Using Already Deployed Servers

Using Already Deployed Servers

TripleO can be used with servers that have already been deployed and provisioned with a running operating system.

In this deployment scenario, Nova and Ironic from the Undercloud are not used to do any server deployment, installation, or power management. An external to TripleO and already existing provisioning tool is expected to have already installed an operating system on the servers that are intended to be used as nodes in the Overcloud.


It’s an all or nothing approach when using already deployed servers. Mixing using deployed servers with servers provisioned with Nova and Ironic is not currently possible.

Deployed Server Requirements


Network interfaces

It’s recommended that each server have a dedicated management NIC with externally configured connectivity so that the servers are reachable outside of any networking configuration done by the OpenStack deployment.

A separate interface, or set of interfaces should then be used for the OpenStack deployment itself, configured in the typical fashion with a set of NIC config templates during the Overcloud deployment. See Configuring Network Isolation for more information on configuring networking.


Neutron in the Undercloud is not used for providing DHCP services for the Overcloud nodes, hence a dedicated provisioning network with L2 connectivity is not a requirement in this scenario. Neutron is however still used for IPAM for the purposes of assigning IP addresses to the port resources created by tripleo-heat-templates.

Network L3 connectivity is still a requirement between the Undercloud and Overcloud nodes. The Overcloud nodes will communicate over HTTP(s) to poll the Undercloud for software configuration to be applied by their local agents.

The polling process requires L3 routable network connectivity from the deployed servers to the Undercloud OpenStack API’s.

If the ctlplane is a routable network from the deployed servers, then the deployed servers can connect directly to the IP address specified by local_ip from undercloud.conf. Alternatively, they could connect to the virtual IP address (VIP) specified by undercloud_public_host, if VIP’s are in use.

In the scenario where the ctlplane is not routable from the deployed servers, then undercloud_public_host in undercloud.conf must be set to a hostname that resolves to a routable IP address for the deployed servers. SSL also must be configured on the Undercloud so that HAProxy is bound to that configured hostname. Specify either undercloud_service_certifcate or generate_service_certificate to enable SSL during the Undercloud installation. See Deploying with SSL for more information on configuring SSL.

Additionally, when the ctlplane is not routable from the deployed servers, Heat on the Undercloud must be configured to use the public endpoints for OpenStack service communication during the polling process and be configured to use Swift temp URL’s for signaling. Add the following hiera data to a new or existing hiera file:

heat_clients_endpoint_type: public
heat::engine::default_deployment_signal_transport: TEMP_URL_SIGNAL

Specify the path to the hiera file with the hieradata_override configuration in undercloud.conf:

hieradata_override = /path/to/custom/hiera/file.yaml


Configure the deployed servers that will be used as nodes in the Overcloud with L3 connectivity to the Undercloud as needed. The configuration could be done via static or DHCP IP assignment.

Further networking configuration of Overcloud nodes is the same as in a typical TripleO deployment, except for:

  • Initial configuration of L3 connectivity to the Undercloud
  • No requirement for dedicating a separate L2 network for provisioning

Testing Connectivity

On each Overcloud node run the following commands that test connectivity to the Undercloud’s IP address where OpenStack services are bound. Use either local_ip or undercloud_public_host in the following examples.

Test basic connectivity to the Undercloud:

ping <undercloud local_ip>

Test HTTP/HTTPS connectivity to Heat API on the Undercloud:

curl <undercloud local_ip>:8000

Sample output:

{"versions": [{"status": "CURRENT", "id": "v1.0", "links": [{"href": "", "rel": "self"}]}]}

Test HTTP/HTTPS connectivity to Swift on the Undercloud The html output shown here is expected! While it indicates no resource was found, it demonstrates successful connectivity to the HTTP service:

curl <undercloud local_ip>:8080

Sample output:

<html><h1>Not Found</h1><p>The resource could not be found.</p></html>

The output from the above curl commands demonstrates successful connectivity to the web services bound at the Undercloud’s local_ip IP address. It’s important to verify this connectivity prior to starting the deployment, otherwise the deployment may be unsuccessful and difficult to debug.

