Generic Host multiple endpoint hosting

Code walk-through

This sample shows how to host multiple endpoints in one generic host process by using multiple IHostBuilder instances. When started, the application creates two host builder instances, each configured for a different endpoint that could be using a different configurations:

using(var endpointOneBuilder = ConfigureEndpointOne(Host.CreateDefaultBuilder(args)).Build())
using(var endpointTwoBuilder = ConfigureEndpointTwo(Host.CreateDefaultBuilder(args)).Build())
{
    await Task.WhenAll(endpointOneBuilder.StartAsync(), endpointTwoBuilder.StartAsync());
    await Task.WhenAll(endpointOneBuilder.WaitForShutdownAsync(), endpointTwoBuilder.WaitForShutdownAsync());
}

An important thing to keep in mind is that dependency injection is used internally to register components, handlers, and sagas. Each host has a separate ServiceProvider which means the containers are not shared between the endpoints.

To ensure that each endpoint instance registers only its own components like message handlers, it is important to specify an assembly scan policy using one of the supported approaches.

In this example, complete isolation is required between the two endpoints so that the types from Instance2 are excluded from Instance1 and vice versa.

var endpointConfiguration = new EndpointConfiguration("Instance1");
var scanner = endpointConfiguration.AssemblyScanner();
scanner.ExcludeAssemblies("Instance2");