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Chapter 8. Performing Tasks after Overcloud Creation

This chapter explores some of the functions you perform after creating your overcloud of choice.

8.1. Creating the Overcloud Tenant Network

The overcloud requires a Tenant network for instances. Source the overcloud and create an initial Tenant network in Neutron. For example:

$ source ~/overcloudrc
$ openstack network create default
$ openstack subnet create default --network default --gateway --subnet-range

This creates a basic Neutron network called default. The overcloud automatically assigns IP addresses from this network using an internal DHCP mechanism.

Confirm the created network:

$ openstack network list
| id                    | name        | subnets                              |
| 95fadaa1-5dda-4777... | default     | 7e060813-35c5-462c-a56a-1c6f8f4f332f |

8.2. Creating the Overcloud External Network

You need to create the External network on the overcloud so that you can assign floating IP addresses to instances.

Using a Native VLAN

This procedure assumes a dedicated interface or native VLAN for the External network.

Source the overcloud and create an External network in Neutron. For example:

$ source ~/overcloudrc
$ openstack network create public --external --provider-network-type flat --provider-physical-network datacentre
$ openstack subnet create public --network public --dhcp --allocation-pool start=,end= --gateway --subnet-range

In this example, you create a network with the name public. The overcloud requires this specific name for the default floating IP pool. This is also important for the validation tests in Section 8.5, “Validating the Overcloud”.

This command also maps the network to the datacentre physical network. As a default, datacentre maps to the br-ex bridge. Leave this option as the default unless you have used custom neutron settings during the overcloud creation.

Using a Non-Native VLAN

If not using the native VLAN, assign the network to a VLAN using the following commands:

$ source ~/overcloudrc
$ openstack network create public --external --provider-network-type vlan --provider-physical-network datacentre --provider-segment 104
$ openstack subnet create public --network public --dhcp --allocation-pool start=,end= --gateway --subnet-range

The provider:segmentation_id value defines the VLAN to use. In this case, you can use 104.

Confirm the created network:

$ openstack network list
| id                    | name        | subnets                              |
| d474fe1f-222d-4e32... | public      | 01c5f621-1e0f-4b9d-9c30-7dc59592a52f |

8.3. Creating Additional Floating IP Networks

Floating IP networks can use any bridge, not just br-ex, as long as you meet the following conditions:

  • NeutronExternalNetworkBridge is set to "''" in your network environment file.
  • You have mapped the additional bridge during deployment. For example, to map a new bridge called br-floating to the floating physical network:

    $ source ~/stackrc
    $ openstack overcloud deploy --templates -e /usr/share/openstack-tripleo-heat-templates/environments/network-isolation.yaml -e ~/templates/network-environment.yaml --neutron-bridge-mappings datacentre:br-ex,floating:br-floating

Create the Floating IP network after creating the overcloud:

$ source ~/overcloudrc
$ openstack network create ext-net --external --provider-physical-network floating --provider-network-type vlan --provider-segment 105
$ openstack subnet create ext-subnet --network ext-net --dhcp --allocation-pool start=,end= --gateway --subnet-range

8.4. Creating the Overcloud Provider Network

A provider network is a network attached physically to a network existing outside of the deployed overcloud. This can be an existing infrastructure network or a network that provides external access directly to instances through routing instead of floating IPs.

When creating a provider network, you associate it with a physical network, which uses a bridge mapping. This is similar to floating IP network creation. You add the provider network to both the Controller and the Compute nodes because the Compute nodes attach VM virtual network interfaces directly to the attached network interface.

For example, if the desired provider network is a VLAN on the br-ex bridge, use the following command to add a provider network on VLAN 201:

$ source ~/overcloudrc
$ openstack network create provider_network --provider-physical-network datacentre --provider-network-type vlan --provider-segment 201 --share

This command creates a shared network. It is also possible to specify a tenant instead of specifying --share. That network will only be available to the specified tenant. If you mark a provider network as external, only the operator may create ports on that network.

Add a subnet to a provider network if you want neutron to provide DHCP services to the tenant instances:

$ source ~/overcloudrc
$ openstack subnet create provider-subnet --network  provider_network --dhcp --allocation-pool start=,end= --gateway --subnet-range

Other networks might require access externally through the provider network. In this situation, create a new router so that other networks can route traffic through the provider network:

$ openstack router create external
$ openstack router set --external-gateway provider_network external

Attach other networks to this router. For example, if you had a subnet called subnet1, you can attach it to the router with the following commands:

$ openstack router add subnet external subnet1

This adds subnet1 to the routing table and allows traffic using subnet1 to route to the provider network.

