Adding health checks to OpenAPI using the new document transformers
In all previous versions of ASP.NET Core (before .NET 9), integrating health checks into your OpenAPI documentation (such as Swagger) was surprisingly challenging – especially when using the MapHealthChecks method. The normal workaround was to create an entire health checks controller just so the Healthchecks endpoint would be mapped to OpenAPI.
With the introduction of the Microsoft.AspNetCore.OpenApi namespace in .NET 9, we now have a more elegant solution. This built-in functionality provides Transformers – powerful new tools that allow us to modify the OpenAPI document directly via the Program.cs file, integrating our HealthCheck without additional controllers.
Getting ready
You can pick up where we left off in the preceding recipe, or clone the starter project here:
