feat(config): add service resource detector support for declarative config (#5003)

* config: add resource and propagator creation from declarative config

Implements create_resource() and create_propagator()/configure_propagator()
for the declarative file configuration. Resource creation does not read
OTEL_RESOURCE_ATTRIBUTES or run any detectors (matches Java/JS SDK behavior).
Propagator configuration always calls set_global_textmap to override Python's
default tracecontext+baggage, setting a noop CompositePropagator when no
propagator is configured.

Assisted-by: Claude Sonnet 4.6

* update changelog with PR number

Assisted-by: Claude Sonnet 4.6

* fix pylint, pyright and ruff errors in resource/propagator config

- _resource.py: refactor _coerce_attribute_value to dispatch table to
  avoid too-many-return-statements; fix short variable names k/v ->
  attr_key/attr_val; fix return type of _sdk_default_attributes to
  dict[str, str] to satisfy pyright
- _propagator.py: rename short variable names e -> exc, p -> propagator
- test_resource.py: move imports to top level; split TestCreateResource
  (25 methods) into three focused classes to satisfy too-many-public-methods
- test_propagator.py: add pylint disable for protected-access

Assisted-by: Claude Sonnet 4.6

* address review feedback: use _DEFAULT_RESOURCE, fix bool_array coercion

- replace _sdk_default_attributes() with _DEFAULT_RESOURCE from resources module
- move _coerce_bool into dispatch tables for both scalar and array bool types,
  fixing a bug where bool_array with string values like "false" would coerce
  incorrectly via plain bool() (non-empty string -> True)
- add test for bool_array with string values to cover the bug

Assisted-by: Claude Sonnet 4.6

* fix linter

* address review feedback: single coercion table, simplify attributes merge

- collapse _SCALAR_COERCIONS and _ARRAY_COERCIONS into a single _COERCIONS
  dict using an _array() factory, reducing _coerce_attribute_value to two lines
- process attributes_list before attributes so explicit attributes naturally
  overwrite list entries without needing an explicit guard

Assisted-by: Claude Sonnet 4.6

* use Callable type annotation on _array helper

Assisted-by: Claude Sonnet 4.6

* add detection infrastructure foundations for resource detectors

Adds _run_detectors() stub and _filter_attributes() to create_resource(),
providing the shared scaffolding for detector PRs to build on. Detectors
are opt-in: nothing runs unless explicitly listed under
detection_development.detectors in the config. The include/exclude
attribute filter mirrors other SDK behaviour.

Assisted-by: Claude Sonnet 4.6

* move service.name default into base resource

Merges service.name=unknown_service into base before running detectors,
so detectors (e.g. service) can override it. Previously it was added to
config_attrs and merged last, which would have silently overridden any
detector-provided service.name.

Assisted-by: Claude Sonnet 4.6

* remove unused logging import from _propagator.py

Assisted-by: Claude Sonnet 4.6

* wire service resource detector in declarative config

Adds service detector support to _run_detectors(): sets a random UUID
for service.instance.id and reads OTEL_SERVICE_NAME for service.name
if set. Explicit config attributes still take priority (merged last).

Assisted-by: Claude Sonnet 4.6

* add changelog entry for service resource detector (#5003)

Assisted-by: Claude Sonnet 4.6

---------

Co-authored-by: Aaron Abbott <aaronabbott@google.com>

Author: MikeGoldsmith

CHANGELOG.md

@@ -12,6 +12,9 @@ and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0
 
 ## Unreleased
 
+- `opentelemetry-sdk`: Add `service` resource detector support to declarative file configuration via `detection_development.detectors[].service`
+  ([#5003](https://github.com/open-telemetry/opentelemetry-python/pull/5003))
+
 ## Version 1.41.0/0.62b0 (2026-04-09)
 
 - `opentelemetry-sdk`: Add `host` resource detector support to declarative file configuration via `detection_development.detectors[].host`

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

@@ -16,6 +16,8 @@
 
 import fnmatch
 import logging
+import os
+import uuid
 from typing import Callable, Optional
 from urllib import parse
 
