Expanding the cluster

Expanding the cluster

After deploying an installer-provisioned OKD cluster, you can use the following procedures to expand the number of worker nodes. Ensure that each prospective worker node meets the prerequisites.

Expanding the cluster using RedFish Virtual Media involves meeting minimum firmware requirements. See Firmware requirements for installing with virtual media in the Prerequisites section for additional details when expanding the cluster using RedFish Virtual Media.

Preparing the bare metal node

Expanding the cluster requires a DHCP server. Each node must have a DHCP reservation.

Reserving IP addresses so they become static IP addresses

Some administrators prefer to use static IP addresses so that each node’s IP address remains constant in the absence of a DHCP server. To configure static IP addresses with NMState, see “(Optional) Configuring host network interfaces in the install-config.yaml file” in the “Setting up the environment for an OpenShift installation” section for additional details.

Preparing the bare metal node requires executing the following procedure from the provisioner node.

Procedure

Get the oc binary, if needed. It should already exist on the provisioner node.

$ curl -s https://mirror.openshift.com/pub/openshift-v4/clients/ocp/$VERSION/openshift-client-linux-$VERSION.tar.gz | tar zxvf - oc

$ sudo cp oc /usr/local/bin

Power off the bare metal node by using the baseboard management controller (BMC), and ensure it is off.
Retrieve the user name and password of the bare metal node’s baseboard management controller. Then, create base64 strings from the user name and password:
```
$ echo -ne "root" | base64
```
```
$ echo -ne "password" | base64
```

Create a configuration file for the bare metal node.

$ vim bmh.yaml

apiVersion: v1
kind: Secret
metadata:
  name: openshift-worker-<num>-network-config-secret  (1) (2)
type: Opaque
stringData:
 nmstate: |
   routes:
     config:
     - destination: 0.0.0.0/0
       next-hop-address: 192.168.123.1
       next-hop-interface: enp0s4
   dns-resolver:
     config:
       server:
       - 192.168.123.1
   interfaces:
   - name: enp0s4
     state: up
     ipv4:
       address:
       - ip: 192.168.123.16
         prefix-length: 24
       enabled: true
       dhcp: false
---
apiVersion: v1
kind: Secret
metadata:
  name: openshift-worker-<num>-bmc-secret (2)
  namespace: openshift-machine-api
type: Opaque
data:
  username: <base64-of-uid> (3)
  password: <base64-of-pwd> (4)
---
apiVersion: metal3.io/v1alpha1
kind: BareMetalHost
metadata:
  name: openshift-worker-<num> (2)
  namespace: openshift-machine-api
spec:
  online: true
  bootMACAddress: <NIC1-mac-address> (5)
  bmc:
    address: <protocol>://<bmc-ip> (6)
    credentialsName: openshift-worker-<num>-bmc-secret (2)
    disableCertificateVerification: true (7)
    username: <bmc-username> (8)
    password: <bmc-password> (9)
  preprovisioningNetworkDataName: openshift-worker-<num>-network-config-secret  (10) (2)

1	Optional: To configure network for a newly created node, specify the name of the secret that contains the network configuration. Follow the `nmstate` syntax to define the network configuration for your node.
2	Replace `<num>` for the worker number of the bare metal node in the `name` fields, the `credentialsName` field, and the `preprovisioningNetworkDataName` field.
3	Replace `<base64-of-uid>` with the `base64` string of the user name.
4	Replace `<base64-of-pwd>` with the `base64` string of the password.
5	Replace `<NIC1-mac-address>` with the MAC address of the bare metal node’s first NIC. See the “BMC addressing” section for additional BMC configuration options.
6	Replace `<protocol>` with the BMC protocol, such as IPMI, RedFish, or others. Replace `<bmc-ip>` with the IP address of the bare metal node’s baseboard management controller.
7	To skip certificate validation, set `disableCertificateVerification` to `true`.
8	Replace `<bmc-username>` with the `bmc` string of the user name.
9	Replace `<bmc-password>` with the `bmc` string of the password.
10	Optional: Provide the network configuration secret name in the `preprovisioningNetworkDataName` of the `BareMetalHost` CR if you have configured network for the newly created node.

