Adding correlation id to automatically generated telemetry with App Insights

Question

I'm very new to Application Insights, and I'm thinking of using it for a set of services I plan on implementing with asp.net webapi. I was able to get the basic telemetry up and running very easily (right-clicking on a project on VS, Add Application Insights), but then I hit a block. I plan to have a correlation id set in the request headers for calls to downstream services, and I would like to tag all the telemetry related to one outside call with the same correlation id.

So far I've found that there is a way to configure a TelemetryInitializer, but if I understood correctly, this is run before I get to access the request, meaning I can't check if there is a correlation id that I should attach.

So I guess there might be 2 ways to solve this: 1) if I can somehow actually get access to the request headers before the initializer, that would obviously solver the problem, or 2) somehow get a hold of the TelemetryClient instance that is used to report the automatically generated telemetry.

Perhaps the last resort would be to turn off all of the automatic stuff and do all of it manually, when I could of course control what properties are set on the TelemetryClient. But this would be quite a lot more work, so I'd prefer to find some other solution.

Answer 1

You were rights saying that you should use TelemetryInitializer. All TelemetryInitializers are called when Track method is called on any telemetry item. Autogenerated request telemetry is "tracked" on request OnEnd, you should have all your custom headers available for you at that time.

Answer 2

Please also have a look at OperationId - this is part of the standard context managed by App Inisghts and is used exactly for the purpose of correlating requests with downstream execution. This is created and passed automatically, including traces (if you use trackTrace).

Moreover, we have built-in support in our UX for easily seeing all telemetry for a particular operation - it can be found in "Search->Details-->Related Items-->All telemetry for this operation"