8.5. Validating the Overcloud

The overcloud uses the OpenStack Integration Test Suite (tempest) tool set to conduct a series of integration tests. This section provides information on preparations for running the integration tests. For full instruction on using the OpenStack Integration Test Suite, see the OpenStack Integration Test Suite Guide.

Before Running the Integration Test Suite

If running this test from the undercloud, ensure that the undercloud host has access to the overcloud’s Internal API network. For example, add a temporary VLAN on the undercloud host to access the Internal API network (ID: 201) using the address:

$ source ~/stackrc
$ sudo ovs-vsctl add-port br-ctlplane vlan201 tag=201 -- set interface vlan201 type=internal
$ sudo ip l set dev vlan201 up; sudo ip addr add dev vlan201

Before running the OpenStack Integration Test Suite, check that the heat_stack_owner role exists in your overcloud:

$ source ~/overcloudrc
$ openstack role list
| ID                               | Name             |
| 6226a517204846d1a26d15aae1af208f | swiftoperator    |
| 7c7eb03955e545dd86bbfeb73692738b | heat_stack_owner |

If the role does not exist, create it:

$ openstack role create heat_stack_owner

After Running the Integration Test Suite

After completing the validation, remove any temporary connections to the overcloud’s Internal API. In this example, use the following commands to remove the previously created VLAN on the undercloud:

$ source ~/stackrc
$ sudo ovs-vsctl del-port vlan201

8.6. Modifying the Overcloud Environment

Sometimes you might intend to modify the overcloud to add additional features, or change the way it operates. To modify the overcloud, make modifications to your custom environment files and Heat templates, then rerun the openstack overcloud deploy command from your initial overcloud creation. For example, if you created an overcloud using Section 5.6, “Creating the Overcloud with the CLI Tools”, you would rerun the following command:

$ source ~/stackrc
$ openstack overcloud deploy --templates \
  -e ~/templates/node-info.yaml \
  -e /usr/share/openstack-tripleo-heat-templates/environments/network-isolation.yaml \
  -e ~/templates/network-environment.yaml \
  -e ~/templates/storage-environment.yaml \

The director checks the overcloud stack in heat, and then updates each item in the stack with the environment files and heat templates. It does not recreate the overcloud, but rather changes the existing overcloud.

If you aim to include a new environment file, add it to the openstack overcloud deploy command with a -e option. For example:

$ source ~/stackrc
$ openstack overcloud deploy --templates \
  -e ~/templates/new-environment.yaml \
  -e /usr/share/openstack-tripleo-heat-templates/environments/network-isolation.yaml \
  -e ~/templates/network-environment.yaml \
  -e ~/templates/storage-environment.yaml \
  -e ~/templates/node-info.yaml \

This includes the new parameters and resources from the environment file into the stack.


It is advisable not to make manual modifications to the overcloud’s configuration as the director might overwrite these modifications later.

8.7. Importing Virtual Machines into the Overcloud

Use the following procedure if you have an existing OpenStack environment and aim to migrate its virtual machines to your Red Hat OpenStack Platform environment.

Create a new image by taking a snapshot of a running server and download the image.

$ openstack server image create instance_name --name image_name
$ openstack image save image_name --file exported_vm.qcow2

Upload the exported image into the overcloud and launch a new instance.

$ openstack image create imported_image --file exported_vm.qcow2 --disk-format qcow2 --container-format bare
$ openstack server create  imported_instance --key-name default --flavor m1.demo --image imported_image --nic net-id=net_id

Each VM disk has to be copied from the existing OpenStack environment and into the new Red Hat OpenStack Platform. Snapshots using QCOW will lose their original layering system.

8.8. Migrating VMs from an Overcloud Compute Node

In some situations, you might perform maintenance on an overcloud Compute node. To prevent downtime, migrate the VMs on the Compute node to another Compute node in the overcloud.

The director configures all Compute nodes to provide secure migration. All Compute nodes also require a shared SSH key to provide each host’s nova user with access to other Compute nodes during the migration process. The director creates this key using the OS::TripleO::Services::NovaCompute composable service. This composable service is one of the main services included on all Compute roles by default (see "Composable Services and Custom Roles" in Advanced Overcloud Customization).

