Feature: github.com/streadway/amqp tracing

[axw]

Implement tracing for https://github.com/streadway/amqp.

This will probably have to be a collection of amqp.Channel method wrappers that:

• add context.Context
• create spans using said context
• add headers (when we support distributed tracing)
• call through to the underlying amqp.Channel

[ekrucio]

Is this issue still open? This missing feature is a deal-breaker for our migration to Elastic APM.
If it's open and noone is working on it, I would like to implement it.
@axw @graphaelli

[axw]

@ekrucio nobody else is working on it. I see you have opened a PR, thank you - I'll take a look shortly.