Extensions.Hosting.AsyncInitialization

A simple helper to perform async application initialization for the generic host in .NET 6.0 or higher (e.g. in ASP.NET Core apps).

Usage

1. Install the Extensions.Hosting.AsyncInitialization NuGet package:

   Command line:

   dotnet add package Extensions.Hosting.AsyncInitialization
   

   Package manager console:

   Install-Package Extensions.Hosting.AsyncInitialization
   

2. Create a class (or several) that implements IAsyncInitializer. This class can depend on any registered service.

   public class MyAppInitializer : IAsyncInitializer
   {
       public MyAppInitializer(IFoo foo, IBar bar)
       {
           ...
       }
   
       public async Task InitializeAsync(CancellationToken cancellationToken)
       {
           // Initialization code here
       }
   }
   

3. Register your initializer(s) in the same place as other services:

       services.AddAsyncInitializer<MyAppInitializer>();
   

4. In the Program class, make the Main method async and change its code to initialize the host before running it:

   public static async Task Main(string[] args)
   {
       var host = CreateHostBuilder(args).Build();
       await host.InitAsync();
       await host.RunAsync();
   }
   

   You can also pass a CancellationToken in order to propagate notifications to cancel the initialization if needed.

   In the following example, the initialization will be cancelled when Ctrl + C keys are pressed :

   public static async Task Main(string[] args)
   {
       using CancellationTokenSource cancellationTokenSource = new CancellationTokenSource();
   
       // The following line will hook `Ctrl` + `C` to the cancellation token. 
       Console.CancelKeyPress += (source, args) => cancellationTokenSource.Cancel();
   
       var host = CreateHostBuilder(args).Build();
   
       await host.InitAsync(cancellationTokenSource.Token);
       await host.RunAsync();
   }
   

This will run each initializer, in the order in which they were registered.