Rule proposal: Traces contain multiple spans

[svrnm]

Proposal

Rule ID: SPA-00x

Description: Traces contain more than one span

Rationale: While it is possible that a trace only has one span, the majority of traces should have some spans (2++) to be able to fully leverage the possibilities that distributed tracing provides.

Target: Span

Criteria: Trace has more than one span

Impact: Low

[jpkrohling]

I like that. I'm wondering if we should have experimental rules, as we might want to give this one a try in the real-world before committing to it.

[svrnm]

I like that. I'm wondering if we should have experimental rules, as we might want to give this one a try in the real-world before committing to it.

Agreed. Indeed there are situations where you only have one span in a trace and it's still valuable, e.g. when the first span already represents an error/exception and no more code was executed (and with that no span), but often it's a sign of either spans being disconnected or a lot of traces being generated for trivial endpoints, which the user might want to sample.

Maybe there's an extended rule of that where you try to catpure the average/median amount of spans per trace and provide some guidance for good numbers (probably above 1, maybe above 3, and below #n), which would indeed require some experiemnts

[mmanciop]

I don't think this is generally a good rule: spans readiness and liveness checks are valuable spans, especially when they fail. I actually often say to Dash0 customers about using Spam Filters to throw away the successful spans resulting from probes, and keep the failed ones.

[svrnm]

I don't think this is generally a good rule: spans readiness and liveness checks are valuable spans, especially when they fail. I actually often say to Dash0 customers about using Spam Filters to throw away the successful spans resulting from probes, and keep the failed ones.

I agree, that's why my proposal says that "the majority of traces". I am not sure how much the instrumentation score specification allows such a level of ambiguity or can make a judgment across lots of traces.