feat(config): generic resource detector plugin loading for declarative config

CHANGELOG.md

@@ -12,6 +12,8 @@ and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0
 
 ## Unreleased
 
+- `opentelemetry-sdk`: add generic resource detector plugin loading to declarative file configuration via the `opentelemetry_resource_detector` entry point group
+  ([#5129](https://github.com/open-telemetry/opentelemetry-python/pull/5129))
 - `opentelemetry-sdk`: add `additional_properties` support to generated config models via custom `datamodel-codegen` template, enabling plugin/custom component names to flow through typed dataclasses
   ([#5131](https://github.com/open-telemetry/opentelemetry-python/pull/5131))
 - Fix incorrect code example in `create_tracer()` docstring

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

@@ -14,13 +14,15 @@
 
 from __future__ import annotations
 
+import dataclasses
 import fnmatch
 import logging
 import os
 import uuid
 from typing import Callable, Optional
 from urllib import parse
 
+from opentelemetry.sdk._configuration._common import load_entry_point
 from opentelemetry.sdk._configuration.models import (
     AttributeNameValue,
     AttributeType,
@@ -37,7 +39,6 @@
     Resource,
     _HostResourceDetector,
 )
-from opentelemetry.util._importlib_metadata import entry_points
 
 _logger = logging.getLogger(__name__)
 
@@ -146,55 +147,56 @@ def create_resource(config: Optional[ResourceConfig]) -> Resource:
     return result.merge(config_resource)
 
 
+def _detect_service(_config) -> dict[str, object]:
+    """Service detector: generates instance ID and reads OTEL_SERVICE_NAME."""
+    attrs: dict[str, object] = {
+        SERVICE_INSTANCE_ID: str(uuid.uuid4()),
+    }
+    service_name = os.environ.get(OTEL_SERVICE_NAME)
+    if service_name:
+        attrs[SERVICE_NAME] = service_name
+    return attrs
+
+
+_RESOURCE_DETECTOR_REGISTRY: dict = {
+    "service": _detect_service,
+    "host": lambda _: dict(_HostResourceDetector().detect().attributes),
+    "process": lambda _: dict(ProcessResourceDetector().detect().attributes),
+}
+
+
 def _run_detectors(
     detector_config: ExperimentalResourceDetector,
     detected_attrs: dict[str, object],
 ) -> None:
-    """Run any detectors present in a single detector config entry.
+    """Run detectors present in a single detector config entry.
 
-    Each detector PR adds its own branch here. The detected_attrs dict
-    is updated in-place; later detectors overwrite earlier ones for the
-    same key.
+    Known detectors (service, host, process) are handled directly via
+    _RESOURCE_DETECTOR_REGISTRY. All other detectors — including known
+    schema fields like container that require contrib packages, and
+    unknown plugin detectors captured in additional_properties — are
+    loaded via the ``opentelemetry_resource_detector`` entry point group.
+
+    The detected_attrs dict is updated in-place; later detectors overwrite
+    earlier ones for the same key.
     """
-    if detector_config.service is not None:
-        attrs: dict[str, object] = {
-            SERVICE_INSTANCE_ID: str(uuid.uuid4()),
-        }
-        service_name = os.environ.get(OTEL_SERVICE_NAME)
-        if service_name:
-            attrs[SERVICE_NAME] = service_name
-        detected_attrs.update(attrs)
-
-    if detector_config.host is not None:
-        detected_attrs.update(_HostResourceDetector().detect().attributes)
-
-    if detector_config.container is not None:
-        # The container detector is not part of the core SDK. It is provided
-        # by the opentelemetry-resource-detector-containerid contrib package,
-        # which registers itself under the opentelemetry_resource_detector
-        # entry point group as "container". Loading via entry point matches
-        # the env-var config counterpart (OTEL_EXPERIMENTAL_RESOURCE_DETECTORS)
-        # and avoids a hard import dependency on contrib. See also:
-        # https://github.com/open-telemetry/opentelemetry-configuration/issues/570
-        ep = next(
-            iter(
-                entry_points(
-                    group="opentelemetry_resource_detector", name="container"
-                )
-            ),
-            None,
-        )
-        if ep is None:
-            _logger.warning(
-                "container resource detector requested but "
-                "'opentelemetry-resource-detector-containerid' is not "
-                "installed; install it to enable container detection"
+    for name in dataclasses.fields(detector_config):
+        value = getattr(detector_config, name.name, None)
+        if value is None:
+            continue
+        if name.name in _RESOURCE_DETECTOR_REGISTRY:
+            detected_attrs.update(
+                _RESOURCE_DETECTOR_REGISTRY[name.name](value)
             )
         else:
-            detected_attrs.update(ep.load()().detect().attributes)
+            cls = load_entry_point(
+                "opentelemetry_resource_detector", name.name
+            )
+            detected_attrs.update(cls().detect().attributes)
 
