the initrd parameter value is the location of the initramfs file, the coreos.inst.image_url parameter value is the location of the compressed metal BIOS file, and the coreos.inst.ignition_url parameter value is the location of the bootstrap Ignition config file.
      2 If you use multiple NICs, specify a single interface in the ip option. For example, to use DHCP on a NIC that is named eno1, set ip=eno1:dhcp.
      3 Specify the location of the initramfs file that you uploaded to your HTTP server.

  6. If you use UEFI, edit the included grub.conf file that is included in the ISO that you downloaded to include the following installation options:

    menuentry 'Install Red Hat Enterprise Linux CoreOS' --class fedora --class gnu-linux --class gnu --class os {
	linux /images/vmlinuz nomodeset rd.neednet=1 coreos.inst=yes coreos.inst.install_dev=sda coreos.inst.image_url=http://<HTTP_server>/rhcos-<version>-<architecture>-metal-uefi.raw.gz coreos.inst.ignition_url=http://<HTTP_server>/bootstrap.ign (1)
	initrd http://<HTTP_server>/rhcos-<version>-<architecture>-installer-initramfs.img (2)
}
    1 For the coreos.inst.image_url parameter value, specify the location of the compressed metal UEFI file that you uploaded to your HTTP server. For the coreos.inst.ignition_url, specify the location of the bootstrap Ignition config file that you uploaded to your HTTP server.
    2 Specify the location of the initramfs file that you uploaded to your HTTP server.

  7. Continue to create the machines for your cluster.

    You must create the bootstrap and control plane machines at this time. Because some pods are deployed on compute machines by default, also create at least two compute machine before you install the cluster.

Creating the cluster

To create the OpenShift Container Platform cluster, you wait for the bootstrap process to complete on the machines that you provisioned by using the Ignition config files that you generated with the installation program.

Prerequisites

  • Create the required infrastructure for the cluster.

  • You obtained the installation program and generated the Ignition config files for your cluster.

  • You used the Ignition config files to create RHCOS machines for your cluster.

  • Your machines have direct internet access.

Procedure

  1. Monitor the bootstrap process:

    $ ./openshift-install --dir=<installation_directory> wait-for bootstrap-complete \ (1)
    --log-level=info (2)
INFO Waiting up to 30m0s for the Kubernetes API at https://api.test.example.com:6443...
INFO API v1.14.6+c4799753c up
INFO Waiting up to 30m0s for the bootstrap-complete event...
    1 For <installation_directory>, specify the path to the directory that you stored the installation files in.
    2 To view different installation details, specify warn, debug, or error instead of info.

    The command succeeds when the Kubernetes API server signals that it has been bootstrapped on the control plane machines.

  2. After bootstrap process is complete, remove the bootstrap machine from the load balancer.

    You must remove the bootstrap machine from the load balancer at this point. You can also remove or reformat the machine itself.

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
system:admin

Approving the CSRs for your machines

When you add machines to a cluster, two pending certificates signing request (CSRs) are generated for each machine that you added. You must confirm that these CSRs are approved or, if necessary, approve them yourself.

Prerequisites

  • You added machines to your cluster.

Procedure

  1. Confirm that the cluster recognizes the machines:

    $ oc get nodes

NAME      STATUS    ROLES   AGE  VERSION
master-0  Ready     master  63m  v1.14.6+c4799753c
master-1  Ready     master  63m  v1.14.6+c4799753c
master-2  Ready     master  64m  v1.14.6+c4799753c
worker-0  NotReady  worker  76s  v1.14.6+c4799753c
worker-1  NotReady  worker  70s  v1.14.6+c4799753c

    The output lists all of the machines that you created.

  2. Review the pending certificate signing requests (CSRs) and ensure that the you see a client and server request with Pending or Approved status for each machine that you added to the cluster:

    $ oc get csr

NAME        AGE     REQUESTOR                                                                   CONDITION
csr-8b2br   15m     system:serviceaccount:openshift-machine-config-operator:node-bootstrapper   Pending (1)
csr-8vnps   15m     system:serviceaccount:openshift-machine-config-operator:node-bootstrapper   Pending
csr-bfd72   5m26s   system:node:ip-10-0-50-126.us-east-2.compute.internal                       Pending (2)
csr-c57lv   5m26s   system:node:ip-10-0-95-157.us-east-2.compute.internal                       Pending
...
    1 A client request CSR.
    2 A server request CSR.

