Akka.Hosting - Dependancy Injection in Actor parameter

How to inject parameters to Actors using Akka.Hosting? i.e. public ExampleActor(Service1 service){ _service = service; .... }

Service1 is a Service added to IServiceCollection during startup.

You can use Akka.DependencyInjection with Akka.Hosting via the following syntax:

// arrange
using var host = await StartHost(collection =>
{
    collection.AddAkka("MyActorSys", (builder, sp) =>
    {
        builder.WithActors((system, registry, resolver) =>
        {
            var singletonActor = system.ActorOf(resolver.Props<SingletonActor>(), "singleton");
            registry.TryRegister<SingletonActor>(singletonActor);
        });
    });
});

// act
var singletonInstance = host.Services.GetRequiredService<IMySingletonInterface>();
var singletonActor = host.Services.GetRequiredService<ActorRegistry>().Get<SingletonActor>();
var singletonFromActor =
    await singletonActor.Ask<IMySingletonInterface>(SingletonActor.GetSingleton.Instance, TimeSpan.FromSeconds(3));

// assert
singletonFromActor.Should().Be(singletonInstance);

The WithActors line has an overload which exposes the DependencyResolver - that uses the IServiceProvider under the hood and you can use DependencyResolver.Props<TActor>(non-DI'd arguments...) to instantiate an actor that resolves dependencies through its constructor.