Reverted documentation of custom sampler feature while circular dependency bug is explored

CHANGELOG.md

@@ -7,6 +7,8 @@ and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0
 
 ## Unreleased
 
+- Removed documentation of custom sampler feature while circular dependency bug is explored
+  ([#3014](https://github.com/open-telemetry/opentelemetry-python/pull/3014))
 - Add logarithm and exponent mappings
   ([#2960](https://github.com/open-telemetry/opentelemetry-python/pull/2960))
 - Add and use missing metrics environment variables

opentelemetry-sdk/src/opentelemetry/sdk/trace/sampling.py

@@ -64,7 +64,7 @@
         ...
 
 The tracer sampler can also be configured via environment variables ``OTEL_TRACES_SAMPLER`` and ``OTEL_TRACES_SAMPLER_ARG`` (only if applicable).
-The list of built-in values for ``OTEL_TRACES_SAMPLER`` are:
+The list of known values for ``OTEL_TRACES_SAMPLER`` are:
 
     * always_on - Sampler that always samples spans, regardless of the parent span's sampling decision.
     * always_off - Sampler that never samples spans, regardless of the parent span's sampling decision.
@@ -73,7 +73,7 @@
     * parentbased_always_off - Sampler that respects its parent span's sampling decision, but otherwise never samples.
     * parentbased_traceidratio - Sampler that respects its parent span's sampling decision, but otherwise samples probabalistically based on rate.
 
-Sampling probability can be set with ``OTEL_TRACES_SAMPLER_ARG`` if the sampler is traceidratio or parentbased_traceidratio. Rate must be in the range [0.0,1.0]. When not provided rate will be set to 1.0 (maximum rate possible).
+Sampling probability can be set with ``OTEL_TRACES_SAMPLER_ARG`` if the sampler is traceidratio or parentbased_traceidratio, when not provided rate will be set to 1.0 (maximum rate possible).
 
 Prev example but with environment variables. Please make sure to set the env ``OTEL_TRACES_SAMPLER=traceidratio`` and ``OTEL_TRACES_SAMPLER_ARG=0.001``.
 
@@ -96,38 +96,6 @@
     # created spans will now be sampled by the TraceIdRatioBased sampler with rate 1/1000.
     with trace.get_tracer(__name__).start_as_current_span("Test Span"):
         ...
-
-In order to create a configurable custom sampler, create an entry point for the custom sampler factory method under the entry point group, ``opentelemetry_traces_sampler``. The custom sampler factory
-method must be of type ``Callable[[str], Sampler]``, taking a single string argument and returning a Sampler object. The single input will come from the string value of the
-``OTEL_TRACES_SAMPLER_ARG`` environment variable. If ``OTEL_TRACES_SAMPLER_ARG`` is not configured, the input will be an empty string. For example:
-
-.. code:: python
-
-    setup(
-        ...
-        entry_points={
-            ...
-            "opentelemetry_traces_sampler": [
-                "custom_sampler_name = path.to.sampler.factory.method:CustomSamplerFactory.get_sampler"
-            ]
-        }
-    )
-    # ...
-    class CustomRatioSampler(Sampler):
-        def __init__(rate):
-            # ...
-    # ...
-    class CustomSamplerFactory:
-        @staticmethod
-        get_sampler(sampler_argument):
-            try:
-                rate = float(sampler_argument)
-                return CustomSampler(rate)
-            except ValueError: # In case argument is empty string.
-                return CustomSampler(0.5)
-
-In order to configure you application with a custom sampler's entry point, set the ``OTEL_TRACES_SAMPLER`` environment variable to the key name of the entry point. For example, to configured the
-above sampler, set ``OTEL_TRACES_SAMPLER=custom_sampler_name`` and ``OTEL_TRACES_SAMPLER_ARG=0.5``.
 """
 import abc
 import enum