4.0.0 release

[carlosalberto]

This issue was created to track and discuss the eventual 4.0.0 release.

This version will include Span propagation through ScopeManager, pointing the to 2.0.0rc1 and 3.0.0rc1 versions of opentracing and basictracer, respectively.

Current status

• The current effort lives in the carlos/ot-upgrade-2.0 branch.
• The lightstep tracer takes an optional scope_manager argument, falling back to a thread-local one (provided by basictracer).
• Examples have been ported to handle Python 3.4, and a Changelog draft will be added (@katiabazzi)

Questions

• Should we do a Release Candidates? For OT it makes perfect sense as many different vendors may want to try the API out in their own codebases, and validate it. For the Lightstep tracer, we may instead decide to keep the effort in a branch for now, and release when the final OT packages are ready. Else, do RC iterations as opentracing and basictracer do.
• It looks the officially supported Python versions are 2.7 and 3.4. My impression is that we should stick to those ones, and, whenever we want to support 3.6 (probably after the 4.0.0 release), do another iteration for it.
• Should we create maybe a v4.0.0 branch to hold the next release, instead of having the changes in carlos/ot-upgrade-2.0?

@katiabazzi @frenchfrywpepper @tedsuo

[tedsuo]

An implementation of OpenTracing v2.0-RC1 can now be found on the v4.0.0 branch: https://github.com/lightstep/lightstep-tracer-python/tree/v4.0.0

[tedsuo]

Now that OpenTracing-python v2.0 has been released, the The v4.0 branch of the LightStep python tracer has been updated to reflect the final changes:

https://github.com/lightstep/lightstep-tracer-python/tree/v4.0.0

[carlosalberto]

Closing this issue as we already did the 4.0 release (along the OT 2.0 bits).