Package repositories

The servers will need to already have the appropriately enabled yum repositories as packages will be installed on the servers during the Overcloud deployment. The enabling of repositories on the Overcloud nodes is the same as it is for other areas of TripleO, such as Undercloud installation. See Repository Enablement for the detailed steps on how to enable the standard repositories for TripleO.

Initial Package Installation

Once the repositories have been enabled on the deployed servers, the initial packages for the Heat agent need to be installed. Run the following command on each server intending to be used as part of the Overcloud:

sudo yum -y install python-heat-agent*

Deploying the Overcloud

Deployment Command

The functionality of using already deployed servers is enabled by passing additional Heat environment files to the openstack overcloud deploy command.:

openstack overcloud deploy \
  <other cli arguments> \
  --disable-validations \
  -e /usr/share/openstack-tripleo-heat-templates/environments/deployed-server-environment.yaml \
  -e /usr/share/openstack-tripleo-heat-templates/environments/deployed-server-bootstrap-environment-centos.yaml \
  -r /usr/share/openstack-tripleo-heat-templates/deployed-server/deployed-server-roles-data.yaml

The --disable-validations option disables the basic Nova, Ironic, and Glance related validations executed by python-tripleoclient. These validations are not necessary since those services will not be used to deploy the Overcloud.

The deployed-server.yaml environment takes advantage of the template composition nature of Heat and tripleo-heat-templates to substitute OS::Heat::DeployedServer resources in place of OS::Nova::Server.

The deployed-server-bootstrap-centos.yaml environment triggers execution of a bootstrap script on the deployed servers to install further needed packages and make other configurations necessary for Overcloud deployment.

The custom roles file, deployed-server-roles-data.yaml contains the custom roles used during the deployment. Further customization of the roles data is possible when using deployed servers. When doing so, be sure to include the disable_constraints key on each defined role as seen in deployed-server-roles-data.yaml. This key disables the Heat defined constraints in the generated role templates. These constraints validate resources such as Nova flavors and Glance images, resources that are not needed when using deployed servers. An example role using disable_constraints looks like:

- name: ControllerDeployedServer
  disable_constraints: True
  CountDefault: 1
    - OS::TripleO::Services::CACerts
    - OS::TripleO::Services::CephMon
    - OS::TripleO::Services::CephExternal
    - OS::TripleO::Services::CephRgw
    ... <additional services>

Network Configuration

The default network interface configuration mappings for the deployed-server roles are:

OS::TripleO::ControllerDeployedServer::Net::SoftwareConfig: net-config-static-bridge.yaml
OS::TripleO::ComputeDeployedServer::Net::SoftwareConfig: net-config-static.yaml
OS::TripleO::BlockStorageDeployedServer::Net::SoftwareConfig: net-config-static.yaml
OS::TripleO::ObjectStorageDeployedServer::Net::SoftwareConfig: net-config-static.yaml
OS::TripleO::CephStorageDeployedServer::Net::SoftwareConfig: net-config-static.yaml

The default nic configs use static IP assignment instead of the default of DHCP. This is due to there being no requirement of L2 connectivity between the undercloud and overcloud. However, the nic config templates can be overridden to use whatever configuration is desired (including DHCP).

As is the case when not using deployed-servers, the following parameters need to also be specified:

  NeutronPublicInterface: eth1

ControlPlaneDefaultRoute and EC2MetadataIp are not necessarily meaningful parameters depending on the network architecture in use with deployed servers. However, they still must be specified as they are required parameters for the template interface.

The DeployedServerPortMap parameter can be used to assign fixed IP’s from either the ctlplane network or the IP address range for the overcloud.

If the deployed servers were preconfigured with IP addresses from the ctlplane network for the initial undercloud connectivity, then the same IP addresses can be reused during the overcloud deployment. Add the following to a new environment file and specify the environment file as part of the deployment command:

  OS::TripleO::DeployedServer::ControlPlanePort: ../deployed-server/deployed-neutron-port.yaml
        - ip_address:
        - cidr: 24
        - ip_address:
        - cidr: 24

The value of the DeployedServerPortMap variable is a map. The keys correspond to the <short hostname>-ctlplane of the deployed servers. Specify the ip addresses to be assigned under fixed_ips.

