wire process resource detector in declarative config

When `resource.detection_development.detectors[].process` is set in
the config file, run `ProcessResourceDetector` and merge its output
into the resource. Explicit config attributes take priority over
detector-provided values.

Assisted-by: Claude Sonnet 4.6

Author: MikeGoldsmith

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

@@ -29,6 +29,7 @@
 from opentelemetry.sdk.resources import (
     _DEFAULT_RESOURCE,
     SERVICE_NAME,
+    ProcessResourceDetector,
     Resource,
 )
 
@@ -45,7 +46,7 @@ def _array(coerce: Callable) -> Callable:
     return lambda value: [coerce(item) for item in value]
 
 
-# Unified dispatch table for all attribute type coercions
+# Dispatch table mapping AttributeType to its coercion callable
 _COERCIONS = {
     AttributeType.string: str,
     AttributeType.int: int,
@@ -152,6 +153,8 @@ def _run_detectors(
     is updated in-place; later detectors overwrite earlier ones for the
     same key.
     """
+    if detector_config.process is not None:
+        detected_attrs.update(ProcessResourceDetector().detect().attributes)
 
 
 def _filter_attributes(

opentelemetry-sdk/tests/_configuration/test_resource.py

@@ -13,16 +13,21 @@
 # limitations under the License.
 
 import os
+import sys
 import unittest
 from unittest.mock import patch
 
 from opentelemetry.sdk._configuration._resource import create_resource
 from opentelemetry.sdk._configuration.models import (
     AttributeNameValue,
     AttributeType,
+    ExperimentalResourceDetection,
+    ExperimentalResourceDetector,
 )
 from opentelemetry.sdk._configuration.models import Resource as ResourceConfig
 from opentelemetry.sdk.resources import (
+    PROCESS_PID,
+    PROCESS_RUNTIME_NAME,
     SERVICE_NAME,
     TELEMETRY_SDK_LANGUAGE,
     TELEMETRY_SDK_NAME,
@@ -295,3 +300,69 @@ def test_attributes_list_invalid_pair_skipped(self):
         self.assertEqual(resource.attributes["foo"], "bar")
         self.assertNotIn("no-equals", resource.attributes)
         self.assertTrue(any("no-equals" in msg for msg in cm.output))
+
+
+class TestProcessResourceDetector(unittest.TestCase):
+    def _config_with_process(self) -> ResourceConfig:
+        return ResourceConfig(
+            detection_development=ExperimentalResourceDetection(
+                detectors=[ExperimentalResourceDetector(process={})]
+            )
+        )
+
+    def test_process_detector_adds_process_attributes(self):
+        resource = create_resource(self._config_with_process())
+        self.assertIn(PROCESS_PID, resource.attributes)
+        self.assertEqual(resource.attributes[PROCESS_PID], os.getpid())
+        self.assertEqual(
+            resource.attributes[PROCESS_RUNTIME_NAME],
+            sys.implementation.name,
+        )
+
+    def test_process_detector_also_includes_sdk_defaults(self):
+        resource = create_resource(self._config_with_process())
+        self.assertEqual(resource.attributes[TELEMETRY_SDK_LANGUAGE], "python")
+        self.assertIn(TELEMETRY_SDK_VERSION, resource.attributes)
+
+    def test_process_detector_not_run_when_absent(self):
+        resource = create_resource(ResourceConfig())
+        self.assertNotIn(PROCESS_PID, resource.attributes)
+
+    def test_process_detector_not_run_when_detection_development_is_none(self):
+        resource = create_resource(ResourceConfig(detection_development=None))
+        self.assertNotIn(PROCESS_PID, resource.attributes)
+
+    def test_process_detector_not_run_when_detectors_list_empty(self):
+        config = ResourceConfig(
+            detection_development=ExperimentalResourceDetection(detectors=[])
+        )
+        resource = create_resource(config)
+        self.assertNotIn(PROCESS_PID, resource.attributes)
+
+    def test_explicit_attributes_override_process_detector(self):
+        """Config attributes win over detector-provided values."""
+        config = ResourceConfig(
+            attributes=[
+                AttributeNameValue(
+                    name="process.pid", value=99999, type=AttributeType.int
+                )
+            ],
+            detection_development=ExperimentalResourceDetection(
+                detectors=[ExperimentalResourceDetector(process={})]
+            ),
+        )
+        resource = create_resource(config)
+        self.assertEqual(resource.attributes[PROCESS_PID], 99999)
+
+    def test_multiple_detector_entries_run_process_once(self):
+        """Multiple detector list entries each with process={} should still work."""
+        config = ResourceConfig(
+            detection_development=ExperimentalResourceDetection(
+                detectors=[
+                    ExperimentalResourceDetector(process={}),
+                    ExperimentalResourceDetector(process={}),
+                ]
+            )
+        )
+        resource = create_resource(config)
+        self.assertEqual(resource.attributes[PROCESS_PID], os.getpid())