Chapter 4. Preparing overcloud templates for DCN deployment 4.1. Prerequisites for using separate heat stacks Your environment must meet the following prerequisites before you create a deployment using separate heat stacks: An installed instance of Red Hat OpenStack Platform director 17.1. For Ceph Storage users: access to Red Hat Ceph Storage 5. For the central location: three nodes that are capable of serving as central Controller nodes. All three Controller nodes must be in the same heat stack. You cannot split Controller nodes, or any of the control plane services, across separate heat stacks. Ceph storage is a requirement at the central location if you plan to deploy Ceph storage at the edge. For each additional DCN site: three HCI compute nodes. All nodes must be pre-provisioned or able to PXE boot from the central deployment network. You can use a DHCP relay to enable this connectivity for DCNs. All nodes have been introspected by ironic. Red Hat recommends leaving the <role>HostnameFormat parameter as the default value: %stackname%-<role>-%index%. If you do not include the %stackname% prefix, your overcloud uses the same hostnames for distributed compute nodes in different stacks. Ensure that your distributed compute nodes use the %stackname% prefix to distinguish nodes from different edge sites. For example, if you deploy two edge sites named dcn0 and dcn1 , the stack name prefix helps you to distinguish between dcn0-distributedcompute-0 and dcn1-distributedcompute-0 when you run the openstack server list command on the undercloud. Source the centralrc authentication file to schedule workloads at edge sites as well as at the central location. You do not require authentication files that are automatically generated for edge sites. 4.2. Limitations of the example separate heat stacks deployment This document provides an example deployment that uses separate heat stacks on Red Hat OpenStack Platform. This example environment has the following limitations: Spine/Leaf networking - The example in this guide does not demonstrate routing requirements, which are required in distributed compute node (DCN) deployments. Ironic DHCP Relay - This guide does not include how to configure Ironic with a DHCP relay. 4.3. Designing your separate heat stacks deployment To segment your deployment within separate heat stacks, you must first deploy a single overcloud with the control plane. You can then create separate stacks for the distributed compute node (DCN) sites. The following example shows separate stacks for different node types: Controller nodes: A separate heat stack named central , for example, deploys the controllers. When you create new heat stacks for the DCN sites, you must create them with data from the central stack. The Controller nodes must be available for any instance management tasks. DCN sites: You can have separate, uniquely named heat stacks, such as dcn0 , dcn1 , and so on. Use a DHCP relay to extend the provisioning network to the remote site. Note You must create a separate availability zone (AZ) for each stack. 4.4. Managing separate heat stacks The procedures in this guide show how to organize the environment files for three heat stacks: central , dcn0 , and dcn1 . Red Hat recommends that you store the templates for each heat stack in a separate directory to keep the information about each deployment isolated. Procedure Define the central heat stack: Extract data from the central heat stack into a common directory for all DCN sites: Define the dcn0 site. To deploy more DCN sites, create additional dcn directories by number. Note The touch is used to provide an example of file organization. Each file must contain the appropriate content for successful deployments. 4.5. Retrieving the container images Use the following procedure, and its example file contents, to retrieve the container images you need for deployments with separate heat stacks. You must ensure the container images for optional or edge-specific services are included by running the openstack container image prepare command with edge site's environment files. For more information, see Preparing container images in the Installing and managing Red Hat OpenStack Platform with director guide. Procedure Add your Registry Service Account credentials to containers.yaml . Generate the environment file as images-env.yaml : The resulting images-env.yaml file is included as part of the overcloud deployment procedure for the stack for which it is generated. 