If the MAC address of an existing bare metal node matches the MAC address of a bare metal host that you are attempting to provision, then the Ironic installation will fail. If the host enrollment, inspection, cleaning, or other Ironic steps fail, the Bare Metal Operator retries the installation continuously. See “Diagnosing a host duplicate MAC address” for more information.

Create the bare metal node.

$ oc -n openshift-machine-api create -f bmh.yaml

Example output

secret/openshift-worker-<num>-network-config-secret created
secret/openshift-worker-<num>-bmc-secret created
baremetalhost.metal3.io/openshift-worker-<num> created

Where <num> will be the worker number.

Power up and inspect the bare metal node.

$ oc -n openshift-machine-api get bmh openshift-worker-<num>

Where <num> is the worker node number.

Example output

NAME                    STATE       CONSUMER   ONLINE   ERROR
openshift-worker-<num>  available              true

To allow the worker node to join the cluster, scale the machineset object to the number of the BareMetalHost objects. You can scale nodes either manually or automatically. To scale nodes automatically, use the metal3.io/autoscale-to-hosts annotation for machineset.

Additional resources

Replacing a bare-metal control plane node

Use the following procedure to replace an installer-provisioned OKD control plane node.

If you reuse the BareMetalHost object definition from an existing control plane host, do not leave the externallyProvisioned field set to true.

Existing control plane BareMetalHost objects may have the externallyProvisioned flag set to true if they were provisioned by the OKD installation program.

Prerequisites

You have access to the cluster as a user with the cluster-admin role.

You have taken an etcd backup.

Take an etcd backup before performing this procedure so that you can restore your cluster if you encounter any issues. For more information about taking an etcd backup, see the Additional resources section.

Procedure

Ensure that the Bare Metal Operator is available:

$ oc get clusteroperator baremetal

Example output

NAME        VERSION   AVAILABLE   PROGRESSING   DEGRADED   SINCE   MESSAGE
baremetal   4.10.12   True        False         False      3d15h

Remove the old BareMetalHost and Machine objects:
```
$ oc delete bmh -n openshift-machine-api <host_name>
$ oc delete machine -n openshift-machine-api <machine_name>
```
Replace <host_name> with the name of the host and <machine_name> with the name of the machine. The machine name appears under the CONSUMER field.

After you remove the BareMetalHost and Machine objects, then the machine controller automatically deletes the Node object.

Create the new BareMetalHost object and the secret to store the BMC credentials:

$ cat <<EOF | oc apply -f -
apiVersion: v1
kind: Secret
metadata:
  name: control-plane-<num>-bmc-secret (1)
  namespace: openshift-machine-api
data:
  password: <base64_of_uid> (2)
  username: <base64_of_pwd> (3)
type: Opaque
---
apiVersion: metal3.io/v1alpha1
kind: BareMetalHost
metadata:
  name: control-plane-<num> (1)
  namespace: openshift-machine-api
spec:
  automatedCleaningMode: disabled
  bmc:
    address: <protocol>://<bmc_ip> (4)
    credentialsName: control-plane-<num>-bmc-secret (1)
  bootMACAddress: <NIC1_mac_address> (5)
  bootMode: UEFI
  externallyProvisioned: false
  hardwareProfile: unknown
  online: true
EOF

1	Replace `<num>` for the control plane number of the bare metal node in the `name` fields and the `credentialsName` field.
2	Replace `<base64_of_uid>` with the `base64` string of the user name.
3	Replace `<base64_of_pwd>` with the `base64` string of the password.
4	Replace `<protocol>` with the BMC protocol, such as `redfish`, `redfish-virtualmedia`, `idrac-virtualmedia`, or others. Replace `<bmc_ip>` with the IP address of the bare metal node’s baseboard management controller. For additional BMC configuration options, see “BMC addressing” in the Additional resources section.
5	Replace `<NIC1_mac_address>` with the MAC address of the bare metal node’s first NIC.

