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Virtual machines deployment

Virtual machines deployment

Two files are needed to deploy a virtual machine on SEAPATH:

  • The disk in qcow2 format, where the data of the VM is stored

  • The Libvirt XML file that defines the hardware to emulate for the VM

This section doesn’t explain how to create the qcow2 disk. More information at Software provider - How to deploy your application

Ansible VM deployment

All VMs to deploy must be configured inside the VMs Ansible group

We advise creating a separate inventory for the VMs to avoid side effects when launching playbooks

Each VM host must contain, at minimum, two variables:

  • vm_disk: The location of the qcow2 file on the administration machine

  • vm_template: The location of the Libvirt XML file on the administration machine

The vm_template variable can point either directly to a Libvirt XML file, or to a jinja2 templated Libvirt XML file. The templated file is useful to customize the VM inside the Ansible inventory instead of modifying the XML directly.

SEAPATH provides two Libvirt XML templates:

  • guest.xml.j2 for a basic configurable VM

  • one for the ABB SSC600 SW virtual machine.

The guest.xml.j2 Libvirt XML file was specifically configured to work on SEAPATH with or without real time performances. It should be able to deploy almost all Linux UEFI VMs; it is thus the recommended XML to use.

For all other usages, you will have to write your own non-templated Libvirt XML file

Use a templated Libvirt XML (guest.xml.j2)

SEAPATH provides a templated Libvirt XML file located in the Ansible repository at templates/vm/guest.xml.j2

Multiple variables are available directly in the VM inventory to customize this template and specify VM characteristics such as names, IP addresses, CPU settings, and more. The full documentation is located in the deploy_vms_standalone and deploy_vms_cluster role documentation.

For a virtual machine with determinism and performance needs, we recommend using both the "isolated" and "rt" feature. For more information, refer to Real time virtual machine configuration

Note that the guest.xml.j2 template relies only on a UEFI boot-loader for the VMs. If your VM uses legacy BIOS, you must create your own Libvirt XML file.

An example inventory is provided on the Ansible GitHub repository.

If your VM has real-time needs, refer to Real time virtual machine configuration

To connect your VM to the different SEAPATH networks, refer to Connect a virtual machine to the network

Use a non-templated Libvirt XML file

Standard Libvirt XML files can be used directly with the vm_template variables, without any additional information in the VM inventory.

To create your Libvirt XML file, refer to https://libvirt.org/formatdomain.html

When deploying a VM on the SEAPATH cluster, do not include disk management in your Libvirt XML.

The disk of the VM is automatically replicated on the Ceph storage and the XML modified to include Ceph RBD communication. More information at The vm_manager tool

If your VM has real-time needs, refer to Real time virtual machine configuration

To connect your VM to the different SEAPATH networks, refer to Connect a virtual machine to the network

Define location and co-location constraint for the VMs (cluster only)

When deploying VMs on the cluster, it is possible to select a mandatory or preferred hypervisor to run on (location rules). It is also possible to select VMs that must run on the same machine (co-location rules).

All these rules can be defined in the VM inventory using the cluster_vm module.

Pacemaker meta, params and utilization can also be defined there.

See the cluster_vm module role documentation for more information.

Deployment

To deploy your VMs on SEAPATH machines, you can call

  • playbooks/deploy_vms_cluster.yaml, for a deployment on a SEAPATH cluster

ansible-playbook -i inventories/cluster_inventory.yaml -i inventories/vm_inventory.yaml playbooks/deploy_vms_cluster.yaml

  • playbooks/deploy_vms_standalone.yaml, for deployment on a SEAPATH standalone machine

ansible-playbook -i inventories/standalone_inventory.yaml -i inventories/vm_inventory.yaml playbooks/deploy_vms_standalone.yaml

Advanced playbook with the cluster_vm Ansible module

The cluster_vm Ansible module is a wrapper above the vm_manager command line interface. It serves as an Ansible connection to deploy VMs on SEAPATH.
It is primarily used inside the deploy_vms_standalone and deploy_vms_cluster roles.

It can also be called directly from custom playbooks to perform actions on VMs. For instance, an example playbook that removes a VM on the cluster:

- name: Remove vm1 cluster_vm: name: vm1 command: remove

Playbooks can be executed on any hypervisor.

The complete documentation of cluster_vm is at https://galaxy.ansible.com/ui/repo/published/seapath/ansible/content/module/cluster_vm/

cluster_vm is a wrapper around the vm_manager command line interface. All actions of vm_manager can be done with this module.

More information at The vm_manager tool