startup2.cs

[assembly: FunctionsStartup(typeof(ConfigTest.Startup))]
namespace ConfigTest
{
    public class Startup : IWebJobsStartup
    {
        public IConfiguration Configuration { get; set; }

        public void Configure(IWebJobsBuilder builder)
        {
            var configurationBuilder = new ConfigurationBuilder();
            configurationBuilder.AddEnvironmentVariables();

            var config = configurationBuilder.Build();
            configurationBuilder.AddAzureAppConfiguration(options =>
            {
                options.Connect(config["AppConfigConnectionString"])
                    .ConfigureRefresh(refresh =>
                    {
                        refresh.Register("QueueName", refreshAll: true)
                            .SetCacheExpiration(TimeSpan.FromSeconds(5));
                    });
            });

            Configuration = configurationBuilder.Build();

            builder.Services.Replace(ServiceDescriptor.Singleton(typeof(IConfiguration), Configuration));
        }
    }
}