Priority order of configuration

Overview

In the default ASP.NET app builder, the configuration providers are added in this order:

var env = hostingContext.HostingEnvironment;

config.AddJsonFile("appsettings.json", optional: true, reloadOnChange: true)
      .AddJsonFile($"appsettings.{env.EnvironmentName}.json", optional: true, reloadOnChange: true);

if (env.IsDevelopment())
{
    var appAssembly = Assembly.Load(new AssemblyName(env.ApplicationName));
    if (appAssembly != null)
    {
        config.AddUserSecrets(appAssembly, optional: true);
    }
}

config.AddEnvironmentVariables();

if (args != null)
{
    config.AddCommandLine(args);
}

The more specific the settings, the later they're loaded and the higher priority (as they will override existing settings).