In the case where the ctlplane is not routable from the deployed servers, you can use DeployedServerPortMap to assign an IP address from any CIDR:

  OS::TripleO::DeployedServer::ControlPlanePort: /usr/share/openstack-tripleo-heat-templates/deployed-server/deployed-neutron-port.yaml
  OS::TripleO::Network::Ports::ControlPlaneVipPort: /usr/share/openstack-tripleo-heat-templates/deployed-server/deployed-neutron-port.yaml
  OS::TripleO::Network::Ports::RedisVipPort: /usr/share/openstack-tripleo-heat-templates/network/ports/noop.yaml

  NeutronPublicInterface: eth1

        - ip_address:
        - ip_address:
        - ip_address:

In the above example, notice how RedisVipPort is mapped to network/ports/noop.yaml. This mapping is due to the fact that the Redis VIP IP address comes from the ctlplane by default. The EC2MetadataIp and ControlPlaneDefaultRoute parameters are set to the value of the control virtual IP address. These parameters are required to be set by the sample NIC configs, and must be set to a pingable IP address in order to pass the validations performed during deployment. Alternatively, the NIC configs could be further customized to not require these parameters.

When using network isolation, refer to the documentation on using fixed IP addresses for further information at Predictable IPs.

Configuring Deployed Servers to poll Heat

Upon executing the deployment command, Heat will begin creating the overcloud stack. The stack events are shown in the terminal as the stack operation is in progress.

The resources corresponding to the deployed server will enter CREATE_IN_PROGRESS. At this point, the Heat stack will not continue as it is waiting for signals from the servers. The agents on the deployed servers need to be configured to poll Heat for their configuration.

This point in the Heat events output will look similar to:

2017-01-14 13:25:13Z [overcloud.Compute.0.NovaCompute]: CREATE_IN_PROGRESS  state changed
2017-01-14 13:25:14Z [overcloud.Controller.0.Controller]: CREATE_IN_PROGRESS  state changed
2017-01-14 13:25:14Z [overcloud.Controller.1.Controller]: CREATE_IN_PROGRESS  state changed
2017-01-14 13:25:15Z [overcloud.Controller.2.Controller]: CREATE_IN_PROGRESS  state changed

The example output above is from a deployment with 3 controllers and 1 compute. As seen, these resources have entered the CREATE_IN_PROGRESS state.

To configure the agents on the deployed servers, the request metadata url needs to be read from Heat resource metadata on the individual resources, and configured in the /etc/os-collect-config.conf configuration file on the corresponding deployed servers.

Manual configuration of Heat agents

These steps can be used to manually configure the Heat agents (os-collect-config) on the deployed servers.

Query Heat for the request metadata url by first listing the nested deployed-server resources:

openstack stack resource list -n 5 overcloud | grep deployed-server

Example output:

| deployed-server | 895c08b8-f6f4-4564-b344-586603e7e970 | OS::Heat::DeployedServer | CREATE_COMPLETE    | 2017-01-14T13:25:12Z | overcloud-Controller-pgeu4nxsuq6r-1-v4slfaduprak-Controller-ltxdxz2fin3d |
| deployed-server | 87cd8d81-8bbe-4c0b-9bd9-f5bcd1343265 | OS::Heat::DeployedServer | CREATE_COMPLETE    | 2017-01-14T13:25:15Z | overcloud-Controller-pgeu4nxsuq6r-0-5uin56wp3ign-Controller-5wkislg4kiv5 |
| deployed-server | 3d387f61-dc6d-41f7-b3b8-5c9a0ab0ed7b | OS::Heat::DeployedServer | CREATE_COMPLETE    | 2017-01-14T13:25:16Z | overcloud-Controller-pgeu4nxsuq6r-2-m6tgzatgnqrb-Controller-yczqaulovrla |
| deployed-server | cc230478-287e-4591-a905-bbfca6c89742 | OS::Heat::DeployedServer | CREATE_COMPLETE    | 2017-01-14T13:25:13Z | overcloud-Compute-vllmnqf5d77h-0-kfm2xsdmtmr6-NovaCompute-67djxtyrwi6z |

Show the resource metadata for one of the resources. The last column in the above output is a nested stack name and is used in the command below. The command shows the resource metadata for the first controller (Controller.0):

openstack stack resource metadata overcloud-Controller-pgeu4nxsuq6r-0-5uin56wp3ign-Controller-5wkislg4kiv5 deployed-server

