A few months ago, I blogged about integrating Application Insights in HotChocolate to monitor the executed GraphQL queries and mutations. In HotChocolate 11, the diagnostics system has been rewritten and the code I shared in that post no longer works. Here is finally the updated post I promised on how to achieve this in HotChocolate 11.
Creating our own DiagnosticEventListener
- Starting from HotChocolate 11, your diagnostic class should inherit from DiagnosticEventListener. We still inject the Application Insights TelemetryClient in the constructor:
Remark: There seems to be a problem with dependency injection in HotChocolate 11. This problem was fixed in HotChocolate 12. I show you a workaround at the end of this article.
- In this class you need to override at least the ExecuteRequest method:
- To track the full lifetime of a request, we need to implement a class that implements the IActivityScope interface. In the constructor of this class, we put all our initialization logic:
- I'm using 2 small helper methods GetHttpContextFrom and GetOperationIdFrom:
- In the Dispose() method, we clean up all resources and send the telemetry data to Application Insights for this request:
- Here we are using 1 extra helper method HandleErrors:
Here is the full code:
Configuring the DiagnosticEventListener
Before we can use this listener, we need to register it in our Startup.cs file:
Remark:Notice that we are using an overload of the AddDiagnosticEventListener method to resolve and pass the TelemetryClient instance to the listener. If you don’t use this overload, nothing gets injected and you end up with an error. As mentioned, this code only works starting from HotChocolate 12. For Hot Chocolate 11, check out the workaround below.
Workaround for HotChocolate 11
In HotChocolate 11, when you try to use the ServiceProvider instance inside the listener, you don’t get access to the application level services. This means that you cannot resolve the TelemetryClient. As a hack we can build an intermediate ServiceProvider instance and use that instead: