Glance provides the heart of virtual machine management for OpenStack. Most cloud services will provide some degree of virtualization and will have an analog resource similar to Glance. The image service API is a RESTful service and lets a customer develop VM templates, discover available VMs, clone images to other servers, register VMs, and even move running virtual machines to different physical servers without interruption. Glance calls into Swift (the object store) to retrieve or store different images. Glance supports different styles of virtual images:

• raw: Unstructured images
• vhd: VMWare, Xen, Oracle VirtualBox
• vmdk: Common disk format
• vdi: QEMU emulator image
• iso: Optical drive image (CD ROM)
• aki/ari/ami: Amazon image