    In this example, two machines are joining the cluster. You might see more approved CSRs in the list.

  3. If the CSRs were not approved, after all of the pending CSRs for the machines you added are in Pending status, approve the CSRs for your cluster machines:

    Because the CSRs rotate automatically, approve your CSRs within an hour of adding the machines to the cluster. If you do not approve them within an hour, the certificates will rotate, and more than two certificates will be present for each node. You must approve all of these certificates. After you approve the initial CSRs, the subsequent node client CSRs are automatically approved by the cluster kube-controller-manager. You must implement a method of automatically approving the kubelet serving certificate requests.

    • To approve them individually, run the following command for each valid CSR:

      $ oc adm certificate approve <csr_name> (1)
      1 <csr_name> is the name of a CSR from the list of current CSRs.

    • To approve all pending CSRs, run the following command:

      $ oc get csr -o go-template='{{range .items}}{{if not .status}}{{.metadata.name}}{{"\n"}}{{end}}{{end}}' | xargs oc adm certificate approve

Initial Operator configuration

After the control plane initializes, you must immediately configure some Operators so that they all become available.

Prerequisites

  • Your control plane has initialized.

Procedure

  1. Watch the cluster components come online:

    $ watch -n5 oc get clusteroperators

NAME                                 VERSION   AVAILABLE   PROGRESSING   DEGRADED   SINCE
authentication                       4.2.0     True        False         False      69s
cloud-credential                     4.2.0     True        False         False      12m
cluster-autoscaler                   4.2.0     True        False         False      11m
console                              4.2.0     True        False         False      46s
dns                                  4.2.0     True        False         False      11m
image-registry                       4.2.0     False       True          False      5m26s
ingress                              4.2.0     True        False         False      5m36s
kube-apiserver                       4.2.0     True        False         False      8m53s
kube-controller-manager              4.2.0     True        False         False      7m24s
kube-scheduler                       4.2.0     True        False         False      12m
machine-api                          4.2.0     True        False         False      12m
machine-config                       4.2.0     True        False         False      7m36s
marketplace                          4.2.0     True        False         False      7m54m
monitoring                           4.2.0     True        False         False      7h54s
network                              4.2.0     True        False         False      5m9s
node-tuning                          4.2.0     True        False         False      11m
openshift-apiserver                  4.2.0     True        False         False      11m
openshift-controller-manager         4.2.0     True        False         False      5m943s
openshift-samples                    4.2.0     True        False         False      3m55s
operator-lifecycle-manager           4.2.0     True        False         False      11m
operator-lifecycle-manager-catalog   4.2.0     True        False         False      11m
service-ca                           4.2.0     True        False         False      11m
service-catalog-apiserver            4.2.0     True        False         False      5m26s
service-catalog-controller-manager   4.2.0     True        False         False      5m25s
storage                              4.2.0     True        False         False      5m30s

  2. Configure the Operators that are not available.

Image registry storage configuration

If the image-registry Operator is not available, you must configure storage for it. Instructions for both configuring a PersistentVolume, which is required for production clusters, and for configuring an empty directory as the storage location, which is available for only non-production clusters, are shown.

Configuring registry storage for bare metal

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

Prerequisites

  • Cluster administrator permissions.

  • A cluster on bare metal.

  • Provision persistent storage for your cluster, such as Red Hat OpenShift Container Storage. To deploy a private image registry, your storage must provide ReadWriteMany access mode.

  • Must have "100Gi" capacity.

Procedure

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

  2. Verify 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. If the storage type is NFS, and you want to scale up the registry Pod by setting replica>1 you must enable the no_wdelay mount option. For example:

    # cat /etc/exports
/mnt/data *(rw,sync,no_wdelay,no_root_squash,insecure,fsid=0)
sh-4.3# exportfs -rv
exporting *:/mnt/data

  3. Check the registry configuration:

    $ oc edit configs.imageregistry.operator.openshift.io

storage:
  pvc:
    claim:

    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 storage for the image registry in non-production clusters

You must configure storage for the image registry Operator. For non-production clusters, you can set the image registry to an empty directory. If you do so, all images are lost if you restart the registry.