The above command outputs a significant amount of JSON output representing the resource metadata. To see just the request metadata_url, the command can be piped to jq to show just the needed url:

openstack stack resource metadata overcloud-Controller-pgeu4nxsuq6r-0-5uin56wp3ign-Controller-5wkislg4kiv5 deployed-server | jq -r '.["os-collect-config"].request.metadata_url'

Example output:

Using the above url, configure /etc/os-collect-config.conf on the deployed server that is intended to be used as Controller 0. The full configuration would be:



Once the configuration has been updated on the deployed server for Controller 0, restart the os-collect-config service:

sudo systemctl restart os-collect-config

Repeat the configuration for the other nodes in the Overcloud, by querying Heat for the request metadata url, and updating the os-collect-config configuration on the respective deployed servers.

Once all the agents have been properly configured, they will begin polling for the software deployments to apply locally from Heat, and the Heat stack will continue creating. If the deployment is successful, the Heat stack will eventually go to the CREATE_COMPLETE state.

Automatic configuration of Heat agents

A script is included with tripleo-heat-templates that can be used to do automatic configuration of the Heat agent on the deployed servers instead of relying on the above manual process.

The script requires that the environment variables needed to authenticate with the Undercloud’s keystone have been set in the current shell. These environment variables can be set by sourcing the Undercloud’s stackrc file.

The script also requires that the user executing the script can ssh as the same user to each deployed server, and that the remote user account has password-less sudo access.

The following shows an example of running the script:

export OVERCLOUD_ROLES="ControllerDeployedServer ComputeDeployedServer"
export ControllerDeployedServer_hosts=""
export ComputeDeployedServer_hosts=""

As shown above, the script is further configured by the $OVERCLOUD_ROLES environment variable, and corresponding $<role-name>_hosts variables.

$OVERCLOUD_ROLES is a space separated list of the role names used for the Overcloud deployment. These role names correspond to the name of the roles from the roles data file used during the deployment.

Each $<role-name>_hosts variable is a space separated list of IP addresses that are the IP addresses of the deployed servers for the roles. For example, in the above command, is the IP of Controller 0, is the IP of Controller 1, etc.

The script will take care of querying Heat for each request metadata url, configure the url in the agent configuration file on each deployed server, and restart the agent service.

Once the script executes successfully, the deployed servers will start polling Heat for software deployments and the stack will continue creating.

Scaling the Overcloud

Scaling Up

When scaling up the Overcloud, the heat agents on the new servers being added to the deployment need to be configured to correspond to the new nodes being added.

For example, when scaling out compute nodes, the steps to be completed by the user are as follows:

  1. Prepare the new deployed server(s) as shown in Deployed Server Requirements.
  2. Start the scale out command. See Scaling overcloud roles for reference.
  3. Once Heat has created the new resources for the new deployed server(s), query Heat for the request metadata url for the new nodes, and configure the remote agents as shown in Manual configuration of Heat agents.

Scaling Down

When scaling down the Overcloud, follow the scale down instructions as normal as shown in Deleting Overcloud Nodes.

The physical deployed servers that have been removed from the deployment need to be powered off. In a deployment not using deployed servers, this would typically be done with Ironic. When using deployed servers, it must be done manually, or by whatever existing power management solution is already in place. If the nodes are not powered down, they will continue to be operational and could be part of the deployment, since there are no steps to unconfigure, uninstall software, or stop services on nodes when scaling down.

Once the nodes are powered down and all needed data has been saved from the nodes, it is recommended that they be reprovisioned back to a base operating system configuration so that they do not unintentionally join the deployment in the future if they are powered back on.


Do not attempt to reuse nodes that were previously removed from the deployment without first reprovisioning them using whatever provisioning tool is in place.

Deleting the Overcloud

When deleting the Overcloud, the Overcloud nodes need to be manually powered off, otherwise, the cloud will still be active and accepting any user requests.

After archiving any data that needs to be saved from the deployment, it is recommended to reprovision the nodes to a clean base operating system. The reprovision will ensure that they do not start serving user requests, or interfere with future deployments in the case where they are powered back on in the future.

As with scaling down, do not attempt to reuse nodes from a previous deployment as part of a new deployment.

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