Chapter 16. Replacing Controller nodes

Procedure

1. Check the current status of the overcloud stack on the undercloud:

   $ source stackrc
   (undercloud) $ openstack stack list --nested

   The overcloud stack and its subsequent child stacks should have either a CREATE_COMPLETE or UPDATE_COMPLETE.

2. Install the database client tools:

   (undercloud) $ sudo dnf -y install mariadb

3. Configure root user access to the database:

   (undercloud) $ sudo cp /var/lib/config-data/puppet-generated/mysql/root/.my.cnf /root/.

4. Perform a backup of the undercloud databases:

   (undercloud) $ mkdir /home/stack/backup
   (undercloud) $ sudo mysqldump --all-databases --quick --single-transaction | gzip > /home/stack/backup/dump_db_undercloud.sql.gz

5. Check that your undercloud contains 10 GB free storage to accommodate for image caching and conversion when you provision the new node:

   (undercloud) $ df -h

6. Check the status of Pacemaker on the running Controller nodes. For example, if 192.168.0.47 is the IP address of a running Controller node, use the following command to view the Pacemaker status:

   (undercloud) $ ssh heat-admin@192.168.0.47 'sudo pcs status'

   The output shows all services that are running on the existing nodes and that are stopped on the failed node.

7. Check the following parameters on each node of the overcloud MariaDB cluster:

   • wsrep_local_state_comment: Synced

   • wsrep_cluster_size: 2

     Use the following command to check these parameters on each running Controller node. In this example, the Controller node IP addresses are 192.168.0.47 and 192.168.0.46:

     (undercloud) $ for i in 192.168.24.6 192.168.24.7 ; do echo "*** $i ***" ; ssh heat-admin@$i "sudo podman exec \$(sudo podman ps --filter name=galera-bundle -q) mysql -e \"SHOW STATUS LIKE 'wsrep_local_state_comment'; SHOW STATUS LIKE 'wsrep_cluster_size';\""; done

8. Check the RabbitMQ status. For example, if 192.168.0.47 is the IP address of a running Controller node, use the following command to view the RabbitMQ status:

   (undercloud) $ ssh heat-admin@192.168.0.47 "sudo podman exec \$(sudo podman ps -f name=rabbitmq-bundle -q) rabbitmqctl cluster_status"

   The running_nodes key should show only the two available nodes and not the failed node.

9. If fencing is enabled, disable it. For example, if 192.168.0.47 is the IP address of a running Controller node, use the following command to check the status of fencing:

   (undercloud) $ ssh heat-admin@192.168.0.47 "sudo pcs property show stonith-enabled"

   Run the following command to disable fencing:

   (undercloud) $ ssh heat-admin@192.168.0.47 "sudo pcs property set stonith-enabled=false"

10. Check the Compute services are active on the director node:

    (undercloud) $ openstack hypervisor list

    The output should show all non-maintenance mode nodes as up.

11. Ensure all undercloud containers are running:

    (undercloud) $ sudo podman ps

Procedure

1. Connect to the Controller node that you want to replace and become the root user:

   # ssh heat-admin@192.168.0.47
   # sudo su -

   Note

   If the Controller node is unreachable, skip steps 1 and 2 and continue the procedure at step 3 on any working Controller node.

2. Stop the monitor:

   # systemctl stop ceph-mon@<monitor_hostname>

   For example:

   # systemctl stop ceph-mon@overcloud-controller-1

3. Disconnect from the Controller node that you want to replace.

4. Connect to one of the existing Controller nodes.

   # ssh heat-admin@192.168.0.46
   # sudo su -

5. Remove the monitor from the cluster:

   # sudo podman exec -it ceph-mon-controller-0 ceph mon remove overcloud-controller-1

6. On all Controller nodes, remove the v1 and v2 monitor entries from /etc/ceph/ceph.conf. For example, if you remove controller-1, then remove the IPs and hostname for controller-1.

