ApplicationInsights-dotnet VS opentelemetry-dotnet

Since April 22, 2021, you can use the new TelemetryClient.FlushAsync() task-based API with a custom IHostedService to ensure that you don't lose any telemetry data:

Severity Code Description Project File Line Suppression State Priority Warning CS0618 'TelemetryConfiguration.InstrumentationKey.set' is obsolete: 'InstrumentationKey based global ingestion is being deprecated. Use TelemetryConfiguration.ConnectionString. See https://github.com/microsoft/ApplicationInsights-dotnet/issues/2560 for more details.' disyanonymizer C:\Path 33 Active Normal

Why not Application Insights?

ApplicationInsights-dotnet/DocumentDbHttpParser.cs at main · microsoft/ApplicationInsights-dotnet · GitHub

open-telemetry/opentelemetry-dotnet: The OpenTelemetry .NET Client (github.com)

💡Good to know -- If you wish to export traces to Jaeger, you should use the AddJaegerExporter instead of the AddOtlpExporter. Visit the opentelemetry-dotnet repository to see how it's done.

We're going to use OpenTelemetry .NET SDK. Add following nuget dependencies to the project:

We instrument the application with the OpenTelemetry SDK and SqlClient instrumentation library for .NET. First, we add the following NuGet package references to the API’s project file:

It should be handled automatically by OpenTelemetry middlewares. Just look through documentation and samples https://github.com/open-telemetry/opentelemetry-dotnet

Besides that, the propagation fields (traceparent and tracestate) were added in the message header. In the last article, I said that the standard (in the Working Draft (WD) step of the w3c process) recommends to add the propagation fields in the application-properties section by the message publisher. For the current example, I chose to propagate that context in the message header even for AMQP calls as was done in the dotnet OpenTelemetry example. It's important to reinforce that Trace Context: AMQP protocol is not a W3C Recommendation yet. Take a look at the place where the propagation fields were added:

As long as the Azure Functions app knows the instrumentation key from an Application Insights instance, it traces almost everything. OpenTelemetry.NET is one of the Open Telemetry implementations, has recently released v1.0 for tracing. Both metrics and logging are close to GA. However, it doesn't work well with Azure Functions. Therefore, in this post, let's manually implement the tracing at the log level, which is sent to Application Insights.