After the inspection is complete, the BareMetalHost object is created and available to be provisioned.

View available BareMetalHost objects:

$ oc get bmh -n openshift-machine-api

Example output

NAME                          STATE                    CONSUMER                   ONLINE   ERROR   AGE
control-plane-1.example.com   available                control-plane-1            true             1h10m
control-plane-2.example.com   externally provisioned   control-plane-2            true             4h53m
control-plane-3.example.com   externally provisioned   control-plane-3            true             4h53m
compute-1.example.com         provisioned              compute-1-ktmmx            true             4h53m
compute-1.example.com         provisioned              compute-2-l2zmb            true             4h53m

There are no MachineSet objects for control plane nodes, so you must create a Machine object instead. You can copy the providerSpec from another control plane Machine object.

Create a Machine object:

$ cat <<EOF | oc apply -f -
apiVersion: machine.openshift.io/v1beta1
kind: Machine
metadata:
  annotations:
    metal3.io/BareMetalHost: openshift-machine-api/control-plane-<num> (1)
  labels:
    machine.openshift.io/cluster-api-cluster: control-plane-<num> (1)
    machine.openshift.io/cluster-api-machine-role: master
    machine.openshift.io/cluster-api-machine-type: master
  name: control-plane-<num> (1)
  namespace: openshift-machine-api
spec:
  metadata: {}
  providerSpec:
    value:
      apiVersion: baremetal.cluster.k8s.io/v1alpha1
      customDeploy:
        method: install_coreos
      hostSelector: {}
      image:
        checksum: ""
        url: ""
      kind: BareMetalMachineProviderSpec
      metadata:
        creationTimestamp: null
      userData:
        name: master-user-data-managed
EOF

1	Replace `<num>` for the control plane number of the bare metal node in the `name`, `labels` and `annotations` fields.

To view the BareMetalHost objects, run the following command:

$ oc get bmh -A

Example output

NAME                          STATE                    CONSUMER                   ONLINE   ERROR   AGE
control-plane-1.example.com   provisioned              control-plane-1            true             2h53m
control-plane-2.example.com   externally provisioned   control-plane-2            true             5h53m
control-plane-3.example.com   externally provisioned   control-plane-3            true             5h53m
compute-1.example.com         provisioned              compute-1-ktmmx            true             5h53m
compute-2.example.com         provisioned              compute-2-l2zmb            true             5h53m

After the RHCOS installation, verify that the BareMetalHost is added to the cluster:

$ oc get nodes

Example output

NAME                           STATUS      ROLES     AGE   VERSION
control-plane-1.example.com    available   master    4m2s  v1.18.2
control-plane-2.example.com    available   master    141m  v1.18.2
control-plane-3.example.com    available   master    141m  v1.18.2
compute-1.example.com          available   worker    87m   v1.18.2
compute-2.example.com          available   worker    87m   v1.18.2

After replacement of the new control plane node, the etcd pod running in the new node is in crashloopback status. See “Replacing an unhealthy etcd member” in the Additional resources section for more information.

Additional resources

Preparing to deploy with Virtual Media on the baremetal network

If the provisioning network is enabled and you want to expand the cluster using Virtual Media on the baremetal network, use the following procedure.

Prerequisites

There is an existing cluster with a baremetal network and a provisioning network.

