Baggage is not propagated by OpenTracing bridge

[bboreham]

Description

When using BridgeTracer, after Inject the Carrier has no entries for baggage.
After Extract the resulting SpanContext has nil in the baggage field.

Environment

• OS: Linux
• Architecture: ARM64 (M1)
• Go Version: go1.17.1 darwin/arm64
• opentelemetry-go version: 1884de2, shortly after v1.6.3

Steps To Reproduce

Starting with the test from #2141, add some baggage:
bboreham@c162bdd

Observe the test now fails:

go test -run ^TestHeaderCarrier$ go.opentelemetry.io/otel/bridge/opentracing
--- FAIL: TestHeaderCarrier (0.00s)
    /Users/bryan/src/github.com/open-telemetry/opentelemetry-go/bridge/opentracing/bridge_test.go:93: Extracted span context does not match: 
&opentracing.bridgeSpanContext{bag:baggage.Baggage{list:baggage.List{"Foo":baggage.Item{Value:"bar", Properties:[]baggage.Property(nil)}}}, otelSpanContext:trace.SpanContext{traceID:trace.TraceID{0x5e, 0xb4, 0x86, 0x1, 0x52, 0xcc, 0x3b, 0x6a, 0xab, 0xdd, 0x71, 0x2f, 0xe7, 0x5a, 0x7d, 0x54}, spanID:trace.SpanID{0x41, 0x3f, 0xec, 0x7c, 0x4b, 0xec, 0xea, 0x13}, traceFlags:0x0, traceState:trace.TraceState{list:[]trace.member(nil)}, remote:false}}, 
&opentracing.bridgeSpanContext{bag:baggage.Baggage{list:baggage.List(nil)}, otelSpanContext:trace.SpanContext{traceID:trace.TraceID{0x5e, 0xb4, 0x86, 0x1, 0x52, 0xcc, 0x3b, 0x6a, 0xab, 0xdd, 0x71, 0x2f, 0xe7, 0x5a, 0x7d, 0x54}, spanID:trace.SpanID{0x41, 0x3f, 0xec, 0x7c, 0x4b, 0xec, 0xea, 0x13}, traceFlags:0x0, traceState:trace.TraceState{list:[]trace.member(nil)}, remote:true}}

Expected behavior

Baggage should be propagated.

Commentary

There are lines in BridgeTracer.Inject and Extract aimed at doing something with baggage:

opentelemetry-go/bridge/opentracing/bridge.go

Line 648 in 1884de2

ctx = baggage.ContextWithBaggage(ctx, bridgeSC.bag)

opentelemetry-go/bridge/opentracing/bridge.go

Line 667 in 1884de2

baggage := baggage.FromContext(ctx)

However the propagator Inject and Extract methods do not seem to line up with this code's expectations.

[anshul35]

Hi ,

Can I take this bug ?

[shubham-bansal96]

@MrAlias @MadVikingGod
I would like to work on this. Could you please provide me any entry point from where I can start ?

[shubham-bansal96]

@bboreham
I am not able to reproduce this issue, could you please provide me few more details regarding replicating steps ?

[bboreham]

You tried the test at the commit I linked?

[shubham-bansal96]

Thanks @bboreham , Now i am able to reproduce this.

[scorpionknifes]

The following fixes the example given in bboreham@c162bdd

- otel.SetTextMapPropagator(propagation.TraceContext{})
+ otel.SetTextMapPropagator(propagation.NewCompositeTextMapPropagator(propagation.TraceContext{}, propagation.Baggage{}))

This is expected behaviour, I've written a test in #4776 to cover this.

No changes needed, happy to close this

[pellared]

@bboreham Can you please check #2793 (comment)?

[bboreham]

Thanks, TIL.

I do think this could be better documented; I did a search of a hundred or so repos I work with and think they were about 70/30 whether they added baggage or not.