Connection settings

The RabbitMQ transport requires a connection string to connect to the RabbitMQ broker, and there are two different styles to choose from. It can accept the standard AMQP URI connection strings, or a custom format documented below.

Specifying the connection string via code

To specify the connection string in code:

var transport = endpointConfiguration.UseTransport<RabbitMQTransport>();
transport.ConnectionString("My custom connection string");

Connection string options

Below is the list of connection string options. When constructing a connection string, these options should be separated by a semicolon.

Host

The host name of the broker.

Port

The port where the broker listens.

Default: 5671 if the UseTls setting is set to true, otherwise the default value is 5672

VirtualHost

The virtual host to use.

Default: /

UserName

The user name to use to connect to the broker.

Default: guest

Password

The password to use to connect to the broker.

Default: guest

UseTls

Indicates if the connection to the broker should be secured with TLS.

Default: false

Transport Layer Security support

Secure connections to the broker using Transport Layer Security (TLS) are supported. To enable TLS support, set the UseTls setting to true in the connection string:

host=broker1;UseTls=true

Client authentication

If the broker has been configured to require client authentication, a client certificate must be specified:

var transport = endpointConfiguration.UseTransport<RabbitMQTransport>();
transport.SetClientCertificate("path", "password");

This can also be done by passing a certificate in directly:

var transport = endpointConfiguration.UseTransport<RabbitMQTransport>();
transport.SetClientCertificate(new X509Certificate2("/path/to/certificate"));

Remote certificate validation

By default, the RabbitMQ client will refuse to connect to the broker if the remote server certificate is invalid. This validation can be disabled with the following setting:

var transport = endpointConfiguration.UseTransport<RabbitMQTransport>();
transport.DisableRemoteCertificateValidation();

External authentication

By default, the broker requires a username and password to authenticate the client, but it can be configured to use other external authentication mechanisms. If the broker requires an external authentication mechanism, the client can be configured to use it with the following setting:

var transport = endpointConfiguration.UseTransport<RabbitMQTransport>();
transport.UseExternalAuthMechanism();

Connecting to multiple cluster nodes

When connecting to a RabbitMQ cluster, it is beneficial if endpoints are able to connect to any of the nodes in the cluster. For example, if a node goes down, the endpoint can attempt to reconnect to a different node and continue operation.

Since endpoint connection strings are limited to specifying a single hostname, the AddClusterNode API can be used to tell the endpoint about additional cluster nodes:

var transport = endpointConfiguration.UseTransport<RabbitMQTransport>();
transport.AddClusterNode("node2", useTls: false);

There is another overload to specify a non-default port:

transport.AddClusterNode("node2", 5675, useTls: true);

Controlling the prefetch count

When consuming messages from the broker, throughput can be improved by having the consumer prefetch additional messages. The prefetch count is calculated by multiplying the maximum concurrency by the prefetch multiplier. The default value of the multiplier is 3, but it can be changed as follows:

var transport = endpointConfiguration.UseTransport<RabbitMQTransport>();
transport.PrefetchMultiplier(4);

Alternatively, the whole calculation can be overridden by setting the prefetch count directly as follows:

var transport = endpointConfiguration.UseTransport<RabbitMQTransport>();
transport.PrefetchCount(100);

Controlling behavior when the broker connection is lost

The RabbitMQ transport monitors the connection to the broker and will trigger the critical error action if the connection fails and stays disconnected for the configured amount of time.

Heartbeat interval

Controls how frequently AMQP heartbeat messages are sent between the endpoint and the broker.

Type: System.TimeSpan

Default: 00:01:00 (1 minute)

var transport = endpointConfiguration.UseTransport<RabbitMQTransport>();
transport.SetHeartbeatInterval(TimeSpan.FromSeconds(30));

Network recovery interval

Controls the time to wait between attempts to reconnect to the broker if the connection is lost.

Type: System.TimeSpan

Default: 00:00:10 (10 seconds)

var transport = endpointConfiguration.UseTransport<RabbitMQTransport>();
transport.SetNetworkRecoveryInterval(TimeSpan.FromSeconds(30));

TimeToWaitBeforeTriggering

Controls the amount of time the transport waits after a failure is detected before triggering the critical error action.

Type: System.TimeSpan

Default: 00:02:00 (2 minutes)

var transport = endpointConfiguration.UseTransport<RabbitMQTransport>();
transport.TimeToWaitBeforeTriggeringCircuitBreaker(TimeSpan.FromMinutes(2));

Debugging recommendations

It can be helpful to increase the heartbeat interval to avoid connection timeouts while debugging:

var transport = endpointConfiguration.UseTransport<RabbitMQTransport>();
transport.SetHeartbeatInterval(TimeSpan.FromMinutes(10));