# Prometheus Metrics

MassTransit.Prometheus (opens new window)

MassTransit supports Prometheus metric capture, which provides useful observability into the bus, endpoints, consumers, and messages.

The prometheus-net library is used as the Prometheus client since it is mentioned on the Prometheus client list.

# Configuration

To configure the bus to capture metrics, add the UsePrometheusMetrics() method to your bus configuration.

public void ConfigureServices(IServiceCollection services)
{
    // this registration is simplified
    services.AddMassTransit(x =>
    {
        x.UsingRabbitMq((context, cfg) =>
        {
            cfg.UsePrometheusMetrics(serviceName: "order_service");
        });
    });
}

# Publishing Metrics

Metrics must be available on an HTTP endpoint, by default it is /metrics. Add the ASP.NET Core integration package to get this endpoint out-of-the-box.

TIP

To publish metrics so that they can be scraped by Prometheus, an ASP.NET Core Generic Host is recommended, with the Kestrel HTTP server configured.

dotnet add package prometheus-net.AspNetCore

And then, add the metric server to the application builder.

public void Configure(IApplicationBuilder app)
{
    app.UseMetricServer();
}

For more details, see the Prometheus-Net Documentation (opens new window).

# Metrics Captured

The metrics captured by MassTransit are listed below.

Name Description
mt_receive_total Total number of messages received
mt_receive_fault_total Total number of messages receive faults
mt_receive_duration_seconds Elapsed time spent receiving messages, in seconds
mt_receive_in_progress Number of messages being received
mt_consume_total Total number of messages consumed
mt_consume_fault_total Total number of message consume faults
mt_consume_retry_total Total number of message consume retries
mt_consume_duration_seconds Elapsed time spent consuming a message, in seconds
mt_delivery_duration_seconds Elapsed time between when the message was sent and when it was consumed, in seconds.
mt_publish_total Total number of messages published
mt_publish_fault_total Total number of message publish faults
mt_send_total Total number of messages sent
mt_send_fault_total Total number of message send faults
mt_bus Number of bus instances
mt_endpoint Number of receive endpoint instances
mt_consumer_in_progress Number of consumers in progress
mt_handler_in_progress Number of handlers in progress
mt_saga_in_progress Number of sagas in progress
mt_activity_execute_in_progress Number of activity executions in progress
mt_activity_compensate_in_progress Number of activity compensations in progress
mt_activity_execute_total Total number of activities executed
mt_activity_execute_fault_total Total number of activity executions faults
mt_activity_execute_duration_seconds Elapsed time spent executing an activity, in seconds
mt_activity_compensate_total Total number of activities compensated
mt_activity_compensate_failure_total Total number of activity compensation failures
mt_activity_compensate_duration_seconds Elapsed time spent compensating an activity, in seconds

# Labels

For the metrics above, labels are specified where appropriate.

Name Description
service_name The service name specified at bus configuration
endpoint_address The endpoint address
message_type The message type for the metric
consumer_type The consumer, saga, or activity type for the metric
activity_name The activity name
argument_type The activity execute argument type
log_type The activity compensate log type
exception_type The exception type for a fault metric