I'm working on an Azure Function App (v2), which has a number of different functions inside the same Function App.
It is going to be deployed in multiple Azure regions, and I would like to add a custom header, that indicates which region served the request.
I know that I can let each function return HttpResponseMessage which can contain custom headers. Instead of duplicating that code to each function, I would like to make it centralized in the entire Function App project. Another drawback of returning HttpResponseMessage is that I would like to use IActionResult, so I can use JsonResult or OkObjectResult and similar return types.
With an ASP.NET MVC project, I could add a middleware which added the header or add the headers using web.config. Neither seems to be possible in a Function App.
How can this be done without having to return HttpResponseMessage and adding the header inside each function's Run method?
