Parent.id is set to a non-Elastic APM Span/Transaction

Found in Opbeans and also here.

One example of such an id: |eb88cbba-4040e4007bc3c335..

My quick slack analysis:

that id looks like an id coming from Activity https://docs.microsoft.com/en-us/dotnet/api/system.diagnostics.activity?view=netcore-3.1
Activity is a “tracing library” build into .NET (fun fact the C# OpenTelemetry SIG decided  to take this API and turn it into an  OpenTelemetry compatible API - so think it’s like a span) -  anyways, so what we do in the agent is that we try to keep our trace id in sync with  the traceid on Activity (that way if users look at Activity.Current.TraceId then it’ll be the same as our trace id in elastic). Problem is Activity pre-dates W3C TraceContext and - originally it had a hierarchical id format (that’s what you pasted), but now it also supports w3c format. We only keep the id in sync when  it’s w3c format: https://github.com/elastic/apm-agent-dotnet/blob/master/src/Elastic.Apm/Model/Transaction.cs#L85
At least that’s my intention. I can see 2 options here: Either I messed up and somewhere a check is missing or it’s in W3C format, but it’s parent is not, so the check is ok, but still we set the parent id which is in the old format - not sure it’s possible.
I’ll dig deeper - I still just start my day here. But thanks for mentioning this! that id looks like an id coming from Activity https://docs.microsoft.com/en-us/dotnet/api/system.diagnostics.activity?view=netcore-3.1
Activity is a “tracing library” build into .NET (fun fact the C# OpenTelemetry SIG decided  to take this API and turn it into an  OpenTelemetry compatible API - so think it’s like a span) -  anyways, so what we do in the agent is that we try to keep our trace id in sync with  the traceid on Activity (that way if users look at Activity.Current.TraceId then it’ll be the same as our trace id in elastic). Problem is Activity pre-dates W3C TraceContext and - originally it had a hierarchical id format (that’s what you pasted), but now it also supports w3c format. We only keep the id in sync when  it’s w3c format: https://github.com/elastic/apm-agent-dotnet/blob/master/src/Elastic.Apm/Model/Transaction.cs#L85
At least that’s my intention. I can see 2 options here: Either I messed up and somewhere a check is missing or it’s in W3C format, but it’s parent is not, so the check is ok, but still we set the parent id which is in the old format - not sure it’s possible.
I’ll dig deeper - I still just start my day here. But thanks for mentioning this! ```

[gregkalapos]

Hi @arindamdat, yes it is. It was released in version 1.6.0.

[gregkalapos]

Thanks @arindamdat! That scenario is also reproducible - in that case, already in ServiceA we have an issue, which is that we set the ParentId of the transaction in ServiceA to the activity parent id which was created by ASP.NET Core - and that is why there won’t by any transaction there where the ParentId is null. And a trace must begin with a transaction where the ParentId is null, so that is why you don’t see traces.

The PR I just opened also covers that issue.