Chapter 10. Scaling Compute nodes with director Operator

Procedure

1. Modify the YAML configuration for the compute OpenStackBaremetalSet and increase count parameter for the resource:

   $ oc patch osbms compute --type=merge --patch '{"spec":{"count":3}}' -n openstack

2. The OpenStackBaremetalSet resource automatically provisions new nodes with the Red Hat Enterprise Linux base operating system. Wait until the provisioning process completes. Check the nodes periodically to determine the readiness of the nodes:

   $ oc get baremetalhosts -n openshift-machine-api
   $ oc get openstackbaremetalset

3. Generate the Ansible Playbooks using OpenStackConfigGenerator, see Configuring overcloud software with the director Operator.

Procedure

1. Access the remote shell for openstackclient:

   $ oc rsh -n openstack openstackclient

2. Identify the Compute node that you want to remove:

   $ openstack compute service list

3. Disable the Compute service on the node to prevent the node from scheduling new instances:

   $ openstack compute service set <hostname> nova-compute --disable

4. Annotate the bare-metal node to prevent Metal³ from starting the node:

   $ oc annotate baremetalhost <node> baremetalhost.metal3.io/detached=true
   $ oc logs --since=1h <metal3-pod> metal3-baremetal-operator | grep -i detach
   $ oc get baremetalhost <node> -o json | jq .status.operationalStatus
   "detached"

   • Replace <node> with the name of the BareMetalHost resource.
   • Replace <metal3-pod> with the name of your metal3 pod.

5. Log in to the Compute node as the root user and shut down the bare-metal node:

   [root@compute-0 ~]# shutdown -h now

   If the Compute node is not accessible, complete the following steps:

   1. Log in to a Controller node as the root user.

   2. If Instance HA is enabled, disable the STONITH device for the Compute node:

      [root@controller-0 ~]# pcs stonith disable <stonith_resource_name>

      • Replace <stonith_resource_name> with the name of the STONITH resource that corresponds to the node. The resource name uses the the format <resource_agent>-<host_mac>. You can find the resource agent and the host MAC address in the FencingConfig section of the fencing.yaml file.
   3. Use IPMI to power off the bare-metal node. For more information, see your hardware vendor documentation.

6. Retrieve the BareMetalHost resource that corresponds to the node that you want to remove:

   $ oc get openstackbaremetalset compute -o json | jq '.status.baremetalHosts | to_entries[] | "\(.key) => \(.value | .hostRef)"'
   "compute-0, openshift-worker-3"
   "compute-1, openshift-worker-4"

7. To change the status of the annotatedForDeletion parameter to true in the OpenStackBaremetalSet resource, annotate the BareMetalHost resource with osp-director.openstack.org/delete-host=true:

   $ oc annotate -n openshift-machine-api bmh/openshift-worker-3 osp-director.openstack.org/delete-host=true --overwrite

8. Optional: Confirm that the annotatedForDeletion status has changed to true in the OpenStackBaremetalSet resource:

   $ oc get openstackbaremetalset compute -o json -n openstack | jq .status
   {
     "baremetalHosts": {
       "compute-0": {
         "annotatedForDeletion": true,
         "ctlplaneIP": "192.168.25.105/24",
         "hostRef": "openshift-worker-3",
         "hostname": "compute-0",
         "networkDataSecretName": "compute-cloudinit-networkdata-openshift-worker-3",
         "provisioningState": "provisioned",
         "userDataSecretName": "compute-cloudinit-userdata-openshift-worker-3"
       },
       "compute-1": {
         "annotatedForDeletion": false,
         "ctlplaneIP": "192.168.25.106/24",
         "hostRef": "openshift-worker-4",
         "hostname": "compute-1",
         "networkDataSecretName": "compute-cloudinit-networkdata-openshift-worker-4",
         "provisioningState": "provisioned",
         "userDataSecretName": "compute-cloudinit-userdata-openshift-worker-4"
       }
     },
     "provisioningStatus": {
       "readyCount": 2,
       "reason": "All requested BaremetalHosts have been provisioned",
       "state": "provisioned"
     }
   }

9. Decrease the count parameter for the compute OpenStackBaremetalSet resource:

   $ oc patch openstackbaremetalset compute --type=merge --patch '{"spec":{"count":1}}' -n openstack

   When you reduce the resource count of the OpenStackBaremetalSet resource, you trigger the corresponding controller to handle the resource deletion, which causes the following actions:

   • Director Operator deletes the corresponding IP reservations from OpenStackIPSet and OpenStackNetConfig for the node.

   • Director Operator flags the IP reservation entry in the OpenStackNet resource as deleted:

     $ oc get osnet ctlplane -o json -n openstack | jq .status.reservations
     {
       "compute-0": {
         "deleted": true,
         "ip": "172.22.0.140"
       },
       "compute-1": {
         "deleted": false,
         "ip": "172.22.0.100"
       },
       "controller-0": {
         "deleted": false,
         "ip": "172.22.0.120"
       },
       "controlplane": {
         "deleted": false,
         "ip": "172.22.0.110"
       },
       "openstackclient-0": {
         "deleted": false,
         "ip": "172.22.0.251"
       }

10. Optional: To make the IP reservations of the deleted OpenStackBaremetalSet resource available for other roles to use, set the value of the spec.preserveReservations parameter to false in the OpenStackNetConfig object.

11. Access the remote shell for openstackclient:

    $ oc rsh openstackclient -n openstack

12. Remove the Compute service entries from the overcloud:

    $ openstack compute service list
    $ openstack compute service delete <service-id>

13. Check the Compute network agents entries in the overcloud and remove them if they exist:

    $ openstack network agent list
    $ for AGENT in $(openstack network agent list --host <scaled-down-node> -c ID -f value) ; do openstack network agent delete $AGENT ; done

14. Exit from openstackclient:

    $ exit