Post-installation configuration - Deploying installer-provisioned clusters on bare metal | Installing

Configuring NTP for disconnected clusters (optional)
Enabling a provisioning network after installation
Configuring an external load balancer

After successfully deploying an installer-provisioned cluster, consider the following post-installation procedures.

Configuring NTP for disconnected clusters (optional)

OpenShift Container Platform installs the chrony Network Time Protocol (NTP) service on the cluster nodes. Use the following procedure to configure NTP servers on the control plane nodes and configure worker nodes as NTP clients of the control plane nodes after a successful deployment.

OpenShift Container Platform nodes must agree on a date and time to run properly. When worker nodes retrieve the date and time from the NTP servers on the control plane nodes, it enables the installation and operation of clusters that are not connected to a routable network and thereby do not have access to a higher stratum NTP server.

Procedure

Create a Butane config, 99-master-chrony-conf-override.bu, including the contents of the chrony.conf file for the control plane nodes.

See "Creating machine configs with Butane" for information about Butane.

Butane config example

variant: openshift
version: 4.8.0
metadata:
  name: 99-master-chrony-conf-override
  labels:
    machineconfiguration.openshift.io/role: master
storage:
  files:
    - path: /etc/chrony.conf
      mode: 0644
      overwrite: true
      contents:
        inline: |
          # Use public servers from the pool.ntp.org project.
          # Please consider joining the pool (https://www.pool.ntp.org/join.html).

          # The Machine Config Operator manages this file
          server openshift-master-0.<cluster-name>.<domain> iburst (1)
          server openshift-master-1.<cluster-name>.<domain> iburst
          server openshift-master-2.<cluster-name>.<domain> iburst

          stratumweight 0
          driftfile /var/lib/chrony/drift
          rtcsync
          makestep 10 3
          bindcmdaddress 127.0.0.1
          bindcmdaddress ::1
          keyfile /etc/chrony.keys
          commandkey 1
          generatecommandkey
          noclientlog
          logchange 0.5
          logdir /var/log/chrony

          # Configure the control plane nodes to serve as local NTP servers
          # for all worker nodes, even if they are not in sync with an
          # upstream NTP server.

          # Allow NTP client access from the local network.
          allow all
          # Serve time even if not synchronized to a time source.
          local stratum 3 orphan

1	You must replace `<cluster-name>` with the name of the cluster and replace `<domain>` with the fully qualified domain name.

Use Butane to generate a MachineConfig object file, 99-master-chrony-conf-override.yaml, containing the configuration to be delivered to the control plane nodes:
```
$ butane 99-master-chrony-conf-override.bu -o 99-master-chrony-conf-override.yaml
```

Create a Butane config, 99-worker-chrony-conf-override.bu, including the contents of the chrony.conf file for the worker nodes that references the NTP servers on the control plane nodes.

Butane config example

variant: openshift
version: 4.8.0
metadata:
  name: 99-worker-chrony-conf-override
  labels:
    machineconfiguration.openshift.io/role: worker
storage:
  files:
    - path: /etc/chrony.conf
      mode: 0644
      overwrite: true
      contents:
        inline: |
          # The Machine Config Operator manages this file.
          server openshift-master-0.<cluster-name>.<domain> iburst (1)
          server openshift-master-1.<cluster-name>.<domain> iburst
          server openshift-master-2.<cluster-name>.<domain> iburst

          stratumweight 0
          driftfile /var/lib/chrony/drift
          rtcsync
          makestep 10 3
          bindcmdaddress 127.0.0.1
          bindcmdaddress ::1
          keyfile /etc/chrony.keys
          commandkey 1
          generatecommandkey
          noclientlog
          logchange 0.5
          logdir /var/log/chrony

1	You must replace `<cluster-name>` with the name of the cluster and replace `<domain>` with the fully qualified domain name.

Use Butane to generate a MachineConfig object file, 99-worker-chrony-conf-override.yaml, containing the configuration to be delivered to the worker nodes:
```
$ butane 99-worker-chrony-conf-override.bu -o 99-worker-chrony-conf-override.yaml
```

Apply the 99-master-chrony-conf-override.yaml policy to the control plane nodes.

$ oc apply -f 99-master-chrony-conf-override.yaml

Example output

machineconfig.machineconfiguration.openshift.io/99-master-chrony-conf-override created

Apply the 99-worker-chrony-conf-override.yaml policy to the worker nodes.

