Chapter 7. Initial steps for overcloud preparation

You must complete some initial steps to prepare for the overcloud upgrade.

7.1. Preparing for overcloud service downtime

The overcloud upgrade process disables the main services at key points. This means you cannot use any overcloud services to create new resources during the upgrade duration. Workloads running in the overcloud remain active during this period, which means instances continue to run through the upgrade duration.

It is important to plan a maintenance window to ensure no users can access the overcloud services during the upgrade duration.

Affected by overcloud upgrade

  • OpenStack Platform services

Unaffected by overcloud upgrade

  • Instances running during the upgrade
  • Ceph Storage OSDs (backend storage for instances)
  • Linux networking
  • Open vSwitch networking
  • Undercloud

7.2. Selecting Compute nodes for upgrade testing

The overcloud upgrade process allows you to either:

  • Upgrade all nodes in a role
  • Individual nodes separately

To ensure a smooth overcloud upgrade process, it is useful to test the upgrade on a few individual Compute nodes in your environment before upgrading all Compute nodes. This ensures no major issues occur during the upgrade while maintaining minimal downtime to your workloads.

Use the following recommendations to help choose test nodes for the upgrade:

  • Select two or three Compute nodes for upgrade testing
  • Select nodes without any critical instances running
  • If necessary, migrate critical instances from the selected test Compute nodes to other Compute nodes

7.3. Validating the pre-upgrade requirements

Run the pre-upgrade validation group to check the pre-upgrade requirements.

Procedure

  1. Source the stackrc file.

    $ source ~/stackrc
  2. Run the openstack tripleo validator run command with the --group pre-upgrade option and include the /usr/libexec/platform-python python runtime environment:

    $ openstack tripleo validator run --group pre-upgrade --python-interpreter /usr/libexec/platform-python
  3. Review the results of the validation report. To view detailed output from a specific validation, run the openstack tripleo validator show run --full command against the UUID of the specific validation from the report:

    $ openstack tripleo validator show run  --full <UUID>
Important

A FAILED validation does not prevent you from deploying or running Red Hat OpenStack Platform. However, a FAILED validation can indicate a potential issue with a production environment.

7.4. Disabling fencing in the overcloud

Before you upgrade the overcloud, ensure that fencing is disabled.

When you upgrade the overcloud, you upgrade each Controller node individually to retain high availability functionality. If fencing is deployed in your environment, the overcloud might detect certain nodes as disabled and attempt fencing operations, which can cause unintended results.

If you have enabled fencing in the overcloud, you must temporarily disable fencing for the duration of the upgrade to avoid any unintended results.

Note

To re-enable fencing in your overcloud, include the fencing.yaml environment file when you run the openstack overcloud upgrade prepare command. Director enables fencing in your overcloud when you create the new Controller node cluster.

Procedure

  1. Log in to the undercloud as the stack user.
  2. Source the stackrc file.

    $ source ~/stackrc
  3. Log in to a Controller node and run the Pacemaker command to disable fencing:

    $ ssh heat-admin@CONTROLLER_IP "sudo pcs property set stonith-enabled=false"

7.5. Creating an overcloud inventory file

Generate an Ansible inventory file of all nodes in your environment with the tripleo-ansible-inventory command.

Procedure

  1. Log in to the undercloud as the stack user.
  2. Source the stackrc file.

    $ source ~/stackrc
  3. Create a static inventory file of all nodes:

    $ tripleo-ansible-inventory --static-yaml-inventory ~/inventory.yaml --stack STACK_NAME

    If you are not using the default overcloud stack name, set your stack name with the --stack STACK NAME option replacing STACK NAME with the name of your stack.

  4. To execute Ansible playbooks on your environment, run the ansible-playbook command and include the full path of the dynamic inventory tool using the -i option. For example:

    (undercloud) $ ansible-playbook -i ~/inventory.yaml PLAYBOOK

7.6. Undercloud node database backup

You can use the backup-and-restore Ansible role to create a backup of the database that runs on the undercloud node and use that backup to recover the state of the database in the event that it becomes corrupted. For more information about backing up the undercloud database, see Creating a database backup of the undercloud node in the Red Hat OpenStack Platform 16.1 Undercloud and Control Plane Back Up and Restore guide.