-    if detector_config.process is not None:
-        detected_attrs.update(ProcessResourceDetector().detect().attributes)
+    for name in detector_config.additional_properties:
+        cls = load_entry_point("opentelemetry_resource_detector", name)
+        detected_attrs.update(cls().detect().attributes)
 
 
 def _filter_attributes(

opentelemetry-sdk/tests/_configuration/test_resource.py

@@ -18,6 +18,7 @@
 import unittest
 from unittest.mock import MagicMock, patch
 
+from opentelemetry.sdk._configuration._exceptions import ConfigurationError
 from opentelemetry.sdk._configuration._resource import create_resource
 from opentelemetry.sdk._configuration.models import (
     AttributeNameValue,
@@ -478,23 +479,14 @@ def test_container_detector_not_run_when_detectors_list_empty(self):
         resource = create_resource(config)
         self.assertNotIn(CONTAINER_ID, resource.attributes)
 
-    def test_container_detector_warns_when_package_missing(self):
-        """A warning is logged when the contrib entry point is not found."""
+    def test_container_detector_raises_when_package_missing(self):
+        """ConfigurationError is raised when the contrib entry point is not found."""
         with patch(
-            "opentelemetry.sdk._configuration._resource.entry_points",
+            "opentelemetry.sdk._configuration._common.entry_points",
             return_value=[],
         ):
-            with self.assertLogs(
-                "opentelemetry.sdk._configuration._resource", level="WARNING"
-            ) as cm:
-                resource = create_resource(self._config_with_container())
-        self.assertNotIn(CONTAINER_ID, resource.attributes)
-        self.assertTrue(
-            any(
-                "opentelemetry-resource-detector-containerid" in msg
-                for msg in cm.output
-            )
-        )
+            with self.assertRaises(ConfigurationError):
+                create_resource(self._config_with_container())
 
     def test_container_detector_uses_contrib_when_available(self):
         """When the contrib entry point is registered, container.id is detected."""
@@ -505,7 +497,7 @@ def test_container_detector_uses_contrib_when_available(self):
         mock_ep.load.return_value = mock_detector
 
         with patch(
-            "opentelemetry.sdk._configuration._resource.entry_points",
+            "opentelemetry.sdk._configuration._common.entry_points",
             return_value=[mock_ep],
         ):
             resource = create_resource(self._config_with_container())
@@ -529,7 +521,7 @@ def test_explicit_attributes_override_container_detector(self):
             ),
         )
         with patch(
-            "opentelemetry.sdk._configuration._resource.entry_points",
+            "opentelemetry.sdk._configuration._common.entry_points",
             return_value=[mock_ep],
         ):
             resource = create_resource(config)
@@ -602,3 +594,40 @@ def test_multiple_detector_entries_run_process_once(self):
         )
         resource = create_resource(config)
         self.assertEqual(resource.attributes[PROCESS_PID], os.getpid())
+
+
+class TestPluginResourceDetector(unittest.TestCase):
+    def test_plugin_detector_loaded_via_entry_point(self):
+        mock_resource = Resource({"custom.attr": "value"})
+        mock_detector = MagicMock()
+        mock_detector.return_value.detect.return_value = mock_resource
+        mock_ep = MagicMock()
+        mock_ep.load.return_value = mock_detector
+
+        config = ResourceConfig(
+            detection_development=ExperimentalResourceDetection(
+                # pylint: disable=unexpected-keyword-arg
+                detectors=[ExperimentalResourceDetector(my_custom_detector={})]
+            )
+        )
+        with patch(
+            "opentelemetry.sdk._configuration._common.entry_points",
+            return_value=[mock_ep],
+        ):
+            resource = create_resource(config)
+
+        self.assertEqual(resource.attributes["custom.attr"], "value")
+
+    def test_unknown_detector_raises_configuration_error(self):
+        config = ResourceConfig(
+            detection_development=ExperimentalResourceDetection(
+                # pylint: disable=unexpected-keyword-arg
+                detectors=[ExperimentalResourceDetector(no_such_detector={})]
+            )
+        )
+        with patch(
+            "opentelemetry.sdk._configuration._common.entry_points",
+            return_value=[],
+        ):
+            with self.assertRaises(ConfigurationError):
+                create_resource(config)