Cannot parse DSC from envelope

[Dav1dde]

Relay fails to parse the DSC with the debug message failed to parse sampling context error=invalid type: floating point 1, expected a string.

relay-1                                         | 2024-10-02T08:04:02.957498Z DEBUG relay_server::envelope: failed to parse sampling context error=invalid type: floating point `1`, expected a string

Originally seen here: getsentry/self-hosted#3312 (comment)

It looks like Relay expects the sample rate to be a string, we can be a bit more lenient if that is the issue:

relay/relay-sampling/src/dsc.rs

Lines 152 to 154 in 9f45b02

	let value = match Option::<Cow<'_, str>>::deserialize(deserializer)? {
	Some(value) => value,
	None => return Ok(None),

COS:

• Verify with the mentioned/used SDK
• Fix the issue

Note: This error does not cause dropped events and for self hosted is without consequences.

[jan-auer]

This is expected. As per spec, the sample rate must be sent as a string, this is a buggy SDK:
https://develop.sentry.dev/sdk/telemetry/traces/dynamic-sampling-context/#dsc-specification

Consequence of this is that distributed DS and extrapolation will not work, the data will be stored, however.

[Dav1dde]

@jan-auer Should we be a bit more lenient here and accept both (string and numerical) or just close this?

[Dav1dde]

Created an issue in the Python SDK, but I think we should just be more lenient in Relay to have a working DSC for all clients using an older SDK version.

[antonpirker]

This is a problem in the Python SDK. The sample_rate in the envelope headers of an error is indeed a float instead of a str. (for envelopes containing transactions it is correct.)

We have fix and will probably release it next week: getsentry/sentry-python#3603