# Monitoring NServiceBus endpoints with Application Insights

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[Azure Application Insights](https://learn.microsoft.com/en-us/azure/azure-monitor/app/app-insights-overview) (App Insights) provides monitoring and alerting capabilities that can be leveraged to monitor the health of NServiceBus endpoints.

This sample shows how to capture NServiceBus OpenTelemetry traces and export them to App Insights. The sample simulates message load as well as a 10% failure rate on processing messages.

## Prerequisites

This sample requires an App Insights connection string.

> [!NOTE]
> Although the sample uses Azure Application Insights, the solution itself does not require an Azure message transport. This example uses the [Learning Transport](/transports/learning/index.md) but could be modified to run on any [transport](/transports/index.md).

## Running the sample

1. Create an Application Insights resource in Azure
2. Copy the connection string from the Azure portal dashboard into the sample
3. Start the sample endpoint
4. Press any key to send a message, or <kbd>ESC</kbd> to quit

### Reviewing traces

1. In the Azure portal Application Insights resource you just created, open the _Investigate_ → _Performance_ panel
2. Drill into the samples
3. Review the custom properties

![Timeline view of a trace in Application Insights](trace-timeline.png)

### Reviewing metrics

Navigate to _Monitoring_ → _Metrics_ on the Azure portal dashboard for the configured Application Insights instance to start creating graphs.

> [!NOTE]
> It may take a few minutes for the metrics data to populate to Azure. Metrics will only appear on the dashboard once they have reported at least one value.

#### Message processing counters

To monitor the rate of messages being fetched from the queuing system, processed successfully, retried, and failed for the endpoint, use the following metrics:

- `nservicebus.messaging.fetches`
- `nservicebus.messaging.successes`
- `nservicebus.messaging.failures`

![Graph showing fetched, success, and failed counters in Application Insights](metrics-counters.png)

#### Recoverability

To monitor [recoverability](/nservicebus/recoverability/index.md) metrics use:

- `nservicebus.recoverability.immediate`
- `nservicebus.recoverability.delayed`
- `nservicebus.recoverability.error`

![Graph showing recoverability metrics in Application Insights](metrics-recoverability.png)

#### Handler time, critical time, and processing time

To monitor [handler time, processing time, and critical time](/monitoring/metrics/definitions.md#metrics-captured) (in seconds) for successfully processed messages, use:

- `nservicebus.messaging.handler_time`
- `nservicebus.messaging.processing_time`
- `nservicebus.messaging.critical_time`

![Graph showing processing time and critical time metrics in Application Insights](metrics-timing.png)

## Code walk-through

In versions of NServiceBus lower than 10.0, OpenTelemetry has to be manually enabled:

<!-- snippet: enable-open-telemetry -->

```cs
var endpointConfiguration = new EndpointConfiguration(endpointName);
endpointConfiguration.EnableOpenTelemetry();
```

<!-- endsnippet -->

### Tracing

The endpoint configures an OpenTelemetry trace provider that includes the `NServiceBus.Core` source and exports collected traces to Azure Monitor.

<!-- snippet: enable-tracing -->

```cs
var traceProvider = Sdk.CreateTracerProviderBuilder()
    .SetResourceBuilder(resourceBuilder)
    .AddSource("NServiceBus.Core*")
    .AddAzureMonitorTraceExporter(o => o.ConnectionString = appInsightsConnectionString)
    .AddConsoleExporter()
    .Build();
```

<!-- endsnippet -->

### Meters

The endpoint configures an OpenTelemetry meter provider that includes the `NServiceBus.Core` meter and exports metric data to Azure Monitor.

<!-- snippet: enable-meters -->

```cs
var meterProvider = Sdk.CreateMeterProviderBuilder()
    .SetResourceBuilder(resourceBuilder)
    .AddMeter("NServiceBus.Core*")
    .AddAzureMonitorMetricExporter(o => o.ConnectionString = appInsightsConnectionString)
    .AddConsoleExporter()
    .Build();
```

<!-- endsnippet -->