VM Templates

Overview

VM Templates let you save a complete instance configuration — disk, flavor, network, security groups, and key pair — as a reusable template. Deploy templates to create standardized instances with consistent configurations across your projects. Templates appear in the dedicated Compute > VM Templates page, separate from regular images and snapshots.

Prerequisites

An active instance to create a template from
Sufficient image storage quota

What a VM Template Is

A VM Template is a first-class template object surfaced in the Dashboard, implemented on top of the Image Service with a polystack_template=true discriminator and captured config metadata. It is more than a snapshot used as a base image — it also carries the surrounding launch context.

Capability	VM Template	Snapshot used as base image
Version field (e.g. `1.0`)	Yes	—
Category field (Base OS, Web Server, Database, Application, Custom)	Yes	—
Captured flavor (vCPU / RAM summary shown on the row)	Yes	—
Captured network, security groups, key pair	Yes	—
Deploy action that pre-fills the launch wizard from the captured config	Yes	—
Lives on its own Compute → VM Templates page	Yes	—
Just disk content for a future boot	—	Yes

A snapshot used as a base image gives you the disk only — the next launch needs flavor, network, security groups, and key pair to be re-chosen by hand. A VM Template captures the disk and the surrounding configuration, and its Deploy action re-applies all of it in one click.

Implementation note — under the hood, a VM Template is stored in the Image Service like any other image, marked with polystack_template=true plus the captured config metadata. Operators can list templates from the CLI with openstack image list --property polystack_template=true. The same storage backend, RBAC privileges, and quotas that apply to images apply to templates — there is no separate subsystem to learn.

View Templates

Dashboard
CLI

Navigate to Compute > VM Templates in the sidebar. The list shows all templates in your project.

Column	Description
Template Name	Template identifier (clickable to view details)
Description	Optional template description
Version	Template version (e.g., `1.0`)
Category	Base OS, Web Server, Database, Application, or Custom
Flavor	Captured flavor name
Configuration	vCPUs / RAM summary
Status	Active, Saving, etc.
Size	Template image size
Created At	Creation timestamp

Filter by Name or Status.

Administrators see an additional Project ID/Name column and can view templates across all projects.

Source credentials

source openrc.sh

List all VM templates

openstack image list --property polystack_template=true

Show template details

openstack image show <TEMPLATE_ID>

Create a Template

There are two ways to create a template:

From the VM Templates Page

Dashboard
CLI

Open the Create Template dialog

Navigate to Compute > VM Templates and click Create Template.

Select the source instance

Field	Type	Required	Description
Source Instance	Dropdown	Yes	Select an instance (`Active`, `Stopped`, `Shutoff`, or `Paused`)
Template Name	Text	Yes	Name for the template
Version	Text	Yes	Version string (default: `1.0`)
Category	Dropdown	No	Classification (default: `Custom`)
Description	Text area	No	Optional notes
Delete Instance After Conversion	Checkbox	No	Delete the source instance after template creation

Category options:

Category	Use Case
Base OS	Clean OS installations (Ubuntu, CentOS, Windows)
Web Server	Pre-configured web stacks (Nginx, Apache, etc.)
Database	Database servers (MySQL, PostgreSQL, MongoDB)
Application	Custom application stacks
Custom	General-purpose templates (default)

If Delete Instance After Conversion is checked, the source instance is permanently deleted after the template is created. This cannot be undone.

Create the template

Click Confirm. The template appears in the list with status Saving, transitioning to Active when the snapshot completes.

The template captures the full configuration: flavor, network, security groups, key pair, and availability zone. When deploying from this template, these settings are used as defaults.

Template status is Active — ready for deployment.

Source credentials

source openrc.sh

Template creation uses the platform Nova API extension:

Create a template from an instance

curl -X POST -H "X-Auth-Token: $TOKEN" \
  -H "Content-Type: application/json" \
  -d '{
    "polystack-convert-template": {
      "name": "ubuntu-web-template",
      "version": "1.0",
      "category": "web-server",
      "description": "Ubuntu 24.04 with Nginx pre-configured",
      "delete_instance": false
    }
  }' \
  "$NOVA_ENDPOINT/v2.1/servers/<INSTANCE_ID>/action"

From an Instance (Convert to Template)

Navigate to Compute > Instances. Click the More dropdown on the instance row and select Convert to Template under the Clone & Template group. The form is the same as above except the source instance is pre-selected.

Convert to Template is available for instances in Active, Stopped, Shutoff, or Paused status.

