What is the correct way to start a MassTransit bus when using the CreateRequestClient method? - masstransit

Question

I'm using the following code to send a request/response message between two different processes.
This is the process that "sends" the request:
// configure host
var hostUri = new Uri(configuration["RabbitMQ:Host"]);
services.AddSingleton(provider => Bus.Factory.CreateUsingRabbitMq(cfg =>
{
var host = cfg.Host(hostUri, h =>
{
h.Username(configuration["RabbitMQ:Username"]);
h.Password(configuration["RabbitMQ:Password"]);
});
}));
// add request client
services.AddScoped(provider => provider.GetRequiredService<IBus>().CreateRequestClient<QueryUserInRole, QueryUserInRoleResult>(new Uri(hostUri, "focus-authorization"), TimeSpan.FromSeconds(5)));
// add dependencies
services.AddSingleton<IPublishEndpoint>(provider => provider.GetRequiredService<IBusControl>());
services.AddSingleton<ISendEndpointProvider>(provider => provider.GetRequiredService<IBusControl>());
services.AddSingleton<IBus>(provider => provider.GetRequiredService<IBusControl>());
// add the service class so that the runtime can automatically handle the start and stop of our bus
services.AddSingleton<Microsoft.Extensions.Hosting.IHostedService, BusService>();
Here's the implementation of the BusService:
public class BusService : Microsoft.Extensions.Hosting.IHostedService
{
private readonly IBusControl _busControl;
public BusService(IBusControl busControl)
{
_busControl = busControl;
}
public Task StartAsync(CancellationToken cancellationToken)
{
return _busControl.StartAsync(cancellationToken);
}
public Task StopAsync(CancellationToken cancellationToken)
{
return _busControl.StopAsync(cancellationToken);
}
}
The problem is that when the CreateRequestClient code runs, the bus has not started up yet. Thus the response is never returned from the consumer.
If I replace the host configuration with the following code, I get the desired behavior:
var bus = Bus.Factory.CreateUsingRabbitMq(cfg =>
{
var host = cfg.Host(hostUri, h =>
{
h.Username(configuration["RabbitMQ:Username"]);
h.Password(configuration["RabbitMQ:Password"]);
});
});
bus.Start();
services.AddSingleton(bus);
For some reason, the BusService(IHostedService) executes AFTER the AddScoped delegates.
My question is: what is the correct way to start up the bus before using the CreateRequestClient method? Or is the latter approach to starting up the bus sufficient?