Tracing doesn't work

[bboreham]

It relies on tracerKey which is only used in one place to read from a Context. Since it is never set, the NoopTracer is used.

objstore/tracing/tracing.go

Lines 33 to 38 in 79dcec7

	func tracerFromContext(ctx context.Context) opentracing.Tracer {
	val := ctx.Value(tracerKey)
	if sp, ok := val.(opentracing.Tracer); ok {
	return sp
	}
	return nil

In the similar package in thanos-io/thanos there is a function to set the key:

https://github.com/thanos-io/thanos/blob/25d91c103a416df733320563bb108d734f91b8af/pkg/tracing/tracing.go#L37-L39

Note that the tracerKey there is a different value.