(DEPRECATED) Installing a Undercloud Minion


The minion functionality is deprecated starting in Wallaby.


This is optional functionality that is helpful for large scale related deployments.


The minion functionality is only available starting from the Train cycle.

The undercloud can be scaled horizontally by installing and configuring undercloud minions. The minions can expand the number of heat-engine and ironic-conductors available the overall undercloud installation. The undercloud minions can be added and removed as necessary to scale processing during a deployment.

Installation Steps


The minion requires an undercloud has been installed. The undercloud installation process has two output files that we will need to install the minion.

  1. Log in to your machine (baremetal or VM) where you want to install the minion as a non-root user (such as the stack user):

    ssh <non-root-user>@<minion-machine>


    If you don’t have a non-root user created yet, log in as root and create one with following commands:

    sudo useradd stack
    sudo passwd stack  # specify a password
    echo "stack ALL=(root) NOPASSWD:ALL" | sudo tee -a /etc/sudoers.d/stack
    sudo chmod 0440 /etc/sudoers.d/stack
    su - stack


    The minion is intended to work correctly with SELinux enforcing. Installations with the permissive/disabled SELinux are not recommended. The minion_enable_selinux config option controls that setting.


    vlan tagged interfaces must follow the if_name.vlan_id convention, like for example: eth0.vlan100 or bond0.vlan120.

  2. Enable needed repositories:


    Enable optional repo:

    sudo yum install -y yum-utils
    sudo yum-config-manager --enable rhelosp-rhel-7-server-opt


    Python3 is required for current releases of OpenStack which is supported on CentOS Stream 9.

    1. Download and install the python-tripleo-repos RPM from the appropriate RDO repository

      CentOS Stream 9

      Current Centos 9 RDO repository.

      sudo dnf install -y https://trunk.rdoproject.org/centos9/component/tripleo/current/python3-tripleo-repos-<version>.el9.noarch.rpm


      tripleo-repos removes any repositories that it manages before each run. This means all repositories must be specified in a single tripleo-repos call. As an example, the correct way to install the current and ceph repos is to run tripleo-repos current ceph, not two separate calls.

    1. Run tripleo-repos to install the appropriate repositories. The option below will enable the latest master TripleO packages, the latest promoted packages for all other OpenStack services and dependencies and the latest stable Ceph packages. There are other repository configurations available in tripleo-repos, see its --help output for details.

      sudo -E tripleo-repos current-tripleo-dev ceph
  1. Install the TripleO CLI, which will pull in all other necessary packages as dependencies:

    sudo yum install -y python-tripleoclient
  2. Copy the tripleo-undercloud-outputs.yaml and tripleo-undercloud-passwords.yaml from the undercloud to the node being provisioned as a minion:

    scp tripleo-undercloud-outputs.yaml tripleo-undercloud-passwords.yaml <non-root-user>@<minion-machine>:
  3. (Optional) Copy Undercloud CA certificate if SSL is enabled.

    On the undercloud:

    scp /etc/pki/ca-trust/source/anchors/cm-local-ca.pem <non-root-user>@<minion-machine>:

    On the minion:

    sudo update-ca-trust enable
    sudo cp cm-local-ca.pem /etc/pki/ca-trust/source/anchors/undercloud-ca.pem
    sudo update-ca-trust extract
  4. Prepare the configuration file:

    cp /usr/share/python-tripleoclient/minion.conf.sample ~/minion.conf

    Update the settings in this file to match the desired configuration. The options in the minion.conf are similarly configured as the undercloud.conf on the undercloud node. It is important to configure the minion_local_ip and the minion_local_interface to match the available interfaces on the minion system.


    The minion configured interface and ip must be on the control plane network.

  5. Run the command to install the minion:

    To deploy a minion:

    openstack undercloud minion install
  6. Verify services

    • Heat Engine

      By default only the heat-engine service is configured. To verify it has been configured correctly, run the following on the undercloud:

      source ~/stackrc
      openstack orchestration service list

      Example output:

      (undercloud) [stack@undercloud ~]$ openstack orchestration service list
      | Hostname               | Binary      | Engine ID                            | Host                   | Topic  | Updated At                 | Status |
      | undercloud.localdomain | heat-engine | b1af4e18-6859-4b73-b1cf-87674bd0ce1f | undercloud.localdomain | engine | 2019-07-25T23:19:34.000000 | up     |
      | minion.localdomain     | heat-engine | 3a0d7080-06a9-4049-bb00-dbdcafbce0fc | minion.localdomain     | engine | 2019-07-25T23:19:24.000000 | up     |
      | undercloud.localdomain | heat-engine | f6ccea46-2b30-4869-b06f-935c342a9ed6 | undercloud.localdomain | engine | 2019-07-25T23:19:34.000000 | up     |
      | minion.localdomain     | heat-engine | eef759de-f7d3-472a-afbc-878eb6a3b9c0 | minion.localdomain     | engine | 2019-07-25T23:19:24.000000 | up     |
      | minion.localdomain     | heat-engine | 7f076afe-5116-45ad-9f08-aab7fbfda40b | minion.localdomain     | engine | 2019-07-25T23:19:24.000000 | up     |
      | undercloud.localdomain | heat-engine | 038ead61-91f1-4739-8537-df63a9e2c917 | undercloud.localdomain | engine | 2019-07-25T23:19:34.000000 | up     |
      | undercloud.localdomain | heat-engine | f16a4f55-b053-4650-9202-781aef55698e | undercloud.localdomain | engine | 2019-07-25T23:19:36.000000 | up     |
      | minion.localdomain     | heat-engine | e853d9c9-9f75-4958-ad9b-49e4b63b79b2 | minion.localdomain     | engine | 2019-07-25T23:19:24.000000 | up     |
    • Ironic Conductor

      If the ironic conductor service has been enabled, run the following on the undercloud:

      source ~/stackrc
      baremetal conductor list

      Example output:

      (undercloud) [stack@undercloud ~]$ baremetal conductor list
      | Hostname               | Conductor Group | Alive |
      | undercloud.localdomain |                 | True  |
      | minion.localdomain     |                 | True  |