Procedure

Edit the provisioning custom resource (CR) to enable deploying with Virtual Media on the baremetal network:

oc edit provisioning

  apiVersion: metal3.io/v1alpha1
  kind: Provisioning
  metadata:
    creationTimestamp: "2021-08-05T18:51:50Z"
    finalizers:
    - provisioning.metal3.io
    generation: 8
    name: provisioning-configuration
    resourceVersion: "551591"
    uid: f76e956f-24c6-4361-aa5b-feaf72c5b526
  spec:
    preProvisioningOSDownloadURLs: {}
    provisioningDHCPRange: 172.22.0.10,172.22.0.254
    provisioningIP: 172.22.0.3
    provisioningInterface: enp1s0
    provisioningNetwork: Managed
    provisioningNetworkCIDR: 172.22.0.0/24
    provisioningOSDownloadURL: http://192.168.111.1/images/rhcos-<version>.<architecture>.qcow2.gz?sha256=<sha256>
    virtualMediaViaExternalNetwork: true (1)
  status:
    generations:
    - group: apps
      hash: ""
      lastGeneration: 7
      name: metal3
      namespace: openshift-machine-api
      resource: deployments
    - group: apps
      hash: ""
      lastGeneration: 1
      name: metal3-image-cache
      namespace: openshift-machine-api
      resource: daemonsets
    observedGeneration: 8
    readyReplicas: 0

1	Add `virtualMediaViaExternalNetwork: true` to the `provisioning` CR.

If the image URL exists, edit the machineset to use the API VIP address. This step only applies to clusters installed in versions 4.9 or earlier.

oc edit machineset

  apiVersion: machine.openshift.io/v1beta1
  kind: MachineSet
  metadata:
    creationTimestamp: "2021-08-05T18:51:52Z"
    generation: 11
    labels:
      machine.openshift.io/cluster-api-cluster: ostest-hwmdt
      machine.openshift.io/cluster-api-machine-role: worker
      machine.openshift.io/cluster-api-machine-type: worker
    name: ostest-hwmdt-worker-0
    namespace: openshift-machine-api
    resourceVersion: "551513"
    uid: fad1c6e0-b9da-4d4a-8d73-286f78788931
  spec:
    replicas: 2
    selector:
      matchLabels:
        machine.openshift.io/cluster-api-cluster: ostest-hwmdt
        machine.openshift.io/cluster-api-machineset: ostest-hwmdt-worker-0
    template:
      metadata:
        labels:
          machine.openshift.io/cluster-api-cluster: ostest-hwmdt
          machine.openshift.io/cluster-api-machine-role: worker
          machine.openshift.io/cluster-api-machine-type: worker
          machine.openshift.io/cluster-api-machineset: ostest-hwmdt-worker-0
      spec:
        metadata: {}
        providerSpec:
          value:
            apiVersion: baremetal.cluster.k8s.io/v1alpha1
            hostSelector: {}
            image:
              checksum: http:/172.22.0.3:6181/images/rhcos-<version>.<architecture>.qcow2.<md5sum> (1)
              url: http://172.22.0.3:6181/images/rhcos-<version>.<architecture>.qcow2 (2)
            kind: BareMetalMachineProviderSpec
            metadata:
              creationTimestamp: null
            userData:
              name: worker-user-data
  status:
    availableReplicas: 2
    fullyLabeledReplicas: 2
    observedGeneration: 11
    readyReplicas: 2
    replicas: 2

1	Edit the `checksum` URL to use the API VIP address.
2	Edit the `url` URL to use the API VIP address.

Diagnosing a duplicate MAC address when provisioning a new host in the cluster

If the MAC address of an existing bare-metal node in the cluster matches the MAC address of a bare-metal host you are attempting to add to the cluster, the Bare Metal Operator associates the host with the existing node. If the host enrollment, inspection, cleaning, or other Ironic steps fail, the Bare Metal Operator retries the installation continuously. A registration error is displayed for the failed bare-metal host.

You can diagnose a duplicate MAC address by examining the bare-metal hosts that are running in the openshift-machine-api namespace.

Prerequisites

Install an OKD cluster on bare metal.
Install the OKD CLI oc.
Log in as a user with cluster-admin privileges.

