Chapter 7. Initial steps for overcloud preparation

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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 control plane services at key points. You cannot use any overcloud services to create new resources when these key points are reached. Workloads that are running in the overcloud remain active during the upgrade process, which means instances continue to run during the upgrade of the control plane. During an upgrade of Compute nodes, these workloads can be live migrated to Compute nodes that are already upgraded.

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

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. Creating an overcloud inventory file

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


  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

7.4. Validating the pre-upgrade requirements

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

For more information about the Red Hat OpenStack Platform (RHOSP) validation framework, see Using the validation framework in the Director Installation and Usage guide.


  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 -i inventory.yaml
  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>

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

7.5. 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.


  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"
  4. In the fencing.yaml environment file, set the EnableFencing parameter to false to ensure that fencing stays disabled during the upgrade process.

7.6. Checking custom Puppet parameters

If you use the ExtraConfig interfaces for customizations of Puppet parameters, Puppet might report duplicate declaration errors during the upgrade. This is due to changes in the interfaces provided by the puppet modules themselves.

This procedure shows how to check for any custom ExtraConfig hieradata parameters in your environment files.


  1. Select an environment file and the check if it has an ExtraConfig parameter:

    $ grep ExtraConfig ~/templates/custom-config.yaml
  2. If the results show an ExtraConfig parameter for any role (e.g. ControllerExtraConfig) in the chosen file, check the full parameter structure in that file.
  3. If the parameter contains any puppet Hierdata with a SECTION/parameter syntax followed by a value, it might have been been replaced with a parameter with an actual Puppet class. For example:

            value: 'true'
  4. Check the director’s Puppet modules to see if the parameter now exists within a Puppet class. For example:

    $ grep dnsmasq_local_resolv

    If so, change to the new interface.

  5. The following are examples to demonstrate the change in syntax:

    • Example 1:

              value: 'true'

      Changes to:

          neutron::agents::dhcp::dnsmasq_local_resolv: true
    • Example 2:

              value: '32'

      Changes to:

          oslo::messaging::rabbit::rabbit_qos_prefetch_count: '32'

7.7. 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 Backing up and restoring the undercloud and control plane nodes guide.

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