What is a Shared Image Gallery?
The Shared Image Gallery is a repository for images that can be used to create VMs. The repository can be shared across subscriptions, regions and tenants. The Shared Image Gallery is a service that is part of the Azure Compute service. If you have a large number of images that you need to maintain, and would like to make them available throughout multiple subscriptions or tenants, you can use an Azure Compute Gallery as a repository.
What are Images
An image is a copy of either a full VM (including any attached data disks) or just the OS disk, depending on how it is created. When you create a VM from the image, a copy of the VHDs in the image are used to create the disks for the new VM. The image remains in storage and can be used over and over again to create new VMs.
Image definitions
Image definitions are created within a gallery and they carry information about the image and any requirements for using it to create VMs. This includes whether the image is Windows or Linux, release notes, and minimum and maximum memory requirements. It is a definition of a type of image.
Image versions
An image version is what you use to create a VM. You can have multiple versions of an image as needed for your environment. When you use an image version to create a VM, the image version is used to create new disks for the VM. Image versions can be used multiple times.
Sharing options
You can share the Shared Image Gallery using three different options:
- Direct sharing using the Azure RBAC model
- Sharing with specific subscriptions or tenants
- Sharing with everyone publicly