Fix use of built-in samplers in SDK configuration

CHANGELOG.md

@@ -10,6 +10,8 @@ and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0
   ([#3100](https://github.com/open-telemetry/opentelemetry-python/pull/3100))
 - Fix formatting of ConsoleMetricExporter.
   ([#3197](https://github.com/open-telemetry/opentelemetry-python/pull/3197))
+- Fix use of built-in samplers in SDK configuration
+  ([#3176](https://github.com/open-telemetry/opentelemetry-python/pull/3176))
 
 ## Version 1.16.0/0.37b0 (2023-02-17)
 - Change ``__all__`` to be statically defined.

opentelemetry-sdk/pyproject.toml

@@ -41,6 +41,14 @@ sdk = "opentelemetry.sdk.environment_variables"
 [project.entry-points.opentelemetry_id_generator]
 random = "opentelemetry.sdk.trace.id_generator:RandomIdGenerator"
 
+[project.entry-points.opentelemetry_traces_sampler]
+always_on = "opentelemetry.sdk.trace.sampling:_AlwaysOn"
+always_off = "opentelemetry.sdk.trace.sampling:_AlwaysOff"
+parentbased_always_on = "opentelemetry.sdk.trace.sampling:_DefaultOn"
+parentbased_always_off = "opentelemetry.sdk.trace.sampling:_DefaultOff"
+traceidratio = "opentelemetry.sdk.trace.sampling:TraceIdRatioBased"
+parentbased_traceidratio = "opentelemetry.sdk.trace.sampling:ParentBasedTraceIdRatio"
+
 [project.entry-points.opentelemetry_logger_provider]
 sdk_logger_provider = "opentelemetry.sdk._logs:LoggerProvider"
 

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

@@ -304,7 +304,7 @@ def _import_sampler(sampler_name: str) -> Optional[Sampler]:
         return sampler
     except Exception as exc:  # pylint: disable=broad-except
         _logger.warning(
-            "Using default sampler. Failed to initialize custom sampler, %s: %s",
+            "Using default sampler. Failed to initialize sampler, %s: %s",
             sampler_name,
             exc,
         )

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

@@ -393,6 +393,21 @@ def __init__(self, rate: float):
         root = TraceIdRatioBased(rate=rate)
         super().__init__(root=root)
 
+class _AlwaysOff(StaticSampler):
+    def __init__(self, _):
+        super().__init__(Decision.DROP)
+
+class _AlwaysOn(StaticSampler):
+    def __init__(self, _):
+        super().__init__(Decision.RECORD_AND_SAMPLE)
+
+class _DefaultOff(ParentBased):
+    def __init__(self, _):
+        super().__init__(ALWAYS_OFF)
+
+class _DefaultOn(ParentBased):
+    def __init__(self, _):
+        super().__init__(ALWAYS_ON)
 
 _KNOWN_SAMPLERS = {
     "always_on": ALWAYS_ON,