How to set the trace ID (operation ID) based on HTTP header?

[nlykkei]

Package

OpenTelemetry

Is your feature request related to a problem?

I want to set the trace ID (operation ID) of a request to an ASP.NET Core application based on a custom HTTP header (correlation-id).

According to the docs, this should be possible using ITelemetryProcessor in the Application Insights SDK:

https://learn.microsoft.com/en-us/azure/azure-monitor/app/api-filtering-sampling?tabs=dotnet%2Cjavascriptwebsdkloaderscript

I'm looking for similar functionality for the Azure.Monitor.OpenTelemetry.AspNetCore package.

All of our upstream services are currently using our custom correlation-id header, so I would like to use this header for the operation ID instead of rewriting each of those client applications to use traceparent OTEL header:

https://learn.microsoft.com/en-us/azure/azure-monitor/app/distributed-trace-data#correlation-headers-using-w3c-tracecontext

How can I set the operation ID for the incoming request based on the value of a custom HTTP header?

What is the expected behavior?

I would like to set the operation ID to the value of a custom HTTP header, instead of having ASP.NET Core generate a random GUID

Which alternative solutions or features have you considered?

I can't find any solutions or workarounds

Additional context

No response

[cijothomas]

It is possible to achieve this via https://learn.microsoft.com/en-us/dotnet/api/system.diagnostics.distributedcontextpropagator?view=net-9.0 .Asp.Net Core uses the default propagator, which uses W3CTraceContext format and looks for trace parent header to obtain traceid. One can override the default propagator so that trace-id can be obtained from any other place like a diff. header etc.

But this is not very well documented from what I can tell.
Also there is OTel specific propagator, and they don't really interop well with the one from .NET runtime.

[nlykkei]

@cijothomas Thank you very much for your comment.

Could I ask you for a minimal example of how to achieve this? Should I just subclass the DistributedContextPropagator base class, and set it as the DistributedContextPropagator.Current property in startup (Program.cs)?

I want the following behaviour:

If correlation-id HTTP header is available, then use it for the operation ID (the parent ID will be initialised randomly). If it's not available, then use the default behaviour (WC3TraceContext traceparent)

Also there is OTel specific propagator, and they don't really interop well with the one from .NET runtime.

Isn't the default propagater, which is WC3TraceContext-compliant also OTEL-specific?

[cijothomas]

Unfortunately, I don't have the bandwidth to prepare a minimal example. There are no docs either, so it'll going to take some efforts to manually stitch these pieces. It is not sufficient to just fix DistributedContextPropagator, as InstrumentationLibrary from the contrib repo for Asp.Net Core uses a different ContextPropagator, and they are not aware of each other.

I couldn't find the tracking issue to fix this issue othan than #3028 which is just about docs.

Also there is OTel specific propagator, and they don't really interop well with the one from .NET runtime.
Isn't the default propagater, which is WC3TraceContext-compliant also OTEL-specific?

Not sure I follow. Since you are in need of overriding W3CTraceContext to something else, then the defaults don't work in your favor anymore. i.e you want to use correlation-id to get TraceId. But OTel looks for it in a different place. Runtime's Propagator that is used by Asp.Net Core looks for it a different place. So you need to change both likely...

(Sorry for the sad state of propagator docs(lack of docs)...)

[cijothomas]

#3769 Found this one, which might give some hints. (Note its unfinished work, might not be fully ready to be consumed as-is)