   Before:

   mon host = [v2:172.18.0.21:3300,v1:172.18.0.21:6789],[v2:172.18.0.22:3300,v1:172.18.0.22:6789],[v2:172.18.0.24:3300,v1:172.18.0.24:6789]
   mon initial members = overcloud-controller-2,overcloud-controller-1,overcloud-controller-0

   After:

   mon host = [v2:172.18.0.21:3300,v1:172.18.0.21:6789],[v2:172.18.0.24:3300,v1:172.18.0.24:6789]
   mon initial members = overcloud-controller-2,overcloud-controller-0

   Note

   Director updates the ceph.conf file on the relevant overcloud nodes when you add the replacement Controller node. Normally, director manages this configuration file exclusively and you should not edit the file manually. However, you can edit the file manually if you want to ensure consistency in case the other nodes restart before you add the new node.

7. (Optional) Archive the monitor data and save the archive on another server:

   # mv /var/lib/ceph/mon/<cluster>-<daemon_id> /var/lib/ceph/mon/removed-<cluster>-<daemon_id>

Procedure

1. To view the list of IP addresses for the Controller nodes, run the following command:

   (undercloud) $ openstack server list -c Name -c Networks
   +------------------------+-----------------------+
   | Name                   | Networks              |
   +------------------------+-----------------------+
   | overcloud-compute-0    | ctlplane=192.168.0.44 |
   | overcloud-controller-0 | ctlplane=192.168.0.47 |
   | overcloud-controller-1 | ctlplane=192.168.0.45 |
   | overcloud-controller-2 | ctlplane=192.168.0.46 |
   +------------------------+-----------------------+

2. If the old node is still reachable, log in to one of the remaining nodes and stop pacemaker on the old node. For this example, stop pacemaker on overcloud-controller-1:

   (undercloud) $ ssh heat-admin@192.168.0.47 "sudo pcs status | grep -w Online | grep -w overcloud-controller-1"
   (undercloud) $ ssh heat-admin@192.168.0.47 "sudo pcs cluster stop overcloud-controller-1"

   Note

   In case the old node is physically unavailable or stopped, it is not necessary to perform the previous operation, as pacemaker is already stopped on that node.

3. After you stop Pacemaker on the old node, delete the old node from the pacemaker cluster. The following example command logs in to overcloud-controller-0 to remove overcloud-controller-1:

   (undercloud) $ ssh heat-admin@192.168.0.47 "sudo pcs cluster node remove overcloud-controller-1"

   If the node that that you want to replace is unreachable (for example, due to a hardware failure), run the pcs command with additional --skip-offline and --force options to forcibly remove the node from the cluster:

   (undercloud) $ ssh heat-admin@192.168.0.47 "sudo pcs cluster node remove overcloud-controller-1 --skip-offline --force"

4. After you remove the old node from the pacemaker cluster, remove the node from the list of known hosts in pacemaker:

   (undercloud) $ ssh heat-admin@192.168.0.47 "sudo pcs host deauth overcloud-controller-1"

   You can run this command whether the node is reachable or not.

5. The overcloud database must continue to run during the replacement procedure. To ensure that Pacemaker does not stop Galera during this procedure, select a running Controller node and run the following command on the undercloud with the IP address of the Controller node:

   (undercloud) $ ssh heat-admin@192.168.0.47 "sudo pcs resource unmanage galera-bundle"

Procedure

1. Source the stackrc file:

   $ source ~/stackrc

2. Identify the index of the overcloud-controller-1 node:

   $ INSTANCE=$(openstack server list --name overcloud-controller-1 -f value -c ID)

3. Identify the bare metal node associated with the instance:

   $ NODE=$(openstack baremetal node list -f csv --quote minimal | grep $INSTANCE | cut -f1 -d,)

4. Set the node to maintenance mode:

   $ openstack baremetal node maintenance set $NODE

5. If the Controller node is a virtual node, run the following command on the Controller host to replace the virtual disk from a backup:

   $ cp <VIRTUAL_DISK_BACKUP> /var/lib/libvirt/images/<VIRTUAL_DISK>

   Replace <VIRTUAL_DISK_BACKUP> with the path to the backup of the failed virtual disk, and replace <VIRTUAL_DISK> with the name of the virtual disk that you want to replace.

   If you do not have a backup of the outgoing node, you must use a new virtualized node.

   If the Controller node is a bare metal node, complete the following steps to replace the disk with a new bare metal disk:

   1. Replace the physical hard drive or solid state drive.
   2. Prepare the node with the same configuration as the failed node.

