feat(provider): expose context provider in ddtrace.trace (#12135)

ddtrace v3.0 is set to remove `ddtrace.providers` module from the public
API. However we should still allow users to use their own
ContextProviders. This PR ensures the BaseContextProvider remains in the
public API and can be used in `tracer.configure(...)`.

## Checklist
- [x] PR author has checked that all the criteria below are met
- The PR description includes an overview of the change
- The PR description articulates the motivation for the change
- The change includes tests OR the PR description describes a testing
strategy
- The PR description notes risks associated with the change, if any
- Newly-added code is easy to change
- The change follows the [library release note
guidelines](https://ddtrace.readthedocs.io/en/stable/releasenotes.html)
- The change includes or references documentation updates if necessary
- Backport labels are set (if
[applicable](https://ddtrace.readthedocs.io/en/latest/contributing.html#backporting))

## Reviewer Checklist
- [x] Reviewer has checked that all the criteria below are met 
- Title is accurate
- All changes are related to the pull request's stated goal
- Avoids breaking
[API](https://ddtrace.readthedocs.io/en/stable/versioning.html#interfaces)
changes
- Testing strategy adequately addresses listed risks
- Newly-added code is easy to change
- Release note makes sense to a user of the library
- If necessary, author has acknowledged and discussed the performance
implications of this PR as reported in the benchmarks PR comment
- Backport labels are set in a manner that is consistent with the
[release branch maintenance
policy](https://ddtrace.readthedocs.io/en/latest/contributing.html#backporting)

.github/CODEOWNERS

@@ -166,12 +166,14 @@ ddtrace/internal/remoteconfig       @DataDog/remote-config @DataDog/apm-core-pyt
 tests/internal/remoteconfig         @DataDog/remote-config @DataDog/apm-core-python
 
 # API SDK
+ddtrace/trace/                                    @DataDog/apm-sdk-api-python
 ddtrace/_trace/                                    @DataDog/apm-sdk-api-python
 ddtrace/opentelemetry/                             @DataDog/apm-sdk-api-python
 ddtrace/internal/opentelemetry                     @DataDog/apm-sdk-api-python
 ddtrace/opentracer/                                @DataDog/apm-sdk-api-python
 ddtrace/propagation/                               @DataDog/apm-sdk-api-python
 ddtrace/filters.py                                 @DataDog/apm-sdk-api-python
+ddtrace/provider.py                                @DataDog/apm-sdk-api-python
 ddtrace/pin.py                                     @DataDog/apm-sdk-api-python
 ddtrace/sampler.py                                 @DataDog/apm-sdk-api-python
 ddtrace/sampling_rule.py                           @DataDog/apm-sdk-api-python

ddtrace/provider.py

@@ -7,7 +7,8 @@
 
 
 deprecate(
-    "The context provider interface is deprecated.",
-    message="The trace context is an internal interface and will no longer be supported.",
+    "The context provider interface is deprecated",
+    message="Import BaseContextProvider from `ddtrace.trace` instead.",
     category=DDTraceDeprecationWarning,
+    removal_version="3.0.0",
 )

ddtrace/trace/__init__.py

@@ -1,6 +1,7 @@
 from ddtrace._trace.context import Context
 from ddtrace._trace.filters import TraceFilter
 from ddtrace._trace.pin import Pin
+from ddtrace._trace.provider import BaseContextProvider
 from ddtrace._trace.span import Span
 from ddtrace._trace.tracer import Tracer
 
@@ -15,4 +16,5 @@
     "Tracer",
     "Span",
     "tracer",
+    "BaseContextProvider",
 ]

docs/advanced_usage.rst

@@ -221,7 +221,7 @@ context management.
 
 If there is a case where the default is insufficient then a custom context
 provider can be used. It must implement the
-:class:`ddtrace.provider.BaseContextProvider` interface and can be configured
+:class:`ddtrace.trace.BaseContextProvider` interface and can be configured
 with::
 
     tracer.configure(context_provider=MyContextProvider)

releasenotes/notes/feat-expose-base-context-provider-530ebec2225f6c8d.yaml

@@ -0,0 +1,5 @@
+---
+deprecations:
+  - |
+    tracing: Moves ``ddtrace.provider.BaseContextProvider`` to ``ddtrace.trace.BaseContextProvider``. 
+    The ``ddtrace.provider`` module is deprecated and will be removed in v3.0.0.