4.6. Creating fast datapath roles for the edge To use fast datapath services at the edge, you must create a custom role that defines both fast datapath and edge services. When you create the roles file for deployment, you can include the newly created role that defines services needed for both distributed compute node architecture and fast datapath services such as DPDK or SR-IOV. For example, create a custom role for distributedCompute with DPDK: Prerequisites A successful undercloud installation. For more information, see Installing the undercloud . Procedure Log in to the undercloud host as the stack user. Copy the default roles directory: Create a new file named DistributedComputeDpdk.yaml from the DistributedCompute.yaml file: Add DPDK services to the new DistributedComputeDpdk.yaml file. You can identify the parameters that you need to add by identifying the parameters in the ComputeOvsDpdk.yaml file that are not present in the DistributedComputeDpdk.yaml file. In the output, the parameters that are preceded by + are present in the ComputeOvsDpdk.yaml file but are not present in the DistributedComputeDpdk.yaml file. Include these parameters in the new DistributedComputeDpdk.yaml file. Use the DistributedComputeDpdk.yaml to create a DistributedComputeDpdk roles file : You can use this same method to create fast datapath roles for SR-IOV, or a combination of SR-IOV and DPDK for the edge to meet your requirements. 4.7. Configuring jumbo frames Jumbo frames are frames with an MTU of 9,000. Jumbo frames are not mandatory for the Storage and Storage Management networks but the increase in MTU size improves storage performance. If you want to use jumbo frames, you must configure all network switch ports in the data path to support jumbo frames. Important Network configuration changes such as MTU settings must be completed during the initial deployment. They cannot be applied to an existing deployment. Procedure Log in to the undercloud node as the stack user. Locate the network definition file. Modify the network definition file to extend the template to include the StorageMgmtIpSubnet and StorageMgmtNetworkVlanID attributes of the Storage Management network. Set the mtu attribute of the interfaces to 9000 . The following is an example of implementing these interface settings: Note For a complete example of a network definition file, see Example network definition file . Save the changes to the network definition file. Note All network switch ports between servers using the interface with the new MTU setting must be updated to support jumbo frames. If these switch changes are not made, problems will develop at the application layer that can cause the Red Hat Ceph Storage cluster to not reach quorum. If these settings are made and these problems are still observed, verify all hosts using the network configured for jumbo frames can communicate at the configured MTU setting. Use a command like the following example to perform this task: ping -M do -s 8972 172.16.1.11 If you are planning to deploy edge sites without block storage, see the following: Chapter 5, Installing the central location Section 6.2, "Deploying edge nodes without storage" If you plan to deploy edge sites with Red Hat Ceph Storage, see the following: Chapter 5, Installing the central location Section 7.4, "Deploying edge sites with hyperconverged storage"

Commands:
mkdir central touch central/overrides.yaml
mkdir dcn-common touch dcn-common/overrides.yaml
mkdir dcn0 touch dcn0/overrides.yaml
parameter_defaults: ContainerImagePrepare: - push_destination: true set: ceph_namespace: registry.redhat.io/rhceph ceph_image: rhceph-6-rhel9 ceph_tag: latest name_prefix: openstack- namespace: registry.redhat.io/rhosp17-rhel9 tag: latest ContainerImageRegistryCredentials: # https://access.redhat.com/RegistryAuthentication registry.redhat.io: registry-service-account-username: registry-service-account-password
sudo openstack tripleo container image prepare -e containers.yaml --output-env-file images-env.yaml
cp -r /usr/share/openstack-tripleo-heat-templates/roles ~/.
cp roles/DistributedCompute.yaml roles/DistributedComputeDpdk.yaml
diff -u roles/DistributedComputeDpdk.yaml roles/ComputeOvsDpdk.yaml
openstack overcloud roles generate --roles-path ~/roles/ -o ~/roles/roles-custom.yaml DistributedComputeDpdk
- type: interface name: em2 use_dhcp: false mtu: 9000 - type: vlan device: em2 mtu: 9000 use_dhcp: false vlan_id: {get_param: StorageMgmtNetworkVlanID} addresses: - ip_netmask: {get_param: StorageMgmtIpSubnet} - type: vlan device: em2 mtu: 9000 use_dhcp: false vlan_id: {get_param: StorageNetworkVlanID} addresses: - ip_netmask: {get_param: StorageIpSubnet}