How To Identify Unavailable AWS Instance Types in DescribeInstanceTypes API

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If you’re running into issues with AWS EC2 instance types not showing up or getting errors like “does not exist,” the problem is likely related to misunderstanding how the DescribeInstanceTypes API works. This API isn’t global for your entire AWS account—it’s specific to each region. That means you have to specify the correct region when you make your API calls.

By default, your SDK or command line interface (CLI) often uses a preset region, which might be different from the one where your instances or certain instance types are available. This can cause confusion because when you query for instance types, you only see what’s available in that default region—not across your whole account.

Here’s what’s happening:

Suppose you’re looking for the m8azn.12xlarge instance type. You run DescribeInstanceTypeOfferings in Region A where this type is available. But if you then run DescribeInstanceTypes in Region B, where this instance type isn’t supported, you’ll see a “does not exist” error even though it is available elsewhere. Different regions have different available instance types.

The same applies if you have a p2.xlarge instance running in one region but query in another region where that type isn’t offered. Since EC2 regions vary, this mismatch causes errors.

The solution is straightforward: always specify the region explicitly when calling the API. Make sure the region you’re querying matches where your instances are located or where you’re checking for available instance types. If you want information across multiple regions, you’ll need to make separate calls for each one.

Remember, the API is designed to show information only for the region you specify. If you don’t, you risk seeing incomplete or no results, even though the instance types are available in other regions.

For more detailed info, you can check the official AWS documentation on how to correctly use DescribeInstanceTypes and related APIs. It explains that the API is designed to work region-specific and why it’s essential to specify the region when making your calls.