From .NET 6 to .NET 8, my migration experience: Using OpenApi on Azure Function on .NET 8 isolated

Introduction

I recently migrated an Azure function based on HttpTriggers. This function was running on .NET 6 in-process, and I migrated it to .NET 8 isolated. The only option available since Microsoft will only support isolated mode and no more in-process for Azure functions. In this post, I will show you the necessary modifications regarding OpenApi and Swagger.

Changes to make

Like all migrations from .NET in-process to .NET isolated, you must first upgrade the Nuget packages. In the in-process mode, all Nuget packages containing the keyword “WebJob” must be replaced by the same package by replacing “WebJob” with “Functions.Worker” as follows:

Microsoft.Azure.WebJobs.{feature} -> Microsoft.Azure.Functions.Worker.{feature}

Therefore the Nuget OpenApi package for Azure functions is transformed from Microsoft.Azure.WebJobs.Extensions.OpenApi to Microsoft.Azure.Functions.Worker.Extensions.OpenApi

The code remains exactly the same as follows:

Don’t forget to activate OpenAPI with the ConfigureOpenApi extension in your Program.cs as follows:

You will notice something weird: The namespace won’t change and will remain “Microsoft.Azure.WebJobs.Extensions.OpenApi.Core.Attributes”. It’s normal Microsoft hasn’t changed the namespace and there no more Nuget package named “WebJob”:

Let’s run it

If we run it, you’ll see that it’s working like a charm, you can find in the output console the endpoints generated by the OpenAPI Nuget package:

You can invoke the Swagger URL for example as follows:

As you can see, it works fine, and you don’t have to worry about the “WebJob” namespace.

Enjoy your migration 🙂