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documentation.suse.com / Installing RHEL Compute Nodes / Adding a RHEL Compute Node
Applies to SUSE OpenStack Cloud 9

6 Adding a RHEL Compute Node

Adding a RHEL compute node allows you to increase cloud capacity for more virtual machines. These steps will help you add new RHEL compute hosts for this purpose.

6.1 Prerequisites

You need to ensure your input model files are properly setup for RHEL compute host clusters. This must be done during the installation process of your cloud and is discussed further at Chapter 5, Using RHEL as a Compute Node.

6.2 Adding a RHEL compute node

You must have RHEL 7.5 pre-installed on the baremetal host prior to beginning these steps.

  1. Ensure you have RHEL 7.5 pre-installed on your baremetal host.

  2. Log in to the Cloud Lifecycle Manager.

  3. Edit your ~/openstack/my_cloud/definition/data/servers.yml file to include the details about your new compute host.

    For example, if you already had a cluster of three RHEL compute hosts using the RHEL-COMPUTE-ROLE role and need to add a fourth one, you would add your details to the bottom of the file. format. Note IPMI details are not necessary since RHEL has already been preinstalled.

    - id: compute4
      server-group: RACK1

    The role used for new RHEL hosts must match the one used for all existing RHEL hosts.


    Verify that the ip-addr value you set for this host does not conflict with any other IP address in your cloud environment. You can confirm this by checking the ~/openstack/my_cloud/info/address_info.yml file on your Cloud Lifecycle Manager.

  4. In your ~/openstack/my_cloud/definition/data/control_plane.yml file you will need to check the values for member-count, min-count, and max-count. If you specified them, ensure that they match up with your new total node count. For example, if you had previously specified member-count: 3 and are adding a fourth compute node, you will need to change that value to member-count: 4.

  5. Commit the changes to git:

    ardana > git commit -a -m "Add node <name>"
  6. Run the configuration processor and resolve any errors that are indicated:

    ardana > cd ~/openstack/ardana/ansible
    ardana > ansible-playbook -i hosts/localhost config-processor-run.yml
  7. Update your deployment directory:

    ardana > cd ~/openstack/ardana/ansible
    ardana > ansible-playbook -i hosts/localhost ready-deployment.yml

    Before proceeding, review info/server_info.yml to see if the assignment of the node you have added is what you expect. It may not be, as nodes will not be numbered consecutively if any have previously been removed. This is to prevent loss of data; the config processor retains data about removed nodes and keeps their ID numbers from being reallocated.

  8. Look up the value for the new compute node's hostname in ~/scratch/ansible/next/ardana/ansible/hosts/verb_hosts.

    Then, complete the compute host deployment with this playbook:

    ardana > cd ~/scratch/ansible/next/ardana/ansible/
    ardana > ansible-playbook -i hosts/verb_hosts site.yml --tag "generate_hosts_file"
    ardana > ansible-playbook -i hosts/verb_hosts site.yml --limit <hostname>

6.3 Adding a new RHEL compute node to monitoring

If you want to add a new compute node to the monitoring service checks, run this additional playbook to install the necessary components:

ardana > cd ~/scratch/ansible/next/ardana/ansible
ardana > ansible-playbook -i hosts/verb_hosts monasca-deploy.yml --tags "active_ping_checks"