You can obtain Esri virtual machine images from the Microsoft Azure Marketplace. Images contain ArcGIS Server, Portal for ArcGIS, ArcGIS Data Store, and ArcGIS Web Adaptor (IIS) and create machines that use a Windows Server 2016 operating system.
Use these images along with ArcGIS Enterprise Cloud Builder for Microsoft Azure and your ArcGIS Server and Portal for ArcGIS licenses to deploy ArcGIS Enterprise, ArcGIS Image Server, ArcGIS GeoAnalytics Server, ArcGIS GeoEvent Server, and stand-alone GIS Server sites on the Azure cloud.
Go to Microsoft Azure Marketplace and search for arcgis or esri to find the images. Download them to your Microsoft Azure subscription.
Next, install ArcGIS Enterprise Cloud Builder for Microsoft Azure and deploy a site.
Microsoft Azure Government
The ArcGIS 10.3.1 and 10.5.x images are available in the Microsoft Azure Government cloud environment.
Microsoft Azure Government is a United States (U.S.) government-community cloud that offers hyperscale compute, storage, networking, and identity management services, with world-class security. A physical and network-isolated instance of Microsoft Azure, operated by screened U.S. personnel, Azure Government enables new forms of cross-agency collaboration and rich cloud service integration. For more information, see http://azure.microsoft.com/en-us/features/gov/.
If you want to deploy on the Azure Government cloud environment and have an Azure Government account, check the U. S. Government account option on the landing page of Cloud Builder before you sign in to your Azure subscription.