title: What is the best approach for user defined configuration data under ASP.net CORE?
body: <p>We are just getting started to convert our ASP.Net based application to .Net CORE. One decision we need to make now is what configuration file format we should use. In our current ASP.Net based app, we use web.config file's AppSettings for our application configuration data. But with ASP.Net core, things look much different now. The AppSettings, for instance, is no longer supported by web.config. Although the &quot;environmentVariable&quot; property of the new web.config seems support user config data, that doesn't seem to be the only ways for doing that. According to <a href="https://docs.microsoft.com/en-us/aspnet/core/fundamentals/configuration/?view=aspnetcore-5.0" rel="nofollow noreferrer">this article</a>, Json configurations file, XML file, and even ini file can all be used for application/user configuration purpose. Can someone tell me if it is a bad idea if I keep using web.config file for our application configuration under .net CORE? What's the downsides of doing so? and why should I chose one over the others?</p>