@@ -28,6 +30,8 @@
 from opentelemetry.sdk._configuration.models import Resource as ResourceConfig
 from opentelemetry.sdk.resources import (
     _DEFAULT_RESOURCE,
+    OTEL_SERVICE_NAME,
+    SERVICE_INSTANCE_ID,
     SERVICE_NAME,
     ProcessResourceDetector,
     Resource,
@@ -152,6 +156,15 @@ def _run_detectors(
     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)
 

opentelemetry-sdk/tests/_configuration/test_resource.py

@@ -33,6 +33,7 @@
     HOST_NAME,
     PROCESS_PID,
     PROCESS_RUNTIME_NAME,
+    SERVICE_INSTANCE_ID,
     SERVICE_NAME,
     TELEMETRY_SDK_LANGUAGE,
     TELEMETRY_SDK_NAME,
@@ -307,6 +308,79 @@ def test_attributes_list_invalid_pair_skipped(self):
         self.assertTrue(any("no-equals" in msg for msg in cm.output))
 
 
+class TestServiceResourceDetector(unittest.TestCase):
+    @staticmethod
+    def _config_with_service() -> ResourceConfig:
+        return ResourceConfig(
+            detection_development=ExperimentalResourceDetection(
+                detectors=[ExperimentalResourceDetector(service={})]
+            )
+        )
+
+    def test_service_detector_adds_instance_id(self):
+        resource = create_resource(self._config_with_service())
+        self.assertIn(SERVICE_INSTANCE_ID, resource.attributes)
+
+    def test_service_instance_id_is_unique_per_call(self):
+        r1 = create_resource(self._config_with_service())
+        r2 = create_resource(self._config_with_service())
+        self.assertNotEqual(
+            r1.attributes[SERVICE_INSTANCE_ID],
+            r2.attributes[SERVICE_INSTANCE_ID],
+        )
+
+    def test_service_detector_reads_otel_service_name_env_var(self):
+        with patch.dict(os.environ, {"OTEL_SERVICE_NAME": "my-service"}):
+            resource = create_resource(self._config_with_service())
+        self.assertEqual(resource.attributes[SERVICE_NAME], "my-service")
+
+    def test_service_detector_no_env_var_leaves_default_service_name(self):
+        with patch.dict(os.environ, {}, clear=True):
+            resource = create_resource(self._config_with_service())
+        self.assertEqual(resource.attributes[SERVICE_NAME], "unknown_service")
+
+    def test_explicit_service_name_overrides_env_var(self):
+        """Config attributes win over the service detector's env-var value."""
+        config = ResourceConfig(
+            attributes=[
+                AttributeNameValue(name="service.name", value="explicit-svc")
+            ],
+            detection_development=ExperimentalResourceDetection(
+                detectors=[ExperimentalResourceDetector(service={})]
+            ),
+        )
+        with patch.dict(os.environ, {"OTEL_SERVICE_NAME": "env-svc"}):
+            resource = create_resource(config)
+        self.assertEqual(resource.attributes[SERVICE_NAME], "explicit-svc")
+
+    def test_service_detector_not_run_when_absent(self):
+        resource = create_resource(ResourceConfig())
+        self.assertNotIn(SERVICE_INSTANCE_ID, resource.attributes)
+
+    def test_service_detector_not_run_when_detection_development_is_none(self):
+        resource = create_resource(ResourceConfig(detection_development=None))
+        self.assertNotIn(SERVICE_INSTANCE_ID, resource.attributes)
+
+    def test_service_detector_also_includes_sdk_defaults(self):
+        resource = create_resource(self._config_with_service())
+        self.assertEqual(resource.attributes[TELEMETRY_SDK_LANGUAGE], "python")
+        self.assertIn(TELEMETRY_SDK_VERSION, resource.attributes)
+
+    def test_included_filter_limits_service_attributes(self):
+        config = ResourceConfig(
+            detection_development=ExperimentalResourceDetection(
+                detectors=[ExperimentalResourceDetector(service={})],
+                attributes=IncludeExclude(included=["service.instance.id"]),
+            )
+        )
+        with patch.dict(os.environ, {"OTEL_SERVICE_NAME": "my-service"}):
+            resource = create_resource(config)
+        self.assertIn(SERVICE_INSTANCE_ID, resource.attributes)
+        # service.name comes from the filter-excluded detector output, but the
+        # default "unknown_service" is still added by create_resource directly
+        self.assertEqual(resource.attributes[SERVICE_NAME], "unknown_service")
+
+
 class TestHostResourceDetector(unittest.TestCase):
     @staticmethod
     def _config_with_host() -> ResourceConfig: