Revert "Enabled custom sampler configuration via env vars (#2972)"

CHANGELOG.md

@@ -7,6 +7,8 @@ and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0
 
 ## Unreleased
 
+- Reverting custom sampler feature until circular dependency issue is fixed.
+  ([#3017](https://github.com/open-telemetry/opentelemetry-python/pull/3017))
 - 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/_configuration/__init__.py

@@ -23,6 +23,7 @@
 from os import environ
 from typing import Dict, Optional, Sequence, Tuple, Type
 
+from pkg_resources import iter_entry_points
 from typing_extensions import Literal
 
 from opentelemetry.environment_variables import (
@@ -54,7 +55,6 @@
 from opentelemetry.sdk.trace import TracerProvider
 from opentelemetry.sdk.trace.export import BatchSpanProcessor, SpanExporter
 from opentelemetry.sdk.trace.id_generator import IdGenerator
-from opentelemetry.sdk.util import _import_config_components
 from opentelemetry.semconv.resource import ResourceAttributes
 from opentelemetry.trace import set_tracer_provider
 
@@ -226,6 +226,26 @@ def _init_logging(
     logging.getLogger().addHandler(handler)
 
 
+def _import_config_components(
+    selected_components, entry_point_name
+) -> Sequence[Tuple[str, object]]:
+    component_entry_points = {
+        ep.name: ep for ep in iter_entry_points(entry_point_name)
+    }
+    component_impls = []
+    for selected_component in selected_components:
+        entry_point = component_entry_points.get(selected_component, None)
+        if not entry_point:
+            raise RuntimeError(
+                f"Requested component '{selected_component}' not found in entry points for '{entry_point_name}'"
+            )
+
+        component_impl = entry_point.load()
+        component_impls.append((selected_component, component_impl))
+
+    return component_impls
+
+
 def _import_exporters(
     trace_exporter_names: Sequence[str],
     metric_exporter_names: Sequence[str],
@@ -267,9 +287,10 @@ def _import_exporters(
 
 
 def _import_id_generator(id_generator_name: str) -> IdGenerator:
-    id_generator_name, id_generator_impl = _import_config_components(
+    # pylint: disable=unbalanced-tuple-unpacking
+    [(id_generator_name, id_generator_impl)] = _import_config_components(
         [id_generator_name.strip()], "opentelemetry_id_generator"
-    )[0]
+    )
 
     if issubclass(id_generator_impl, IdGenerator):
         return id_generator_impl

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 +73,8 @@
     * 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``.
 
@@ -96,53 +97,20 @@
     # 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
 import os
 from logging import getLogger
 from types import MappingProxyType
-from typing import Callable, Optional, Sequence
+from typing import Optional, Sequence
 
 # pylint: disable=unused-import
 from opentelemetry.context import Context
 from opentelemetry.sdk.environment_variables import (
     OTEL_TRACES_SAMPLER,
     OTEL_TRACES_SAMPLER_ARG,
 )
-from opentelemetry.sdk.util import _import_config_components
 from opentelemetry.trace import Link, SpanKind, get_current_span
 from opentelemetry.trace.span import TraceState
 from opentelemetry.util.types import Attributes
@@ -193,9 +161,6 @@ def __init__(
         self.trace_state = trace_state
 
 
-_OTEL_SAMPLER_ENTRY_POINT_GROUP = "opentelemetry_traces_sampler"
-
-
 class Sampler(abc.ABC):
     @abc.abstractmethod
     def should_sample(
@@ -407,48 +372,26 @@ def __init__(self, rate: float):
 
 
 def _get_from_env_or_default() -> Sampler:
-    traces_sampler_name = os.getenv(
+    trace_sampler = os.getenv(
         OTEL_TRACES_SAMPLER, "parentbased_always_on"
     ).lower()
+    if trace_sampler not in _KNOWN_SAMPLERS:
+        _logger.warning("Couldn't recognize sampler %s.", trace_sampler)
+        trace_sampler = "parentbased_always_on"
 
