A must-know for anyone looking to prepare for OpenStack advanced interview questions, this is one of the frequent questions asked of content managers. The image service of OpenStack is called Glance, which allows us to discover, register and retrieve virtual images. Using its REST API, we can query the VM image metadata to retrieve the actual image. We can store such virtual machine images in different locations, varying from simple file systems to object-storage systems like OpenStack Object Storage. This service is central to Infrastructure-as-a-Service (IaaS), accepting API requests for disk or server images and metadata definitions from end users. Not only this, but we can also store the disk or server images on various repository types, including OpenStack Object Storage.  OpenStack image services have different components-  glance-api- that will accept the API calls for discovering, retrieving, and storing the images.  glance-registry will allow us to store, process, and retrieve the metadata about images.   Database- stores the image metadata. We can use databases like- MySQL or SQLite.  Storage repository for image files- it supports various storage repos, such as file systems, Object Storage, RADOS block devices, VMware datastore, and HTTP.  Metadata definition service- includes common API for vendors, admins, services, and users to define their own custom metadata meaningfully.