Open Telemetry Export for Event Hubs

A library for sending OTLP data to an Azure Event Hubs endpoint.

What's it for?

This library is specifically to simplify in process scenarios where agents or other collector patterns aren't an option and you'd like the process being instrumented to be responsible for transmitting data to the target

How does it work?

This is a bit of syntantic sugar to help with bootstrapping the Event Hubs endpoint and setting up authentication. The exporter option we expose here AddOtlpEventHubExporter builds directly onto AddOtlpExporter and sets up the necessary configuration.

In particular, that's setting the protocol to HttpProtobuf and the HttpClientFactory to take an instance that handles tokens and token refreshes.

The library will support either SAS key authentication or Managed Identity, and sets up the HttpClient to transmit the appropriate authorization header.

Example configurations

Create an EventHubOptions object and choose from either SAS key authentication or managed identity. When configuring your services, you now have an extension named AddOtlpEventHubExporter that you can pass the options to

var eventHubOptions = new EventHubOptions
{
    AuthenticationMode = AuthenticationMode.SasKey,
    KeyName = "the-name-of-the-access-key"    
    AccessKey = "the-event-hub-access-key",
    EventHubFqdn = "fully-qualified-target-eventhub-uri"
};

OR

var eventHubOptions = new EventHubOptions
{
    AuthenticationMode = AuthenticationMode.ManagedIdentity,
    EventHubFqdn = "fully-qualified-target-eventhub-uri"
};

services.AddOpenTelemetryMetrics(builder => builder
    .SetResourceBuilder(ResourceBuilder.CreateDefault().AddService("DemoService"))
    .AddAspNetCoreInstrumentation()
    .AddMeter("MeterName")
    .AddOtlpEventHubExporter(eventHubOptions));

Permissions

When running as a SAS key, the permissions are available from the access key you've used. However, when running in ManagedIdentity, you'll need to grant the Azure Event Hubs Data Sender role to the identity you want to access the Event Hub endpoint.