This chapter covers the configuration of an ASP.NET Core application. Every application needs configuration in one form or another because it makes it much easier to change the underlying behavior should anything happen—think about connection strings, credentials, Internet Protocol (IP) addresses, or any other kind of data that can change over time and is therefore not appropriate to be hardcoded.

Configuration can be done in many ways, some of which don't even require redeploying your application, which is a huge benefit. Luckily, .NET Core was conceived with this in mind and is also very extensible, so it can cover most scenarios, basic and advanced. It also plays nicely with other aspects, such as security and dependency injection.

Also, a very typical configuration just features switching or toggling: something is either enabled or not. .NET Core 3 introduced a new feature toggling...