6. List unassociated nodes and identify the ID of the new node:

   $ openstack baremetal node list --unassociated

7. Tag the new node with the control profile:

   (undercloud) $ openstack baremetal node set --property capabilities='profile:control,boot_option:local' 75b25e9a-948d-424a-9b3b-f0ef70a6eacf

Procedure

1. Determine the UUID of the node that you want to remove and store it in the NODEID variable. Ensure that you replace NODE_NAME with the name of the node that you want to remove:

   $ NODEID=$(openstack server list -f value -c ID --name NODE_NAME)

2. To identify the Heat resource ID, enter the following command:

   $ openstack stack resource show overcloud ControllerServers -f json -c attributes | jq --arg NODEID "$NODEID" -c '.attributes.value | keys[] as $k | if .[$k] == $NODEID then "Node index \($k) for \(.[$k])" else empty end'

3. Create the following environment file ~/templates/remove-controller.yaml and include the node index of the Controller node that you want to remove:

   parameters:
     ControllerRemovalPolicies:
       [{'resource_list': ['NODE_INDEX']}]

4. Enter the overcloud deployment command, and include the remove-controller.yaml environment file with any other environment files relevant to your environment:

   (undercloud) $ openstack overcloud deploy --templates \
       -e /home/stack/templates/remove-controller.yaml \
       -e /home/stack/templates/node-info.yaml \
       [OTHER OPTIONS]

   Note

   Include -e ~/templates/remove-controller.yaml only for this instance of the deployment command. Remove this environment file from subsequent deployment operations.

5. Director removes the old node, creates a new node, and updates the overcloud stack. You can check the status of the overcloud stack with the following command:

   (undercloud) $ openstack stack list --nested

6. When the deployment command completes, director shows that the old node is replaced with the new node:

   (undercloud) $ openstack server list -c Name -c Networks
   +------------------------+-----------------------+
   | Name                   | Networks              |
   +------------------------+-----------------------+
   | overcloud-compute-0    | ctlplane=192.168.0.44 |
   | overcloud-controller-0 | ctlplane=192.168.0.47 |
   | overcloud-controller-2 | ctlplane=192.168.0.46 |
   | overcloud-controller-3 | ctlplane=192.168.0.48 |
   +------------------------+-----------------------+

   The new node now hosts running control plane services.

Procedure

1. Log into a Controller node.

2. Enable Pacemaker management of the Galera cluster and start Galera on the new node:

   [heat-admin@overcloud-controller-0 ~]$ sudo pcs resource refresh galera-bundle
   [heat-admin@overcloud-controller-0 ~]$ sudo pcs resource manage galera-bundle

3. Perform a final status check to ensure that the services are running correctly:

   [heat-admin@overcloud-controller-0 ~]$ sudo pcs status

   Note

   If any services have failed, use the pcs resource refresh command to resolve and restart the failed services.

4. Exit to director:

   [heat-admin@overcloud-controller-0 ~]$ exit

5. Source the overcloudrc file so that you can interact with the overcloud:

   $ source ~/overcloudrc

6. Check the network agents in your overcloud environment:

   (overcloud) $ openstack network agent list

7. If any agents appear for the old node, remove them:

   (overcloud) $ for AGENT in $(openstack network agent list --host overcloud-controller-1.localdomain -c ID -f value) ; do openstack network agent delete $AGENT ; done

8. If necessary, add your router to the L3 agent host on the new node. Use the following example command to add a router named r1 to the L3 agent using the UUID 2d1c1dc1-d9d4-4fa9-b2c8-f29cd1a649d4:

   (overcloud) $ openstack network agent add router --l3 2d1c1dc1-d9d4-4fa9-b2c8-f29cd1a649d4 r1

9. Because compute services for the removed node still exist in the overcloud, you must remove them. First, check the compute services for the removed node:

   [stack@director ~]$ source ~/overcloudrc
   (overcloud) $ openstack compute service list --host overcloud-controller-1.localdomain

10. Remove the compute services for the removed node:

    (overcloud) $ for SERVICE in $(openstack compute service list --host overcloud-controller-1.localdomain -c ID -f value ) ; do openstack compute service delete $SERVICE ; done