Procedure

To determine whether a bare-metal host that fails provisioning has the same MAC address as an existing node, do the following:

Get the bare-metal hosts running in the openshift-machine-api namespace:

$ oc get bmh -n openshift-machine-api

Example output

NAME                 STATUS   PROVISIONING STATUS      CONSUMER
openshift-master-0   OK       externally provisioned   openshift-zpwpq-master-0
openshift-master-1   OK       externally provisioned   openshift-zpwpq-master-1
openshift-master-2   OK       externally provisioned   openshift-zpwpq-master-2
openshift-worker-0   OK       provisioned              openshift-zpwpq-worker-0-lv84n
openshift-worker-1   OK       provisioned              openshift-zpwpq-worker-0-zd8lm
openshift-worker-2   error    registering

To see more detailed information about the status of the failing host, run the following command replacing <bare_metal_host_name> with the name of the host:

$ oc get -n openshift-machine-api bmh <bare_metal_host_name> -o yaml

Example output

...
status:
  errorCount: 12
  errorMessage: MAC address b4:96:91:1d:7c:20 conflicts with existing node openshift-worker-1
  errorType: registration error
...

Provisioning the bare metal node

Provisioning the bare metal node requires executing the following procedure from the provisioner node.

Procedure

Ensure the STATE is available before provisioning the bare metal node.

$  oc -n openshift-machine-api get bmh openshift-worker-<num>

Where <num> is the worker node number.

NAME              STATE     ONLINE ERROR  AGE
openshift-worker  available true          34h

Get a count of the number of worker nodes.

$ oc get nodes

NAME                                                STATUS   ROLES           AGE     VERSION
openshift-master-1.openshift.example.com            Ready    master          30h     v1.24.0
openshift-master-2.openshift.example.com            Ready    master          30h     v1.24.0
openshift-master-3.openshift.example.com            Ready    master          30h     v1.24.0
openshift-worker-0.openshift.example.com            Ready    worker          30h     v1.24.0
openshift-worker-1.openshift.example.com            Ready    worker          30h     v1.24.0

Get the machine set.

$ oc get machinesets -n openshift-machine-api

NAME                                DESIRED   CURRENT   READY   AVAILABLE   AGE
...
openshift-worker-0.example.com      1         1         1       1           55m
openshift-worker-1.example.com      1         1         1       1           55m

Increase the number of worker nodes by one.
```
$ oc scale --replicas=<num> machineset <machineset> -n openshift-machine-api
```
Replace <num> with the new number of worker nodes. Replace <machineset> with the name of the machine set from the previous step.

Check the status of the bare metal node.

$ oc -n openshift-machine-api get bmh openshift-worker-<num>

Where <num> is the worker node number. The STATE changes from ready to provisioning.

NAME                    STATE             CONSUMER                          ONLINE   ERROR
openshift-worker-<num>  provisioning      openshift-worker-<num>-65tjz      true

The provisioning status remains until the OKD cluster provisions the node. This can take 30 minutes or more. After the node is provisioned, the state will change to provisioned.

NAME                    STATE             CONSUMER                          ONLINE   ERROR
openshift-worker-<num>  provisioned       openshift-worker-<num>-65tjz      true

After provisioning completes, ensure the bare metal node is ready.

$ oc get nodes

NAME                                          STATUS   ROLES   AGE     VERSION
openshift-master-1.openshift.example.com      Ready    master  30h     v1.24.0
openshift-master-2.openshift.example.com      Ready    master  30h     v1.24.0
openshift-master-3.openshift.example.com      Ready    master  30h     v1.24.0
openshift-worker-0.openshift.example.com      Ready    worker  30h     v1.24.0
openshift-worker-1.openshift.example.com      Ready    worker  30h     v1.24.0
openshift-worker-<num>.openshift.example.com  Ready    worker  3m27s   v1.24.0

You can also check the kubelet.

$ ssh openshift-worker-<num>

[kni@openshift-worker-<num>]$ journalctl -fu kubelet