Metadata Definitions

Overview

Metadata namespaces define structured, validated property schemas for images. When a namespace is defined, the Dashboard displays a guided property editor instead of a raw key-value form — ensuring consistent metadata across your image catalog. Namespaces can be public (visible to all projects) or private (visible only to the creating project).

Administrator Access Required — This operation requires the admin role. Contact your Polystack administrator if you do not have sufficient permissions.

Concepts

Concept	Description
Namespace	A named collection of property definitions for a resource type
Property	A typed key-value field with validation rules (enum, string, boolean, integer)
Object	A named group of properties within a namespace
Tag	A simple string label associated with images — for filtering and grouping
Resource type	The Polystack resource the namespace applies to — `OS::Image::Image` for images

Image Tags

Tags are the simplest form of image metadata — plain strings with no key, attached directly to an image. Use them for fast catalog filtering, grouping by OS family, compliance designation, or release milestone.

Dashboard
CLI

Navigate to Compute > Images and click Edit (the first row action) on the image.In the Tags field, type a tag and press Enter to add it. Add as many as needed, then click Confirm.

Add tags to an image

openstack image set \
  --tag ubuntu \
  --tag lts \
  --tag production-ready \
  ubuntu-24.04-lts

Filter images by tag

openstack image list --tag lts

Filter by multiple tags (AND logic)

openstack image list --tag lts --tag production-ready

Remove a specific tag

openstack image unset --tag production-ready ubuntu-24.04-lts

Recommended Tag Taxonomy

Use a consistent tagging convention across your image catalog:

Category	Example Tags
OS family	`ubuntu`, `rhel`, `debian`, `windows`, `centos`
Support tier	`lts`, `standard`, `eol`, `preview`
Status	`production-ready`, `deprecated`, `testing`, `golden`
Compliance	`pci-dss`, `hipaa`, `iso27001`, `fips`
Architecture	`x86_64`, `aarch64`
Special config	`no-cloud-init`, `virtio`, `uefi`, `gpu-compatible`

Create a Metadata Namespace

Define the namespace schema

Create a JSON file defining the namespace properties:

namespace-schema.json

{
  "namespace": "org.polystack.images",
  "display_name": "Polystack Image Properties",
  "description": "Standardized OS and hardware metadata for Polystack images",
  "visibility": "public",
  "protected": true,
  "resource_type_associations": [
    {
      "name": "OS::Image::Image",
      "prefix": ""
    }
  ],
  "properties": {
    "os_lifecycle": {
      "title": "OS Lifecycle",
      "description": "Support lifecycle status of the OS",
      "type": "string",
      "enum": ["lts", "standard", "eol"],
      "operators": ["<or>"]
    },
    "polystack_base_image": {
      "title": "Polystack Base Image",
      "description": "Whether this is an Polystack-maintained base image",
      "type": "boolean"
    },
    "os_security_patch_date": {
      "title": "Last Security Patch Date",
      "description": "Date of the most recent OS security patch applied",
      "type": "string",
      "pattern": "^[0-9]{4}-[0-9]{2}-[0-9]{2}$"
    }
  }
}

Register the namespace

Create metadata namespace

openstack metric namespace create \
  --schema namespace-schema.json \
  --resource-type OS::Image::Image \
  org.polystack.images

Verify namespace is active

List registered namespaces

openstack metric namespace list

The org.polystack.images namespace appears in the list.

Use Namespace Properties

Once a namespace is registered, its properties appear in the Dashboard image editor as a structured form. Set them via CLI:

Set namespace-defined properties on an image

openstack image set \
  --property os_lifecycle=lts \
  --property polystack_base_image=true \
  --property os_security_patch_date=2026-03-15 \
  ubuntu-24.04-lts

Manage Namespaces

openstack metric namespace list

openstack metric namespace show org.polystack.images

openstack metric namespace delete org.polystack.images

Deleting a namespace removes the property schema definitions but does not remove existing property values from images. Images retain their property values even after the namespace is deleted.

Property Type Reference

Type	Description	Example
`string`	Free-text string (with optional `enum` or `pattern`)	`"lts"`, `"standard"`
`boolean`	True/false value	`true`, `false`
`integer`	Whole number	`4`, `8096`
`number`	Floating-point number	`3.14`
`array`	List of values	`["tag1", "tag2"]`

Next Steps

Image Properties

Set properties on individual images using the defined namespace schemas.

Security

Protect critical metadata properties from unauthorized modification.

Storage Backends

Configure the backend that stores the image data alongside its metadata.

Admin Troubleshooting

Resolve metadata namespace and property validation issues.

Core Services

Other Services

Overview

Concepts

Image Tags

Recommended Tag Taxonomy

Create a Metadata Namespace

Define the namespace schema

Register the namespace

Verify namespace is active

Use Namespace Properties

Manage Namespaces

Property Type Reference

Next Steps

Image Properties

Security

Storage Backends

Admin Troubleshooting

​Overview

​Concepts

​Image Tags

​Recommended Tag Taxonomy

​Create a Metadata Namespace

Define the namespace schema

Register the namespace

Verify namespace is active

​Use Namespace Properties

​Manage Namespaces

​Property Type Reference

​Next Steps

Image Properties

Security

Storage Backends

Admin Troubleshooting

Overview

Concepts

Image Tags

Recommended Tag Taxonomy

Create a Metadata Namespace

Use Namespace Properties

Manage Namespaces

Property Type Reference

Next Steps