Advanced Data Solutions : Compute Platform Versions for Azure API management service

Background Information:

For Azure API Management (APIM) service users, you may notice that we've been upgrading the API Management compute platform version - the Azure compute resources that host the service - for instance in several service tiers, in order to enhance service capabilities.

This article gives you context about the upgrade from platform version stv1 to stv2, and the major differences between these compute platforms. The following parts will be explained:

Available Compute Platform Versions
For APIM already in use, how to find the platform version in use?
For newly created APIM, how to specify the platform version you want (stv1 or stv2)?
Difference between stv1 and stv2

Available Compute Platform Versions

Currently, there are 3 platform versions: stv1, stv2, and mtv1.

For consumption tier APIM, the architecture uses App service, and the platform version will be mtv1 only.

For other tiers (Developer, Basic, Standard, and Premium), there are stv1 and stv2 platform versions. Version stv2 uses Virtual machine scale sets , while stv1 uses Cloud Service (classic).

Version	Description	Architecture	API Management tiers
stv2	Single-tenant v2	Virtual machine scale sets	Developer, Basic, Standard, and Premium
stv1	Single-tenant v1	Cloud Service (classic)	Developer, Basic, Standard, and Premium
mtv1	Multi-tenant v1	App service	Consumption

Reference to Compute platform architecture: https://docs.microsoft.com/en-us/azure/api-management/compute-infrastructure

For APIM already in use, how to find the platform version in use?

Starting with API version 2021-04-01-preview, the API Management instance has a read-only PlatformVersion property that shows this platform information.

Example API link: https://docs.microsoft.com/en-us/rest/api/apimanagement/2021-04-01-preview/api-management-service/get#apimanagementservicegetservice

For newly created APIM, how to specify the platform version you want (stv1 or stv2)?

To better clarify all the scenarios, you can refer to the flow chart below:

Based on the above chart:

1. If you create an APIM without Virtual Network, the newly created APIM would be VMSS based, which is stv2 PlatformVersion.

2. If you create an APIM within Virtual Network, you can only create a VMSS based APIM(stv2) when all the below requirements have been met:

you’ve configured the APIM with your own public IPv4 address or the Availability Zone

create the new APIM service using Azure portal, or specifying API version 2021-01-01-preview or later (using Azure REST API, ARM template, etc.)

3. Otherwise, the newly created APIM would be Cloud Service based, which is stv1 version.

Difference between stv1 and stv2

There would be some key differences between stv1 and stv2 when your APIM is deployed in the Virtual Network.

Version stv2	Version stv1
A virtual network and subnet in the same region and subscription as your API Management instance. The subnet may contain other Azure resources.	A virtual network and subnet in the same region and subscription as your API Management instance. Also, the subnet must be dedicated to API Management instances.
A Standard SKU public IPv4 address. The public IP address resource is required when setting up the virtual network for either external or internal access.	Your own public IP address is not required
Requires service endpoint of: 1. Azure SQL 2. Azure Storage 3. Azure Event Hub 4. Azure Key Vault	Requires service endpoint of: 1. Azure SQL 2. Azure Storage 3. Azure Event Hub
Requires port 443 outbound to access Azure Key Vault	Doesn't require access Azure Key Vault