Chapter 8. Scaling the Environment

The Red Hat Enterprise Linux OpenStack Platform installer not only deploys multi-node OpenStack environments but also provides a means to scale such environments. Scaling an environment is a simple process that only requires adding more hosts to deployment roles.
This chapter steps through the process of adding a Compute node to an existing environment.

8.1. Discovering a New Host for Scaling

Scaling your environment also uses the PXE-based discovery service to add new hosts. Users run a PXE boot on their bare metal hosts over the provisioning subnet (e.g. 10.1.1.0/24) and the installer automatically includes them in the list of available hosts.

Procedure 8.1. Adding a Host via Discovery

  1. Start the host and elect to start over the network from the boot options menu. This starts the host using the PXE service the installer provides.
  2. Select Foreman Discovery from the PXE boot options menu. The host starts into the Foreman Discovery screen and is automatically registered in the installer.
    The Foreman Discovery screen

    Figure 8.1. The Foreman Discovery Screen

  3. Log in to the user interface and confirm that the host has been registered:
    1. Click HostsDiscovered hosts.
    2. Click the name of the newly registered host to open the details page for the host, and review the details.
      The discovered host details page

      Figure 8.2. The Discovered Host Details Page

The host is automatically included in the list of unassigned hosts when you assign hosts to a deployment. The host is also automatically added to the discovery environment, which is the default Puppet environment for discovered hosts. This environment acts as a holding area that identifies hosts that have not yet been provisioned.