feat(cinder): add VAST data volume backend support

[Donny Arief Oktavian (donnyao)]

Summary

Adds support for the VAST Data volume backend in Cinder, introduced in OpenStack 2026.1.

Changes

plugins/filter/storage.py

• New VolumeBackendVast class with:
  • Required: address, subsystem, vippool_name
  • Auth: api_token or username + password (validated at model level)
  • Optional: tenant_name
  • Uses cinder.volume.drivers.vastdata.driver.VASTVolumeDriver
  • Inherits _HostAttachedVolumeBackend (iSCSI enablement, trimmed dependency graph)
• Registered in the VolumeBackend discriminated union

tests/unit/plugins/filter/test_storage.py

• Tests for API token auth, username/password auth, optional tenant name, and missing credentials validation

doc/source/deploy/storage.rst

• New VAST data section documenting all configuration fields

Example configuration

atmosphere_storage:
  volumes:
    default: vast
    backends:
      vast:
        type: vast
        address: 10.0.0.5
        api_token: my-api-token
        subsystem: openstack-subsystem
        vippool_name: openstack-vips
  backup:
    type: none
  ephemeral:
    type: local

[Copilot]

Pull request overview

Adds a new Cinder volume backend type (vast) to support the VAST Data driver introduced in OpenStack 2026.1, including schema validation, Helm values generation, docs, and release notes.

Changes:

• Introduces VolumeBackendVast (token or username/password auth) and registers it in the VolumeBackend discriminated union.
• Adds unit tests covering VAST backend rendering and credential validation.
• Documents the new backend and adds “VAST” to the Vale vocabulary, plus a release note entry.

Reviewed changes

Copilot reviewed 5 out of 5 changed files in this pull request and generated 2 comments.

Show a summary per file

File	Description
plugins/filter/storage.py	Adds the vast volume backend model and maps it to Cinder driver config keys.
tests/unit/plugins/filter/test_storage.py	Adds tests for token/userpass auth paths, tenant name, and missing-credential validation.
doc/source/deploy/storage.rst	Documents vast backend configuration fields and example YAML.
releasenotes/notes/cinder-vast-data-backend-c4aa359f26d6911e.yaml	Announces the new VAST Data backend support.
.github/styles/config/vocabularies/Base/accept.txt	Adds “VAST” to the Vale accepted vocabulary.

[Copilot]

This test uses pytest.raises(Exception), which can mask unrelated failures and makes the intent unclear. Since StorageConfig.model_validate(...) wraps model-level ValueErrors into a pydantic.ValidationError, assert ValidationError here (and ideally match the message) so you're specifically testing the missing-credentials validation.

Suggested change

	with pytest.raises(Exception):
	with pytest.raises(
	ValidationError, match=r"api_token|san_login|san_password"
	):

[Copilot]

The section title uses "VAST data" while the section body and release note use the product name "VAST Data". Please make the capitalization consistent throughout this section (title + description) so documentation reads consistently and avoids style-lint churn.