Openstack Glance is an image service that allows discovery, registration, and retrieval of virtual machine images. It has a RESTful API to query image metadata and retrieve images. Images can be stored in various locations like file systems or object storage. Glance consists of components like the Glance API, registry, database, and stores that support different storage backends. It supports various disk and container formats for images.

1. Openstack Glance

2. Openstack Glance
Glance image service include discovering, registering and retrieving virtual
images. Glance has a RESTful API that allows querying of VM image metadata
as well as retrieval of the actual image.
VM images made available through glance can be stored in variety of locations
from simple file system to object storage systems.

3. Glance Components
rbd
swift
file system
s3

4. Glance Components
Glance-api: Accepts image API calls for image discovery, retrieval and storage.
Glance-registry: Stores, processes and retrieve metadata about images.
Glance database: Stores image metadata and we can choose our database
depending on preference. Most deployments use MySQL or SQLite.
Glance store: Glance supports normal file systems, RADOS Block Devices,
Amazon S3, Swift.

5. Glance Architecture

6. Glance Formats
Disk Formats
-raw (unstructured)
-qcow2 (Qemu)
-iso (optical)
-vhd, vmdk, vdi (Hyper-V, Esxi, Virtualbox)
-aki, ari, ami (amazon images)

7. Glance Formats
Container Formats
-bare
-OVF
-aki, ari, ami

8. $ glance image-create --name "cirros-0.3.4-x86_64" --file /tmp/images/cirros-0.3.4-
x86_64-disk.img
--disk-format qcow2 --container-format bare --visibility public --progress
Progress : Show upload progress bar.

9. [
[=============================>] 100%
+-----------------------------+-----------------------------------------------------------+
| Property | Value
|
+-----------------------------+-----------------------------------------------------------+
| checksum | 133eae9fb1c98f45894a4e60d8736619 |
| container_format | bare |
| created_at | 2015-03-26T16:52:10Z |
| disk_format | qcow2
|
| id | 38047887-61a7-41ea-9b49-27987d5e8bb9 |
| min_disk | 0
|
| min_ram | 0
|
| name | cirros-0.3.4-x86_64 |
| owner | ae7a98326b9c455588edd2656d723b9d |
| protected | False
|
| size | 13200896
|
| status | active |

10. Glance status flow

11. # glance image-list
+--------------------------------------------------------------+---------------------------+
| ID |
Name |
+--------------------------------------------------------------+---------------------------+
| 38047887-61a7-41ea-9b49-27987d5e8bb9 | cirros-0.3.4-x86_64 |
+--------------------------------------+-----------------------+---------------------------+

12. Glance Configuration Files
glance-api.conf : Configuration file for image service API.
glance-registry.conf : Configuration file for image service registry, which stores
the metadata about images.
glance-scrubber.conf : Utility for the image service that cleans up images that
have been deleted.
policy.json : Additional access control that apply to image service.

13. Openstack image & instance

14. Glance commands
# glance image-list
# glance image-show <image-id>
# glance image-delete <image-id>

15. THANKS