MassTransit–Using RabbitMQ Virtual Hosts

Today I want to talk about a specific feature in RabbitMQ and how we can use this feature with my favorite messaging library MassTransit.

Virtual Hosts

With virtual hosts you can create a logical grouping in  your RabbitMQ cluster. Every exchange, queue, binding, user permissions, and so on is bound to a specific virtual host and isolated from the other virtual hosts. This helps to avoid naming collisions.

There is always at least one virtual host in use; the default one is ‘/’.

To create a new virtual host in your RabbitMQ cluster, you can use the rabbitmqctl's add_vhost command:

rabbitmqctl add_vhost development

Or you can use the RabbitMQ Management portal:

• In the Management Portal go to the Admin tab and click on the Virtual Hosts section on the right:

• Go to the Add Virtual Host form and enter a name and an optional description and tags:

• Click on Add virtual host to create the new virtual host.

Remark: Be aware that virtual hosts are a security boundary, so I would recommend to create different users per virtual host.

Using Virtual Hosts in MassTransit

Now that we have a new Virtual Host created, let’s see how we can use this in MassTransit.

Let’s have a look at a simple example from the MassTransit documentation:

	namespace RabbitMqConsoleListener;
	using System.Threading.Tasks;
	using MassTransit;
	using Microsoft.Extensions.Hosting;
	public static class Program
	{
	public static async Task Main(string[] args)
	{
	await Host.CreateDefaultBuilder(args)
	.ConfigureServices(services =>
	{
	services.AddMassTransit(x =>
	{
	x.UsingRabbitMq((context, cfg) =>
	{
	// The "/" refers to 👇 the virtual host
	cfg.Host("localhost", "/", h =>
	{
	h.Username("guest");
	h.Password("guest");
	});
	});
	});
	})
	.Build()
	.RunAsync();
	}
	}

view raw Program.cs hosted with ❤ by GitHub

In the example above, the virtual host is passed as a second parameter after the servername in the Host() method:

You can also specify it through the URI:

	public static class Program
	{
	public static async Task Main(string[] args)
	{
	// The 'development' part in the URI refers 👇 to the vhost
	var uri=new Uri("rabbitmq://localhost:5672/development");
	await Host.CreateDefaultBuilder(args)
	.ConfigureServices(services =>
	{
	services.AddMassTransit(x =>
	{
	x.UsingRabbitMq((context, cfg) =>
	{
	cfg.Host(uri, h =>
	{
	h.Username("guest");
	h.Password("guest");
	});
	});
	});
	})
	.Build()
	.RunAsync();
	}
	}

view raw Program.cs hosted with ❤ by GitHub