/// <summary>
/// The program's main start/entry point. Hold on to your butts .... here we go!
/// </summary>
/// <typeparam name="T">Startup class type.</typeparam>
/// <param name="args">Optional command line arguments.</param>
/// <returns>Task of this Main application run.</returns>
public static async Task Main <TStartup>(string[] args) where TStartup : class
{
var options = new MainOptions <TStartup>
{
CommandLineArguments = args
};
await Main(options);
}
public static IHostBuilder CreateHostBuilder <TStartup>(MainOptions <TStartup> options) where TStartup : class
{
var hostBuilder = Host
.CreateDefaultBuilder(options.CommandLineArguments)
.ConfigureLogging((context, logging) =>
{
// Don't want any of the default crap.
logging.ClearProviders();
})
.UseSerilog();
var logger = new SerilogLoggerProvider(Log.Logger).CreateLogger(nameof(Program));
hostBuilder
.ConfigureWebHostDefaults(webBuilder =>
{
if (options.StartupActivation is null)
{
// Normal startup class with default constructor.
webBuilder.UseStartup <TStartup>();
}
else
{
// Use the custom startup activation function, instead.
// REF: https://docs.microsoft.com/en-us/aspnet/core/release-notes/aspnetcore-5.0?view=aspnetcore-5.0#control-startup-class-activation
// (Pro Tip: this is a great way to add logging, to Startup.cs !!! YES!!!! )
//webBuilder.UseStartup(c => new TStartup(c));
webBuilder.UseStartup(context => options.StartupActivation(context, logger));
// The startup class (activated, above) will be activated in _this_ assmebly and not the main host/app assembly.
// This means that when things like 'MapControllers' tries to do an assembly scan (the default functionality)
// in the host/app assembly, it will FAIL to find any.
// As such, we actually need to really reset the main ApplicationKey to say it's for the provided startup class.
// Hat tip to: @aarondandy, @buildstarted and @xt0rted
var startupAssemblyName = options.StartupActivation.GetMethodInfo().DeclaringType !.GetTypeInfo().Assembly.GetName().Name;
webBuilder.UseSetting(WebHostDefaults.ApplicationKey, startupAssemblyName);
}
});
return(hostBuilder);
}
/// <summary>
/// The program's main start/entry point. Hold on to your butts .... here we go!
/// </summary>
/// <typeparam name="T">Startup class type.</typeparam>
/// <param name="options">Options to help setup/configure your program.</param>
/// <returns>Task of this Main application run.</returns>
public static async Task Main <TStartup>(MainOptions <TStartup> options) where TStartup : class
{
try
{
if (options is null)
{
throw new ArgumentNullException(nameof(options));
}
// Before we do _ANYTHING_ we need to have a logger so we can start
// seeing what is going on ... good or bad.
Log.Logger = new LoggerConfiguration()
.ReadFrom.Configuration(GetConfigurationBuilder())
.Enrich.FromLogContext()
.CreateLogger();
// Display any (optional) initial banner / opening text to define the start of this application now starting.
if (!string.IsNullOrWhiteSpace(options.FirstLoggingInformationMessage))
{
Log.Information(options.FirstLoggingInformationMessage);
}
if (options.LogAssemblyInformation)
{
var assembly = typeof(TStartup).Assembly;
var assemblyDate = string.IsNullOrWhiteSpace(assembly.Location)
? "-- unknown --"
: File.GetLastWriteTime(assembly.Location).ToString("u");
var assemblyInfo = $"Name: {assembly.GetName().Name} | Version: {assembly.GetName().Version} | Date: {assemblyDate}";
Log.Information(assemblyInfo);
}
var host = CreateHostBuilder(options).Build();
// Ok, now lets go and start!
await host.RunAsync();
}
catch (Exception exception)
{
const string errorMessage = "Something seriously unexpected has occurred while preparing the Host. Sadness :~(";
// We might NOT have created a logger ... because we might be _trying_ to create the logger but
// we have some bad setup-configuration-data and boom!!! No logger successfully setup/created.
// So, if we do have a logger created, then use it.
if (Log.Logger is Logger)
{
// TODO: Add metrics (like Application Insights?) to log telemetry failures -IF- Serilog can't do this adequately.
Log.Logger.Fatal(exception, errorMessage);
}
else
{
// Nope - failed to create a logger and we have a serious error. So lets
// just fall back to the Console and _hope_ someone can read/access that.
Console.WriteLine(_explosion);
Console.WriteLine(errorMessage);
Console.WriteLine();
Console.WriteLine();
Console.WriteLine($"Error: {exception.Message}");
Console.WriteLine();
}
}
finally
{
var shutdownMessage = string.IsNullOrWhiteSpace(options.LastLoggingInformationMessage)
? "Application has now shutdown."
: options.LastLoggingInformationMessage;
// Again: did we successfully create a logger?
if (Log.Logger is Logger)
{
Log.Information(shutdownMessage);
// Ensure to flush and stop internal timers/threads before application-exit (Avoid segmentation fault on Linux)
Log.CloseAndFlush();
}
else
{
Console.WriteLine(shutdownMessage);
}
}
}