Chapter 7. Creating the overcloud

When your custom environment files are ready, you can specify the flavors and nodes that each role uses and then execute the deployment. The following subsections explain both steps in greater detail.

7.1. Assigning nodes and flavors to roles

Planning an overcloud deployment involves specifying how many nodes and which flavors to assign to each role. Like all Heat template parameters, these role specifications are declared in the parameter_defaults section of your environment file (in this case, ~/templates/storage-config.yaml).

For this purpose, use the following parameters:

Table 7.1. Roles and Flavors for Overcloud Nodes

Heat Template ParameterDescription


The number of Controller nodes to scale out


The flavor to use for Controller nodes (control)


The number of Compute nodes to scale out


The flavor to use for Compute nodes (compute)


The number of Ceph storage (OSD) nodes to scale out


The flavor to use for Ceph Storage (OSD) nodes (ceph-storage)


The number of dedicated Ceph MON nodes to scale out


The flavor to use for dedicated Ceph MON nodes (ceph-mon)


The number of dedicated Ceph MDS nodes to scale out


The flavor to use for dedicated Ceph MDS nodes (ceph-mds)


The CephMonCount, CephMdsCount, OvercloudCephMonFlavor, and OvercloudCephMdsFlavor parameters (along with the ceph-mon and ceph-mds flavors) will only be valid if you created a custom CephMON and CephMds role, as described in Chapter 3, Deploying Ceph services on dedicated nodes.

For example, to configure the overcloud to deploy three nodes for each role (Controller, Compute, Ceph-Storage, and CephMon), add the following to your parameter_defaults:

  ControllerCount: 3
  OvercloudControlFlavor: control
  ComputeCount: 3
  OvercloudComputeFlavor: compute
  CephStorageCount: 3
  OvercloudCephStorageFlavor: ceph-storage
  CephMonCount: 3
  OvercloudCephMonFlavor: ceph-mon
  CephMdsCount: 3
  OvercloudCephMdsFlavor: ceph-mds

See Creating the Overcloud with the CLI Tools from the Director Installation and Usage guide for a more complete list of Heat template parameters.

7.2. Initiating overcloud deployment


During undercloud installation, set generate_service_certificate=false in the undercloud.conf file. Otherwise, you must inject a trust anchor when you deploy the overcloud, as described in Enabling SSL/TLS on Overcloud Public Endpoints in the Advanced Overcloud Customization guide.

If you want to add Ceph Dashboard during your overcloud deployment, see Chapter 8, Adding the Red Hat Ceph Storage Dashboard to an overcloud deployment.

The creation of the overcloud requires additional arguments for the openstack overcloud deploy command. For example:

$ openstack overcloud deploy --templates -r /home/stack/templates/roles_data_custom.yaml \
  -e /usr/share/openstack-tripleo-heat-templates/environments/ceph-ansible/ceph-ansible.yaml \
  -e /usr/share/openstack-tripleo-heat-templates/environments/ceph-ansible/ceph-rgw.yaml \
  -e /usr/share/openstack-tripleo-heat-templates/environments/ceph-ansible/ceph-mds.yaml
  -e /usr/share/openstack-tripleo-heat-templates/environments/cinder-backup.yaml \
  -e /home/stack/templates/storage-config.yaml \
  -e /home/stack/templates/ceph-config.yaml \

The above command uses the following options:

  • --templates - Creates the Overcloud from the default Heat template collection (namely, /usr/share/openstack-tripleo-heat-templates/).
  • -r /home/stack/templates/roles_data_custom.yaml - Specifies the customized roles definition file from Chapter 3, Deploying Ceph services on dedicated nodes, which adds custom roles for either Ceph MON or Ceph MDS services. These roles allow either service to be installed on dedicated nodes.
  • -e /usr/share/openstack-tripleo-heat-templates/environments/ceph-ansible/ceph-ansible.yaml - Sets the director to create a Ceph cluster. In particular, this environment file will deploy a Ceph cluster with containerized Ceph Storage nodes.
  • -e /usr/share/openstack-tripleo-heat-templates/environments/ceph-ansible/ceph-rgw.yaml - Enables the Ceph Object Gateway, as described in Section 4.2, “Enabling the Ceph Object Gateway”.
  • -e /usr/share/openstack-tripleo-heat-templates/environments/ceph-ansible/ceph-mds.yaml - Enables the Ceph Metadata Server, as described in Section 4.1, “Enabling the Ceph Metadata Server”.
  • -e /usr/share/openstack-tripleo-heat-templates/environments/cinder-backup.yaml - Enables the Block Storage Backup service (cinder-backup), as described in Section 4.4, “Configuring the Backup Service to use Ceph”.
  • -e /home/stack/templates/storage-config.yaml - Adds the environment file containing your custom Ceph Storage configuration.
  • -e /home/stack/templates/ceph-config.yaml - Adds the environment file containing your custom Ceph cluster settings, as described in Chapter 5, Customizing the Ceph Storage cluster.
  • --ntp-server - Sets our NTP server.

