The middleware in ASP.NET Core is useful because it allows new features to be added without affecting the original behavior.

When developing an application using ASP.NET Core, you may want to know the configuration values registered in Microsoft.Extensions.Configuration.IConfiguration .

For example, if you are developing microservices using YAML files.

I have published a NuGet package called Enviewer to help myself. This will make it easier to see the configuration values of IConfiguration.

https://www.nuget.org/packages/Enviewer/

Getting Started

1. Install the standard Nuget package into your ASP.NET Core application.
   

   Package Manager : Install-Package Enviewer -Version 1.0.0
   CLI : dotnet add package Enviewer --version 1.0.0
   

2. In the Configure method of Startup.cs, insert middleware.
   

   app.UseEnviewer();
   

   By accessing /enviewer in your browser, you can view all the environment variables registered in Microsoft.Extensions.Configuration.IConfiguration.

   

I used these documents when I developed my package.

Write custom ASP.NET Core middleware | Microsoft Docs

Test ASP.NET Core middleware | Microsoft Docs