Missing Sampled Flag in Trace Headers

[kpujjigit]

Is there an existing issue for this?

• I have checked for existing issues https://github.com/getsentry/sentry-javascript/issues
• I have reviewed the documentation https://docs.sentry.io/
• I am using the latest SDK release https://github.com/getsentry/sentry-javascript/releases

How do you use Sentry?

Sentry Saas (sentry.io)

Which SDK are you using?

@sentry/vue

SDK Version

7.99.0

Framework Version

No response

Link to Sentry event

No response

SDK Setup

No response

Steps to Reproduce

Events sent into Sentry as part of typical ingestion.

Expected Result

traces-sampled flag ("-1" appended to the traceID) expected. Expected per SDK test-case

Actual Result

Sentry shows "Unknown" for Sampled Status under Issue Context
No traces-sampled flag appended to traceID.

[s1gr1d]

The sampled flag changes based on tracesSampleRate in Sentry.init. When the sampling decision is positive (like when setting tracesSampleRate: 1) the sampled flag in the trace header should always be 1, as every request will be sampled.

When the sampling decision is negative, the sampled flag will be 0 (like when setting tracesSampleRate: 0.3 and the request is one of the 70% of requests which are not sampled).

When there is no flag, it simply means that there is no sampling decision (yet). It might make sense to document this better if you think this is not clear. What do you think?

See more here in the develop docs.

Do you have a reproducible use-case where the sampled flag is not set correctly?

[AbhiPrasad]

In tracing without performance for v7, we omit the sampled flag. Having the sampled flag is optional, if it does not exist it can be treated as -0. I followed up in slack about this issue, closing here.