$ oc apply -f 99-worker-chrony-conf-override.yaml

Example output

machineconfig.machineconfiguration.openshift.io/99-worker-chrony-conf-override created

Check the status of the applied NTP settings.
```
$ oc describe machineconfigpool
```

Enabling a provisioning network after installation

The assisted installer and installer-provisioned installation for bare metal clusters provide the ability to deploy a cluster without a provisioning network. This capability is for scenarios such as proof-of-concept clusters or deploying exclusively with Redfish virtual media when each node’s baseboard management controller is routable via the baremetal network.

In OpenShift Container Platform 4.8 and later, you can enable a provisioning network after installation using the Cluster Baremetal Operator (CBO).

Prerequisites

A dedicated physical network must exist, connected to all worker and control plane nodes.
You must isolate the native, untagged physical network.
The network cannot have a DHCP server when the provisioningNetwork configuration setting is set to Managed.
You can omit the provisioningInterface setting in OpenShift Container Platform 4.9 to use the bootMACAddress configuration setting.

Procedure

When setting the provisioningInterface setting, first identify the provisioning interface name for the cluster nodes. For example, eth0 or eno1.
Enable the Preboot eXecution Environment (PXE) on the provisioning network interface of the cluster nodes.
Retrieve the current state of the provisioning network and save it to a provisioning custom resource (CR) file:
```
$ oc get provisioning -o yaml > enable-provisioning-nw.yaml
```

Modify the provisioning CR file:

$ vim ~/enable-provisioning-nw.yaml

Scroll down to the provisioningNetwork configuration setting and change it from Disabled to Managed. Then, add the provisioningOSDownloadURL, provisioningIP, provisioningNetworkCIDR, provisioningDHCPRange, provisioningInterface, and watchAllNameSpaces configuration settings after the provisioningNetwork setting. Provide appropriate values for each setting.

apiVersion: v1
items:
- apiVersion: metal3.io/v1alpha1
  kind: Provisioning
  metadata:
    name: provisioning-configuration
  spec:
    provisioningNetwork: (1)
    provisioningOSDownloadURL: (2)
    provisioningIP: (3)
    provisioningNetworkCIDR: (4)
    provisioningDHCPRange: (5)
    provisioningInterface: (6)
    watchAllNameSpaces: (7)

1	The `provisioningNetwork` is one of `Managed`, `Unmanaged`, or `Disabled`. When set to `Managed`, Metal3 manages the provisioning network and the CBO deploys the Metal3 pod with a configured DHCP server. When set to `Unmanaged`, the system administrator configures the DHCP server manually.
2	The `provisioningOSDownloadURL` is a valid HTTPS URL with a valid sha256 checksum that enables the Metal3 pod to download a qcow2 operating system image ending in `.qcow2.gz` or `.qcow2.xz`. This field is required whether the provisioning network is `Managed`, `Unmanaged`, or `Disabled`. For example: `http://192.168.0.1/images/rhcos-<version>.x86_64.qcow2.gz?sha256=<sha>`.
3	The `provisioningIP` is the static IP address that the DHCP server and ironic use to provision the network. This static IP address must be within the `provisioning` subnet, and outside of the DHCP range. If you configure this setting, it must have a valid IP address even if the `provisioning` network is `Disabled`. The static IP address is bound to the metal3 pod. If the metal3 pod fails and moves to another server, the static IP address also moves to the new server.
4	The Classless Inter-Domain Routing (CIDR) address. If you configure this setting, it must have a valid CIDR address even if the `provisioning` network is `Disabled`. For example: `192.168.0.1/24`.
5	The DHCP range. This setting is only applicable to a `Managed` provisioning network. Omit this configuration setting if the `provisioning` network is `Disabled`. For example: `192.168.0.64, 192.168.0.253`.
6	The NIC name for the `provisioning` interface on cluster nodes. The `provisioningInterface` setting is only applicable to `Managed` and `Unmanaged` provisioning networks. Omit the `provisioningInterface` configuration setting if the `provisioning` network is `Disabled`. Omit the `provisioningInterface` configuration setting to use the `bootMACAddress` configuration setting instead.
7	Set this setting to `true` if you want metal3 to watch namespaces other than the default `openshift-machine-api` namespace. The default value is `false`.

