public static IHostBuilder CreateHostBuilder(string[] args) =>
		Host.CreateDefaultBuilder(args)
				.ConfigureAppConfiguration(config => {
						config.AddJsonFile("mysettings.json", 
						optional: true, reloadOnChange: true);
				})
				.ConfigureWebHostDefaults(webBuilder =>
				{
						webBuilder.UseSetting("oneSet", "SuperIronMan");
						webBuilder.UseStartup<Startup>();
				});

使用配置

app.UseEndpoints(endpoints =>
{
    endpoints.MapGet("/", async context =>
    {
        await context.Response.WriteAsync($"Read Node FromSource={Configration["FromSource"]}");
    });
});