OpenStack Glance is a service that provides image discovery, registration, and retrieval functionalities for cloud environments. It allows users to store, catalog, and manage various types of virtual machine (VM) images, such as operating system images, snapshots, and software templates.
The Glance Registry service, also known as the Glance-Registry, is responsible for storing and managing metadata information about the images. It acts as a database for storing image metadata and provides a central registry for images within the OpenStack infrastructure.
Here are the key features and functionalities of the Glance-Registry service:
- Image Metadata Storage: The Glance-Registry service stores image metadata, which includes information like image name, format, size, owner, visibility, and other properties. This metadata helps in efficient image discovery and retrieval.
- Image Registration: When a new image is uploaded to Glance, the Glance-Registry service is responsible for registering and storing its metadata. It assigns a unique identifier (UUID) to each image, which is used for subsequent image operations.
- Image Management: The Glance-Registry service allows users to perform various image management operations. This includes updating image metadata, setting access permissions, associating images with specific projects or tenants, and organizing images into categories or tags.
- Image Search and Discovery: Users can search for images based on their metadata properties like name, format, or tags. The Glance-Registry service provides APIs for querying image metadata and retrieving the list of available images based on specified search criteria.
- Image Lifecycle Management: The Glance-Registry service keeps track of the lifecycle of images, including their creation, modification, and deletion. It ensures that images are properly managed and maintained throughout their lifecycle.
- Image Sharing: Glance-Registry allows image owners to share their images with other projects or tenants within the OpenStack environment. This enables users to collaborate and reuse images across different projects while maintaining access control.
- Security and Access Control: The Glance-Registry service enforces access control policies for images based on user roles and permissions. It ensures that only authorized users or projects can view and manage images based on the defined access policies.
- Integration with Other OpenStack Services: Glance-Registry integrates with other OpenStack services like Nova (Compute service) and Cinder (Block Storage service) to provide seamless image deployment and provisioning capabilities.
In summary, the Glance-Registry service in OpenStack Glance acts as a central repository for image metadata, allowing users to store, register, search, and manage images within the OpenStack environment. It plays a crucial role in enabling efficient image discovery, retrieval, and sharing across different projects or tenants.