Template Detail

Dashboard
CLI

Click a template name to open the detail page. Three info cards are displayed:Template Info:

Field	Description
Template Name	Display name
Version	Version string
Category	Classification (Base OS, Web Server, etc.)
Description	Template description
Source Instance	Instance this template was created from (copyable)
Created By	User who created the template
Template Created	Creation timestamp

VM Configuration (captured from the source instance):

Field	Description
Flavor	Original flavor name
vCPUs	CPU count
RAM (MB)	Memory allocation
Disk (GB)	Root disk size
Network	Network name
Security Groups	Comma-separated list
Key Pair	SSH key pair name
Availability Zone	Zone placement

Image Info (underlying Glance image):

Field	Description
Image ID	UUID (copyable)
Status	Active, Saving, etc.
Size	Image file size
Disk Format	QCOW2, RAW, etc.
Visibility	Public, Private, or Shared
Protected	Yes/No
Checksum	Image checksum (copyable)

Show template metadata

openstack image show <TEMPLATE_ID> -f json | python3 -c "
import sys, json
img = json.load(sys.stdin)
for k, v in sorted(img.items()):
    if k.startswith('polystack_template_'):
        print(f'{k}: {v}')
"

Deploy a Template

Dashboard
CLI

Select Deploy

Navigate to Compute > VM Templates. Click the More dropdown on the template row and select Deploy.

Name the new instance

Enter a Name for the new instance. Click Confirm.The wizard redirects to the Instance Create page with the template pre-selected as the boot source image.

New instance created from the template with the captured configuration.

Launch instance from template

openstack server create \
  --image <TEMPLATE_ID> \
  --flavor <FLAVOR> \
  --network <NETWORK> \
  --key-name <KEYPAIR> \
  my-deployed-instance

Use the flavor, network, and key pair captured in the template metadata for consistent deployments:

Get template's captured config

openstack image show <TEMPLATE_ID> -c properties -f json | python3 -c "
import sys, json
props = json.load(sys.stdin)['properties']
print(f'Flavor: {props.get(\"polystack_template_flavor_name\", \"N/A\")}')
print(f'Network: {props.get(\"polystack_template_network_name\", \"N/A\")}')
print(f'Keypair: {props.get(\"polystack_template_keypair\", \"N/A\")}')
"

Edit a Template

Dashboard
CLI

Click Edit (the first row action) on the template row. You can modify:

Field	Description
Name	Template display name
Version	Version string
Category	Template classification
Description	Template description (max 255 chars)
Public	Make visible to all projects (admin only)
Protected	Prevent accidental deletion
Configuration fields	Flavor, vCPUs, RAM, Disk, Network, Key Pair, AZ

Click Confirm to save changes.

Update template metadata

openstack image set \
  --property polystack_template_version="2.0" \
  --property polystack_template_category="web-server" \
  <TEMPLATE_ID>

Delete a Template

Click the More dropdown on the template row and select Delete Template. Templates with Protected enabled must have protection removed before deletion. Batch delete is available via checkboxes.

Deleting a template permanently removes the underlying image. Instances previously deployed from this template are not affected, but no new deployments can be made.

Manage Access (Admin Only)

Administrators can share templates with specific projects via the Manage Access action in the More dropdown. This requires the template to have Shared visibility.

Template Actions Summary

Action	Location	Description
Edit	First row action	Edit template name, version, category, configuration
Deploy	More dropdown	Launch a new instance from the template
Delete	More dropdown / batch	Delete the template
Manage Access	More dropdown (admin)	Share with specific projects (requires Shared visibility)
Create Template	Primary action (top)	Create a new template from an existing instance

Next Steps

Clone an Instance

Create an exact copy of a running instance without templates

Instance Snapshots

Create point-in-time snapshots (simpler than templates)

Create an Instance

Launch instances from the 4-step wizard

Image Management

Upload and manage OS images

Core Services

Other Services

Overview

What a VM Template Is

View Templates

Create a Template

From the VM Templates Page

Open the Create Template dialog

Select the source instance

Create the template

From an Instance (Convert to Template)

Template Detail

Deploy a Template

Select Deploy

Name the new instance

Edit a Template

Delete a Template

Manage Access (Admin Only)

Template Actions Summary

Next Steps

Clone an Instance

Instance Snapshots

Create an Instance

Image Management

​Overview

​What a VM Template Is

​View Templates

​Create a Template

​From the VM Templates Page

Open the Create Template dialog

Select the source instance

Create the template

​From an Instance (Convert to Template)

​Template Detail

​Deploy a Template

Select Deploy

Name the new instance

​Edit a Template

​Delete a Template

​Manage Access (Admin Only)

​Template Actions Summary

​Next Steps

Clone an Instance

Instance Snapshots

Create an Instance

Image Management

Overview

What a VM Template Is

View Templates

Create a Template

From the VM Templates Page

From an Instance (Convert to Template)

Template Detail

Deploy a Template

Edit a Template

Delete a Template

Manage Access (Admin Only)

Template Actions Summary

Next Steps