Procedure

  • To set the image registry storage to an empty directory:

    $ oc patch configs.imageregistry.operator.openshift.io cluster --type merge --patch '{"spec":{"storage":{"emptyDir":{}}}}'

    Configure this option for only non-production clusters.

    If you run this command before the Image Registry Operator initializes its components, the oc patch command fails with the following error:

    Error from server (NotFound): configs.imageregistry.operator.openshift.io "cluster" not found

    Wait a few minutes and run the command again.

Completing installation on user-provisioned infrastructure

After you complete the Operator configuration, you can finish installing the cluster on infrastructure that you provide.

Prerequisites

  • Your control plane has initialized.

  • You have completed the initial Operator configuration.

Procedure

  1. Confirm that all the cluster components are online:

    $ watch -n5 oc get clusteroperators

NAME                                 VERSION   AVAILABLE   PROGRESSING   DEGRADED   SINCE
authentication                       4.2.0     True        False         False      10m
cloud-credential                     4.2.0     True        False         False      22m
cluster-autoscaler                   4.2.0     True        False         False      21m
console                              4.2.0     True        False         False      10m
dns                                  4.2.0     True        False         False      21m
image-registry                       4.2.0     True        False         False      16m
ingress                              4.2.0     True        False         False      16m
kube-apiserver                       4.2.0     True        False         False      19m
kube-controller-manager              4.2.0     True        False         False      18m
kube-scheduler                       4.2.0     True        False         False      22m
machine-api                          4.2.0     True        False         False      22m
machine-config                       4.2.0     True        False         False      18m
marketplace                          4.2.0     True        False         False      18m
monitoring                           4.2.0     True        False         False      18m
network                              4.2.0     True        False         False      16m
node-tuning                          4.2.0     True        False         False      21m
openshift-apiserver                  4.2.0     True        False         False      21m
openshift-controller-manager         4.2.0     True        False         False      17m
openshift-samples                    4.2.0     True        False         False      14m
operator-lifecycle-manager           4.2.0     True        False         False      21m
operator-lifecycle-manager-catalog   4.2.0     True        False         False      21m
service-ca                           4.2.0     True        False         False      21m
service-catalog-apiserver            4.2.0     True        False         False      16m
service-catalog-controller-manager   4.2.0     True        False         False      16m
storage                              4.2.0     True        False         False      16m

    When all of the cluster Operators are AVAILABLE, you can complete the installation.

  2. Monitor for cluster completion:

    $ ./openshift-install --dir=<installation_directory> wait-for install-complete (1)
INFO Waiting up to 30m0s for the cluster to initialize...
    1 For <installation_directory>, specify the path to the directory that you stored the installation files in.

    The command succeeds when the Cluster Version Operator finishes deploying the OpenShift Container Platform cluster from Kubernetes API server.

    The Ignition config files that the installation program generates contain certificates that expire after 24 hours. You must keep the cluster running for 24 hours in a non-degraded state to ensure that the first certificate rotation has finished.

  3. Confirm that the Kubernetes API server is communicating with the Pods.

    1. To view a list of all Pods, use the following command:

      $ oc get pods --all-namespaces

NAMESPACE                         NAME                                            READY   STATUS      RESTARTS   AGE
openshift-apiserver-operator      openshift-apiserver-operator-85cb746d55-zqhs8   1/1     Running     1          9m
openshift-apiserver               apiserver-67b9g                                 1/1     Running     0          3m
openshift-apiserver               apiserver-ljcmx                                 1/1     Running     0          1m
openshift-apiserver               apiserver-z25h4                                 1/1     Running     0          2m
openshift-authentication-operator authentication-operator-69d5d8bf84-vh2n8        1/1     Running     0          5m
...

    2. View the logs for a Pod that is listed in the output of the previous command by using the following command:

      $ oc logs <pod_name> -n <namespace> (1)
      1 Specify the Pod name and namespace, as shown in the output of the previous command.

      If the Pod logs display, the Kubernetes API server can communicate with the cluster machines.

Next steps