api: conditionally load entrypoints for OTEL_PYTHON_CONTEXT

.changelog/5144.changed

@@ -0,0 +1 @@
+`opentelemetry-api`: conditionally import entrypoints for `opentelemetry_context` only if the `OTEL_PYTHON_CONTEXT` env variable is defined, return `ContextVarsRuntimeContext` otherwise

opentelemetry-api/src/opentelemetry/context/__init__.py

@@ -4,14 +4,14 @@
 from __future__ import annotations
 
 import logging
+import os
 from contextvars import Token
-from os import environ
 from uuid import uuid4
 
 # pylint: disable=wrong-import-position
 from opentelemetry.context.context import Context, _RuntimeContext  # noqa
+from opentelemetry.context.contextvars_context import ContextVarsRuntimeContext
 from opentelemetry.environment_variables import OTEL_PYTHON_CONTEXT
-from opentelemetry.util._importlib_metadata import entry_points
 
 logger = logging.getLogger(__name__)
 
@@ -22,37 +22,29 @@ def _load_runtime_context() -> _RuntimeContext:
     Returns:
         An instance of RuntimeContext.
     """
+    configured_context = os.environ.get(OTEL_PYTHON_CONTEXT)
+    if not configured_context:
+        return ContextVarsRuntimeContext()
 
-    # FIXME use a better implementation of a configuration manager
-    # to avoid having to get configuration values straight from
-    # environment variables
-    default_context = "contextvars_context"
-
-    configured_context = environ.get(OTEL_PYTHON_CONTEXT, default_context)  # type: str
+    # pylint: disable=import-outside-toplevel,no-name-in-module
+    from opentelemetry.util._importlib_metadata import (  # noqa: PLC0415
+        entry_points,
+    )
 
     try:
-        return next(  # type: ignore
-            iter(  # type: ignore
-                entry_points(  # type: ignore
-                    group="opentelemetry_context",
-                    name=configured_context,
+        return next(
+            iter(
+                entry_points(
+                    group="opentelemetry_context", name=configured_context
                 )
             )
         ).load()()
     except Exception:  # pylint: disable=broad-exception-caught
         logger.exception(
-            "Failed to load context: %s, fallback to %s",
+            "Failed to load context: %s, falling back to contextvars_context",
             configured_context,
-            default_context,
         )
-        return next(  # type: ignore
-            iter(  # type: ignore
-                entry_points(  # type: ignore
-                    group="opentelemetry_context",
-                    name=default_context,
-                )
-            )
-        ).load()()
+        return ContextVarsRuntimeContext()
 
 
 _RUNTIME_CONTEXT = _load_runtime_context()

opentelemetry-api/src/opentelemetry/propagate/__init__.py

@@ -63,7 +63,6 @@ def example_route():
 from opentelemetry.context.context import Context
 from opentelemetry.environment_variables import OTEL_PROPAGATORS
 from opentelemetry.propagators import composite, textmap
-from opentelemetry.util._importlib_metadata import entry_points
 
 logger = getLogger(__name__)
 
@@ -109,46 +108,66 @@ def inject(
     get_global_textmap().inject(carrier, context=context, setter=setter)
 
 
-propagators: list[textmap.TextMapPropagator] = []
-
-# Single use variable here to hack black and make lint pass
-environ_propagators = environ.get(
-    OTEL_PROPAGATORS,
-    "tracecontext,baggage",
-)
+def _load_propagators() -> textmap.TextMapPropagator:
+    configured = environ.get(OTEL_PROPAGATORS)
+    if not configured:
+        # pylint: disable=import-outside-toplevel,no-name-in-module
+        from opentelemetry.baggage.propagation import (  # noqa: PLC0415
+            W3CBaggagePropagator,
+        )
 
+        # pylint: disable=import-outside-toplevel,no-name-in-module
+        from opentelemetry.trace.propagation.tracecontext import (  # noqa: PLC0415
+            TraceContextTextMapPropagator,
+        )
 
-for propagator in environ_propagators.split(","):
-    propagator = propagator.strip()
-    if propagator.lower() == "none":
-        logger.debug(
-            "OTEL_PROPAGATORS environment variable contains none, removing all propagators"
+        return composite.CompositePropagator(
+            [TraceContextTextMapPropagator(), W3CBaggagePropagator()]
         )
-        propagators = []
-        break
-    try:
-        propagators.append(
-            next(  # type: ignore
-                iter(  # type: ignore
-                    entry_points(  # type: ignore[misc]
-                        group="opentelemetry_propagator",
-                        name=propagator,
+
+    # pylint: disable=import-outside-toplevel,no-name-in-module
+    from opentelemetry.util._importlib_metadata import (  # noqa: PLC0415
+        entry_points,
+    )
+
+    _propagators: list[textmap.TextMapPropagator] = []
+    for _propagator in configured.split(","):
+        _propagator = _propagator.strip()
+        if _propagator.lower() == "none":
+            logger.debug(
+                "OTEL_PROPAGATORS environment variable contains none, removing all propagators"
+            )
+            return composite.CompositePropagator([])
+        try:
+            _propagators.append(
+                next(  # type: ignore
+                    iter(  # type: ignore
+                        entry_points(  # type: ignore[misc]
+                            group="opentelemetry_propagator",
+                            name=_propagator,
+                        )
                     )
-                )
-            ).load()()
-        )
-    except StopIteration:
-        raise ValueError(
-            f"Propagator {propagator} not found. It is either misspelled or not installed."
-        )
-    except Exception:  # pylint: disable=broad-exception-caught
-        logger.exception("Failed to load propagator: %s", propagator)
-        raise
+                ).load()()
+            )
+        except StopIteration:
+            raise ValueError(
+                f"Propagator {_propagator} not found. It is either misspelled or not installed."
+            )
+        except Exception:  # pylint: disable=broad-exception-caught
+            logger.exception("Failed to load propagator: %s", _propagator)
+            raise
+    return composite.CompositePropagator(_propagators)
+
+
+_HTTP_TEXT_FORMAT: textmap.TextMapPropagator = _load_propagators()
 
+# Deprecated: propagators, environ_propagators and propagator names were never intendended to be part of the public API.
+propagators: list[textmap.TextMapPropagator] = []
+
+environ_propagators = environ.get(OTEL_PROPAGATORS, "tracecontext,baggage")
 
-_HTTP_TEXT_FORMAT: textmap.TextMapPropagator = composite.CompositePropagator(
-    propagators
-)
+for propagator in environ_propagators.split(","):  # type: ignore[assignment]
+    propagator = propagator.strip()
 
 
 def get_global_textmap() -> textmap.TextMapPropagator:

opentelemetry-api/src/opentelemetry/util/_providers.py

@@ -5,8 +5,6 @@
 from os import environ
 from typing import TYPE_CHECKING, TypeVar, cast
 
-from opentelemetry.util._importlib_metadata import entry_points
-
 if TYPE_CHECKING:
     from opentelemetry.metrics import MeterProvider
     from opentelemetry.trace import TracerProvider
@@ -19,6 +17,11 @@
 def _load_provider(
     provider_environment_variable: str, provider: str
 ) -> Provider:  # type: ignore[type-var]
+    # pylint: disable=import-outside-toplevel,no-name-in-module
+    from opentelemetry.util._importlib_metadata import (  # noqa: PLC0415
+        entry_points,
+    )
+
     try:
         provider_name = cast(
             str,