To migrate an instance:

  1. From the undercloud, select a Compute Node to reboot and disable it:

    $ source ~/overcloudrc
    $ openstack compute service list
    $ openstack compute service set [hostname] nova-compute --disable
  2. List all instances on the Compute node:

    $ openstack server list --host [hostname] --all-projects
  3. Migrate each instance from the disabled host. Use one of the following commands:

    1. Migrate the instance to a specific host of your choice:

      $ openstack server migrate [instance-id] --live [target-host]--wait
    2. Let nova-scheduler automatically select the target host:

      $ nova live-migration [instance-id]

      The nova command might cause some deprecation warnings, which are safe to ignore.

  4. Wait until migration completes.
  5. Confirm the instance has migrated from the Compute node:

    $ openstack server list --host [hostname] --all-projects
  6. Repeat this step until you have migrated all instances from the Compute Node.

This migrates all instances from a Compute node. You can now perform maintenance on the node without any instance downtime. To return the Compute node to an enabled state, run the following command:

$ source ~/overcloudrc
$ openstack compute service set [hostname] nova-compute --enable

8.9. Running Ansible Automation

The director provides the ability to run Ansible-based automation on your OpenStack Platform environment. The director uses the tripleo-ansible-inventory command to generate a dynamic inventory of nodes in your environment.


The dynamic inventory tool only includes the undercloud and the default controller and compute overcloud nodes. Other roles are not supported.

To view a dynamic inventory of nodes, run the tripleo-ansible-inventory command after sourcing stackrc:

$ souce ~/stackrc
$ tripleo-ansible-inventory --list

The --list option provides details on all hosts.

This outputs the dynamic inventory in a JSON format:

{"overcloud": {"children": ["controller", "compute"], "vars": {"ansible_ssh_user": "heat-admin"}}, "controller": [""], "undercloud": {"hosts": ["localhost"], "vars": {"overcloud_horizon_url": "", "overcloud_admin_password": "abcdefghijklm12345678", "ansible_connection": "local"}}, "compute": [""]}

To execute Ansible playbooks on your environment, run the ansible command and include the full path of the dynamic inventory tool using the -i option. For example:

ansible [HOSTS] -i /bin/tripleo-ansible-inventory [OTHER OPTIONS]
  • Exchange [HOSTS] for the type of hosts to use. For example:

    • controller for all Controller nodes
    • compute for all Compute nodes
    • overcloud for all overcloud child nodes i.e. controller and compute
    • undercloud for the undercloud
    • "*" for all nodes
  • Exchange [OTHER OPTIONS] for the additional Ansible options. Some useful options include:

    • --ssh-extra-args='-o StrictHostKeyChecking=no' to bypasses confirmation on host key checking.
    • -u [USER] to change the SSH user that executes the Ansible automation. The default SSH user for the overcloud is automatically defined using the ansible_ssh_user parameter in the dynamic inventory. The -u option overrides this parameter.
    • -m [MODULE] to use a specific Ansible module. The default is command, which executes Linux commands.
    • -a [MODULE_ARGS] to define arguments for the chosen module.

Ansible automation on the overcloud falls outside the standard overcloud stack. This means subsequent execution of the openstack overcloud deploy command might override Ansible-based configuration for OpenStack Platform services on overcloud nodes.

8.10. Protecting the Overcloud from Removal

To avoid accidental removal of the overcloud with the heat stack-delete overcloud command, Heat contains a set of policies to restrict certain actions. Edit the /etc/heat/policy.json and find the following parameter:

"stacks:delete": "rule:deny_stack_user"

Change it to:

"stacks:delete": "rule:deny_everybody"

Save the file.

This prevents removal of the overcloud with the heat client. To allow removal of the overcloud, revert the policy to the original value.

8.11. Removing the Overcloud

The whole overcloud can be removed when desired.

Delete any existing overcloud:

$ source ~/stackrc
$ openstack overcloud delete overcloud

Confirm the deletion of the overcloud:

$ openstack stack list

Deletion takes a few minutes.

Once the removal completes, follow the standard steps in the deployment scenarios to recreate your overcloud.

8.12. Review the Token Flush Interval

The Identity Service (keystone) uses a token-based system for access control against the other OpenStack services. After a certain period, the database will accumulate a large number of unused tokens; a default cron job flushes the token table every day. It is recommended that you monitor your environment and adjust the token flush interval as needed.

For the overcloud, you can adjust the interval using the KeystoneCronToken values. For more information, see the Overcloud Parameters guide.