You can also use an answers file to invoke all your templates and environment files. For example, you can use the following command to deploy an identical overcloud:

$ openstack overcloud deploy -r /home/stack/templates/roles_data_custom.yaml \
  --answers-file /home/stack/templates/answers.yaml --ntp-server

In this case, the answers file /home/stack/templates/answers.yaml contains:

templates: /usr/share/openstack-tripleo-heat-templates/
  - /usr/share/openstack-tripleo-heat-templates/environments/ceph-ansible/ceph-ansible.yaml
  - /usr/share/openstack-tripleo-heat-templates/environments/ceph-rgw.yaml
  - /usr/share/openstack-tripleo-heat-templates/environments/ceph-mds.yaml
  - /usr/share/openstack-tripleo-heat-templates/environments/cinder-backup.yaml
  - /home/stack/templates/storage-config.yaml
  - /home/stack/templates/ceph-config.yaml

See Including environment files in an overcloud deployment for more details.

For a full list of options, enter:

$ openstack help overcloud deploy

For more information, see Configuring a basic overcloud with the CLI tools in the Director Installation and Usage guide.

The overcloud creation process begins and the director provisions your nodes. This process takes some time to complete. To view the status of the overcloud creation, open a separate terminal as the stack user and enter the following commands:

$ source ~/stackrc
$ openstack stack list --nested

7.2.1. Limiting the nodes on which ceph-ansible runs

You can reduce deployment update time by limiting the nodes where ceph-ansible runs. When Red Hat OpenStack Platform (RHOSP) uses config-download to configure Ceph, you can use the --limit option to specify a list of nodes, instead of running config-download and ceph-ansible across your entire deployment. This feature is useful, for example, as part of scaling up your overcloud, or replacing a failed disk. In these scenarios, the deployment can run only on the new nodes that you add to the environment.

Example scenario that uses --limit in a failed disk replacement

In the following example procedure, the Ceph storage node oc0-cephstorage-0 has a disk failure so it receives a new factory clean disk. Ansible needs to run on the oc0-cephstorage-0 node so that the new disk can be used as an OSD but it does not need to run on all of the other Ceph storage nodes. Replace the example environment files and node names with those appropriate to your environment.


  1. Log in to the undercloud node as the stack user and source the stackrc credentials file:

    # source stackrc
  2. Complete one of the following steps so that the new disk is used to start the missing OSD.

    • Run a stack update and include the --limit option to specify the nodes where you want ceph-ansible to run:

      $ openstack overcloud deploy --templates \
        -r /home/stack/roles_data.yaml \
        -n /usr/share/openstack-tripleo-heat-templates/network_data_dashboard.yaml \
        -e /usr/share/openstack-tripleo-heat-templates/environments/ceph-ansible/ceph-ansible.yaml \
        -e ~/my-ceph-settings.yaml \
        -e <other-environment_files> \
        --limit oc0-controller-0:oc0-controller-2:oc0-controller-1:oc0-cephstorage-0:undercloud

      In this example, the Controllers are included because the Ceph mons need Ansible to change their OSD definitions.

    • If config-download has generated an script, you can also run the script with the --limit option to pass the specified nodes to ceph-ansible:

      ./ --limit oc0-controller-0:oc0-controller-2:oc0-controller-1:oc0-cephstorage-0:undercloud
      You must always include the undercloud in the limit list otherwise ceph-ansible cannot be executed when you use --limit. This is necessary because the ceph-ansible execution occurs through the external_deploy_steps_tasks playbook, which runs only on the undercloud.