Akka.Cluster.Hosting 0.4.0

Akka.Hosting

BETA: this project is currently in beta status as part of the Akka.NET v1.5 development effort, but the packages published in this repository will be backwards compatible for Akka.NET v1.4 users.

HOCON-less configuration, application lifecycle management, ActorSystem startup, and actor instantiation for Akka.NET.

Consists of the following packages:

1. Akka.Hosting - core, needed for everything
2. Akka.Remote.Hosting - enables Akka.Remote configuration
3. Akka.Cluster.Hosting - used for Akka.Cluster, Akka.Cluster.Sharding
4. Akka.Persistence.SqlServer.Hosting - used for Akka.Persistence.SqlServer support.
5. Akka.Persistence.PostgreSql.Hosting - used for Akka.Persistence.PostgreSql support.

See the "Introduction to Akka.Hosting - HOCONless, "Pit of Success" Akka.NET Runtime and Configuration" video for a walkthrough of the library and how it can save you a tremendous amount of time and trouble.

Summary

We want to make Akka.NET something that can be instantiated more typically per the patterns often used with the Microsoft.Extensions.Hosting APIs that are common throughout .NET.

using Akka.Hosting;
using Akka.Actor;
using Akka.Actor.Dsl;
using Akka.Cluster.Hosting;
using Akka.Remote.Hosting;

var builder = WebApplication.CreateBuilder(args);

builder.Services.AddAkka("MyActorSystem", configurationBuilder =>
{
    configurationBuilder
        .WithRemoting("localhost", 8110)
        .WithClustering(new ClusterOptions(){ Roles = new[]{ "myRole" },
            SeedNodes = new[]{ Address.Parse("akka.tcp://MyActorSystem@localhost:8110")}})
        .WithActors((system, registry) =>
    {
        var echo = system.ActorOf(act =>
        {
            act.ReceiveAny((o, context) =>
            {
                context.Sender.Tell($"{context.Self} rcv {o}");
            });
        }, "echo");
        registry.TryRegister<Echo>(echo); // register for DI
    });
});

var app = builder.Build();

app.MapGet("/", async (context) =>
{
    var echo = context.RequestServices.GetRequiredService<ActorRegistry>().Get<Echo>();
    var body = await echo.Ask<string>(context.TraceIdentifier, context.RequestAborted).ConfigureAwait(false);
    await context.Response.WriteAsync(body);
});

app.Run();

No HOCON. Automatically runs all Akka.NET application lifecycle best practices behind the scene. Automatically binds the ActorSystem and the ActorRegistry, another new 1.5 feature, to the IServiceCollection so they can be safely consumed via both actors and non-Akka.NET parts of users' .NET applications.

This should be open to extension in other child plugins, such as Akka.Persistence.SqlServer:

builder.Services.AddAkka("MyActorSystem", configurationBuilder =>
{
    configurationBuilder
        .WithRemoting("localhost", 8110)
        .WithClustering(new ClusterOptions()
        {
            Roles = new[] { "myRole" },
            SeedNodes = new[] { Address.Parse("akka.tcp://MyActorSystem@localhost:8110") }
        })
        .WithSqlServerPersistence(builder.Configuration.GetConnectionString("sqlServerLocal"))
        .WithShardRegion<UserActionsEntity>("userActions", s => UserActionsEntity.Props(s),
            new UserMessageExtractor(),
            new ShardOptions(){ StateStoreMode = StateStoreMode.DData, Role = "myRole"})
        .WithActors((system, registry) =>
        {
            var userActionsShard = registry.Get<UserActionsEntity>();
            var indexer = system.ActorOf(Props.Create(() => new Indexer(userActionsShard)), "index");
            registry.TryRegister<Index>(indexer); // register for DI
        });
})

ActorRegistry

As part of Akka.Hosting, we need to provide a means of making it easy to pass around top-level IActorRefs via dependency injection both within the ActorSystem and outside of it.

The ActorRegistry will fulfill this role through a set of generic, typed methods that make storage and retrieval of long-lived IActorRefs easy and coherent:

var registry = ActorRegistry.For(myActorSystem); // fetch from ActorSystem
registry.TryRegister<Index>(indexer); // register for DI
registry.Get<Index>(); // use in DI