Description

Microsoft's powerfull ASP.NET Core configuration extensions are also available for .Net 4.7 projects.
To make use of it for .Net 4.x in conjuction with the old App.config/Web.config sources you need a custom provider like this project.

(microsoft docs)

Usage

NuGet Installation

From Visual Studio's Package Manager Console:

PM> Install-Package Lz.Microsoft.Configuration.LegacyProvider

In code

IConfigurationBuilder configBuilder = new Microsoft.Extensions.Configuration.ConfigurationBuilder()
	.SetBasePath(Directory.GetCurrentDirectory())
	// ...
	// With defaults section separators (.,-):
	.AddLegacyConfig()
	// Or with custom section separators:
	.AddLegacyConfig((new string[] {"."})
	// ...
	//.AddCommandLine(args)
;
IConfigurationRoot config = configBuilder.Build();
var appSettings = config.Get<MySettings>();

Benefits

The benefits of using Microsoft.Extensions.Configuration over the old System.Configuration.ConfigurationManager are:

• Configuration binding to typed classes.
• Adds support for multiple configuration sources with 1 line of code (CommandLine, Json, Xml, Ini, EnvironmentVariables, User-Secrets tool, Azure, etc).
• Easily customizable configuration sources.
• Progressive migration from dotNet 4.X to Core.

Thanks to Ben Foster for his original post.