-    if traces_sampler_name in _KNOWN_SAMPLERS:
-        if traces_sampler_name in ("traceidratio", "parentbased_traceidratio"):
-            try:
-                rate = float(os.getenv(OTEL_TRACES_SAMPLER_ARG))
-            except ValueError:
-                _logger.warning(
-                    "Could not convert TRACES_SAMPLER_ARG to float."
-                )
-                rate = 1.0
-            return _KNOWN_SAMPLERS[traces_sampler_name](rate)
-        return _KNOWN_SAMPLERS[traces_sampler_name]
-    try:
-        traces_sampler_factory = _import_sampler_factory(traces_sampler_name)
-        sampler_arg = os.getenv(OTEL_TRACES_SAMPLER_ARG, "")
-        traces_sampler = traces_sampler_factory(sampler_arg)
-        if not isinstance(traces_sampler, Sampler):
-            message = f"Traces sampler factory, {traces_sampler_factory}, produced output, {traces_sampler}, which is not a Sampler object."
-            _logger.warning(message)
-            raise ValueError(message)
-        return traces_sampler
-    except Exception as exc:  # pylint: disable=broad-except
-        _logger.warning(
-            "Using default sampler. Failed to initialize custom sampler, %s: %s",
-            traces_sampler_name,
-            exc,
-        )
-        return _KNOWN_SAMPLERS["parentbased_always_on"]
+    if trace_sampler in ("traceidratio", "parentbased_traceidratio"):
+        try:
+            rate = float(os.getenv(OTEL_TRACES_SAMPLER_ARG))
+        except ValueError:
+            _logger.warning("Could not convert TRACES_SAMPLER_ARG to float.")
+            rate = 1.0
+        return _KNOWN_SAMPLERS[trace_sampler](rate)
+
+    return _KNOWN_SAMPLERS[trace_sampler]
 
 
 def _get_parent_trace_state(parent_context) -> Optional["TraceState"]:
     parent_span_context = get_current_span(parent_context).get_span_context()
     if parent_span_context is None or not parent_span_context.is_valid:
         return None
     return parent_span_context.trace_state
-
-
-def _import_sampler_factory(sampler_name: str) -> Callable[[str], Sampler]:
-    _, sampler_impl = _import_config_components(
-        [sampler_name.strip()], _OTEL_SAMPLER_ENTRY_POINT_GROUP
-    )[0]
-    return sampler_impl

opentelemetry-sdk/src/opentelemetry/sdk/util/__init__.py

@@ -14,11 +14,11 @@
 
 import datetime
 import threading
-from collections import OrderedDict, abc, deque
-from typing import List, Optional, Sequence, Tuple
+from collections import OrderedDict, deque
+from collections.abc import MutableMapping, Sequence
+from typing import Optional
 
 from deprecated import deprecated
-from pkg_resources import iter_entry_points
 
 
 def ns_to_iso_str(nanoseconds):
@@ -41,27 +41,7 @@ def get_dict_as_key(labels):
     )
 
 
-def _import_config_components(
-    selected_components: List[str], entry_point_name: str
-) -> Sequence[Tuple[str, object]]:
-    component_entry_points = {
-        ep.name: ep for ep in iter_entry_points(entry_point_name)
-    }
-    component_impls = []
-    for selected_component in selected_components:
-        entry_point = component_entry_points.get(selected_component, None)
-        if not entry_point:
-            raise RuntimeError(
-                f"Requested component '{selected_component}' not found in entry points for '{entry_point_name}'"
-            )
-
-        component_impl = entry_point.load()
-        component_impls.append((selected_component, component_impl))
-
-    return component_impls
-
-
-class BoundedList(abc.Sequence):
+class BoundedList(Sequence):
     """An append only list with a fixed max size.
 
     Calls to `append` and `extend` will drop the oldest elements if there is
@@ -112,7 +92,7 @@ def from_seq(cls, maxlen, seq):
 
 
 @deprecated(version="1.4.0")  # type: ignore
-class BoundedDict(abc.MutableMapping):
+class BoundedDict(MutableMapping):
     """An ordered dict with a fixed max capacity.
 
     Oldest elements are dropped when the dict is full and a new element is

opentelemetry-sdk/tests/test_configurator.py

@@ -257,7 +257,7 @@ def test_trace_init_otlp(self):
 
     @patch.dict(environ, {OTEL_PYTHON_ID_GENERATOR: "custom_id_generator"})
     @patch("opentelemetry.sdk._configuration.IdGenerator", new=IdGenerator)
-    @patch("opentelemetry.sdk.util.iter_entry_points")
+    @patch("opentelemetry.sdk._configuration.iter_entry_points")
     def test_trace_init_custom_id_generator(self, mock_iter_entry_points):
         mock_iter_entry_points.configure_mock(
             return_value=[