Save the changes to the provisioning CR file.
Apply the provisioning CR file to the cluster:
```
$ oc apply -f enable-provisioning-nw.yaml
```

Configuring an external load balancer

You can configure an OpenShift Container Platform cluster to use an external load balancer in place of the default load balancer.

Prerequisites

On your load balancer, TCP over ports 6443, 443, and 80 must be available to any users of your system.
Load balance the API port, 6443, between each of the control plane nodes.
Load balance the application ports, 443 and 80, between all of the compute nodes.
On your load balancer, port 22623, which is used to serve ignition startup configurations to nodes, is not exposed outside of the cluster.
Your load balancer must be able to access every machine in your cluster. Methods to allow this access include:
- Attaching the load balancer to the cluster’s machine subnet.
- Attaching floating IP addresses to machines that use the load balancer.

External load balancing services and the control plane nodes must run on the same L2 network, and on the same VLAN when using VLANs to route traffic between the load balancing services and the control plane nodes.

Procedure

Enable access to the cluster from your load balancer on ports 6443, 443, and 80.

As an example, note this HAProxy configuration:

A section of a sample HAProxy configuration

...
listen my-cluster-api-6443
    bind 0.0.0.0:6443
    mode tcp
    balance roundrobin
    server my-cluster-master-2 192.0.2.2:6443 check
    server my-cluster-master-0 192.0.2.3:6443 check
    server my-cluster-master-1 192.0.2.1:6443 check
listen my-cluster-apps-443
        bind 0.0.0.0:443
        mode tcp
        balance roundrobin
        server my-cluster-worker-0 192.0.2.6:443 check
        server my-cluster-worker-1 192.0.2.5:443 check
        server my-cluster-worker-2 192.0.2.4:443 check
listen my-cluster-apps-80
        bind 0.0.0.0:80
        mode tcp
        balance roundrobin
        server my-cluster-worker-0 192.0.2.7:80 check
        server my-cluster-worker-1 192.0.2.9:80 check
        server my-cluster-worker-2 192.0.2.8:80 check

Add records to your DNS server for the cluster API and apps over the load balancer. For example:

<load_balancer_ip_address> api.<cluster_name>.<base_domain>
<load_balancer_ip_address> apps.<cluster_name>.<base_domain>

From a command line, use curl to verify that the external load balancer and DNS configuration are operational.

Verify that the cluster API is accessible:

$ curl https://<loadbalancer_ip_address>:6443/version --insecure

If the configuration is correct, you receive a JSON object in response:

{
  "major": "1",
  "minor": "11+",
  "gitVersion": "v1.11.0+ad103ed",
  "gitCommit": "ad103ed",
  "gitTreeState": "clean",
  "buildDate": "2019-01-09T06:44:10Z",
  "goVersion": "go1.10.3",
  "compiler": "gc",
  "platform": "linux/amd64"
}

Verify that cluster applications are accessible:

You can also verify application accessibility by opening the OpenShift Container Platform console in a web browser.

$ curl http://console-openshift-console.apps.<cluster_name>.<base_domain> -I -L --insecure

If the configuration is correct, you receive an HTTP response:

HTTP/1.1 302 Found
content-length: 0
location: https://console-openshift-console.apps.<cluster-name>.<base domain>/
cache-control: no-cacheHTTP/1.1 200 OK
referrer-policy: strict-origin-when-cross-origin
set-cookie: csrf-token=39HoZgztDnzjJkq/JuLJMeoKNXlfiVv2YgZc09c3TBOBU4NI6kDXaJH1LdicNhN1UsQWzon4Dor9GWGfopaTEQ==; Path=/; Secure
x-content-type-options: nosniff
x-dns-prefetch-control: off
x-frame-options: DENY
x-xss-protection: 1; mode=block
date: Tue, 17 Nov 2020 08:42:10 GMT
content-type: text/html; charset=utf-8
set-cookie: 1e2670d92730b515ce3a1bb65da45062=9b714eb87e93cf34853e87a92d6894be; path=/; HttpOnly; Secure; SameSite=None
cache-control: private

Installer-provisioned post-installation configuration

Configuring NTP for disconnected clusters (optional)

Enabling a provisioning network after installation

Configuring an external load balancer