How to properly do context propagation (http & grpc)?

[moorara]

With http and grpc examples removed (and related instrumentation packages) in v0.11.0, I see three options for injecting and extracting correlation contexts:

• api/trace: using Inject and Extract methods available on B3 (which B3Encoding should be used?)
• api/correlation: using Inject and Extract methods available on CorrelationContext
• api/propagation: using InjectHTTP and ExtractHTTP methods.

How are these three approaches different and which one is recommended?

[MrAlias]

The examples and instrumentation have been moved BTW:

• https://github.com/open-telemetry/opentelemetry-go-contrib/tree/master/instrumentation/net/http
• https://github.com/open-telemetry/opentelemetry-go-contrib/tree/master/instrumentation/net/http/example
• https://github.com/open-telemetry/opentelemetry-go-contrib/tree/master/instrumentation/net/http/httptrace
• https://github.com/open-telemetry/opentelemetry-go-contrib/tree/master/instrumentation/net/http/httptrace/example
• https://github.com/open-telemetry/opentelemetry-go-contrib/tree/master/instrumentation/google.golang.org/grpc
• https://github.com/open-telemetry/opentelemetry-go-contrib/tree/master/instrumentation/google.golang.org/grpc/example

To answer the question directly though, nothing has changed an you would still use propagation.ExtractHTTP and propagation.InjectHTTP with the configured or global propagators.

These will likely change names in an upcoming release as they have been renamed at the specification level.