glance image services

Glance functionality

  • 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 Archirecture

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:
  • Create/read/update/delete
  • Query image via filters such as name, Container format, Disk format,size_min, size_max and status.

      Catching images

  • 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

       Glance

  • 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.

Open Stack Installation Tutorial for Ubuntu……..