- Provides discovery, registration and delivery services for disk and server images.
- Open stack compute deploys VM’s from snap shots of installed and configured VM’s – called images
- Ability to copy or snapshot a server image and immediately store it away
- Users can choose from available images and immediately store It away
- Stored images can be used as template to get the new instance up and running quickly and consistently
- API accessed from a standard REST interface
- It supports the storage and cataloging of snapshots enabling virtual machines to be backed up quickly
Glance-api: allows query of VM image metadata and retrieve the actual image with HTTP request
Glance-Storage adapter: Provides interface between glance and vendor-specific devices for performing image saving, retrieval, deletion and verification
Glance-Database: Stores images-related information such as l location of the images, image properties and image membership.
Glance-Registry: Stores and retrieves metadata about images.
Includes a RESTful API that allows users to query VM image metadata and retrieve the actual image with HTTP request.Glance features
- Image Operations:
- Query image via filters such as name, Container format, Disk format,size_min, size_max and status.
- Uses SQLLite or filesystem that supports xattrs (extended file and directory attributes) for catching
- Pre-fetch images.
- Cleans invalid cache entries
Glance-supported backend stores
Types of glance supported storage backend used to store disk images, include:
- Swift: the high availbel object storage project in openstack
- Cinder: the block storage project in openstack
- Filesystem: writes image files to the local filesystem.
- S3: allows glance to store images in Amazon S3 service.
- HTTP: VM images that are avialble via HTTP somewhere on the internet. This store as read only
Glance CLI commands
- Image-create : create new image
- Image-delete : delete specified image
- Image-download: download a specific image
- Image-list : list images you can access
- Image-show: describe a specific image
- Image-update: update a specific image
- Member-create: share a specific image with tenant
- Member-delete: delete a specific image from tenant
- Member-list: describe sharing permissions by image or tenant.