Sampling parameters require a Context with an embedded Span

[MrAlias]

Currently we use the following sampling decision parameteres:

opentelemetry-go/sdk/trace/sampling.go

Lines 31 to 40 in 90bd4ab

	// SamplingParameters contains the values passed to a Sampler.
	type SamplingParameters struct {
	ParentContext trace.SpanContext
	TraceID trace.TraceID
	Name string
	HasRemoteParent bool
	Kind trace.SpanKind
	Attributes []attribute.KeyValue
	Links []trace.Link
	}

The specification requires:

• Context with parent Span.
  The Span's SpanContext may be invalid to indicate a root span.
  ...

This likely needs to be addressed more holistically here first.

[Aneurysm9]

I think this also ties in to the concept of a "propagation span" that only has a span context and is non-recording. I think with the IsRemote predicate on span contexts we're now closer to being able to simply stick a span into a context with only a remote span context and let the SDK figure out what to do with it when starting a new span.

[MrAlias]

I think this also ties in to the concept of a "propagation span" that only has a span context and is non-recording. I think with the IsRemote predicate on span contexts we're now closer to being able to simply stick a span into a context with only a remote span context and let the SDK figure out what to do with it when starting a new span.

Agreed! That is a change I am working on submitting here (which will resolve "Reconsider the context keys"). It requires this to merge first, but I think we can achieve this now.