Feature Overview

https://blueprints.launchpad.net/glance/+spec/download-from-specific-store

Right now when you download an image using GET /v2/images/{image_id}/file,
Glance tries the default store first. If the image is not there, it tries
other stores until it finds the image. This spec adds a way to tell Glance
which stores to use. You can give a list of stores you want to try. This
helps compute nodes and services like Nova and Cinder download from stores
that are close to them.

Goals 

• Deliver spec 
• Deliver to upstream
• Deliver to downstream with documentation and CI automated coverage
• Provide Support enablement

Done - Acceptance Criteria 

• Feature delivered downstream with customer facing docs, CI regression coverage and support enablement

Use Cases

Services can find available stores using existing APIs like GET /v2/info/stores
and GET /v2/info/stores/detail. These show store names, descriptions, types,
and properties that help decide which store to use.

1. Performance: A compute node can download from a local store instead of a remote one
2. Proximity: Edge compute nodes can download from stores close to them (like "us-east" or "eu-west")
3. Testing: Operators can test if a specific store works
4. Load distribution: Spread downloads across stores so one store does not get too much load

Out of Scope 

Documentation Considerations 

• Feature will need customer facing docs for configuration and context usage

Questions to Answer 

• None so far

Background and Strategic Fit

This feature enhances our capabilities for DZ and DCN based deployments and Edge use cases.  DZ is a popular approach for our RHOSO 18 enterprise customers.

Customer Considerations 

This feature should be available in DZ and DCN deployments