opentelemetry-sdk: Add ability to refresh process sensitive Resource attributes

.changelog/5280.added

@@ -0,0 +1 @@
+`opentelemetry-sdk`: Add ability to refresh process sensitive Resource attributes

opentelemetry-sdk/src/opentelemetry/sdk/_logs/_internal/__init__.py

@@ -8,6 +8,7 @@
 import concurrent.futures
 import json
 import logging
+import os
 import threading
 import traceback
 import warnings
@@ -24,7 +25,7 @@
     cast,
     overload,
 )
-from weakref import WeakSet
+from weakref import WeakMethod, WeakSet
 
 from typing_extensions import deprecated
 
@@ -59,7 +60,10 @@
 from opentelemetry.sdk.environment_variables._internal import (
     parse_boolean_environment_variable,
 )
-from opentelemetry.sdk.resources import Resource
+from opentelemetry.sdk.resources import (
+    Resource,
+    _get_process_sensitive_resource,
+)
 from opentelemetry.sdk.util import ns_to_iso_str
 from opentelemetry.sdk.util._configurator import RuleBasedConfigurator
 from opentelemetry.sdk.util.instrumentation import (
@@ -693,6 +697,9 @@ def _is_enabled(self) -> bool:
     def _set_logger_config(self, logger_config: _LoggerConfig) -> None:
         self._logger_config = logger_config
 
+    def _set_resource(self, resource: Resource) -> None:
+        self._resource = resource
+
     @property
     def instrumentation_scope(self):
         return self._instrumentation_scope
@@ -812,11 +819,41 @@ def __init__(
         self._logger_cache_lock = Lock()
         self._active_loggers: WeakSet[Logger] = WeakSet()
         self._active_loggers_lock = Lock()
+        if hasattr(os, "register_at_fork"):
+            weak_at_fork = WeakMethod(self._at_fork_reinit)
+
+            def _after_in_child() -> None:
+                if at_fork := weak_at_fork():
+                    at_fork()
+
+            os.register_at_fork(after_in_child=_after_in_child)
+
+    def _at_fork_reinit(self) -> None:
+        self._logger_cache_lock = Lock()
+        self._active_loggers_lock = Lock()
+        self.update_resource(_get_process_sensitive_resource())
 
     @property
     def resource(self):
         return self._resource
 
+    def update_resource(self, resource: Resource) -> None:
+        """Merge a :class:`opentelemetry.sdk.resources.Resource` into this
+        `LoggerProvider`'s resource.
+
+        The resource of all existing :class:`Logger` instances created by this
+        provider is also updated to the merged :class:`opentelemetry.sdk.resources.Resource`.
+
+        Args:
+            resource: The resource to merge into this `LoggerProvider`'s
+                current resource.
+        """
+        with self._active_loggers_lock:
+            self._resource = self._resource.merge(resource)
+            for logger in list(self._active_loggers):
+                # pylint: disable-next=protected-access
+                logger._set_resource(self._resource)
+
     def _get_logger_no_cache(
         self,
         name: str,
@@ -897,7 +934,7 @@ def _set_logger_configurator(
         """
         self._logger_configurator = logger_configurator
         with self._active_loggers_lock:
-            for logger in self._active_loggers:
+            for logger in list(self._active_loggers):
                 # pylint: disable-next=protected-access
                 logger._set_logger_config(
                     self._apply_logger_configurator(

opentelemetry-sdk/src/opentelemetry/sdk/metrics/_internal/__init__.py

@@ -1,6 +1,7 @@
 # Copyright The OpenTelemetry Authors
 # SPDX-License-Identifier: Apache-2.0
 
+import os
 import weakref
 from atexit import register, unregister
 from collections.abc import Callable, Sequence
@@ -51,7 +52,10 @@
 from opentelemetry.sdk.metrics._internal.sdk_configuration import (
     SdkConfiguration,
 )
-from opentelemetry.sdk.resources import Resource
+from opentelemetry.sdk.resources import (
+    Resource,
+    _get_process_sensitive_resource,
+)
 from opentelemetry.sdk.util._configurator import RuleBasedConfigurator
 from opentelemetry.sdk.util.instrumentation import (
     InstrumentationScope,
@@ -526,6 +530,21 @@ def __init__(
             )
             metric_reader._set_meter_provider(self)
 
+        if hasattr(os, "register_at_fork"):
+            weak_at_fork = weakref.WeakMethod(self._at_fork_reinit)
+
+            def _after_in_child() -> None:
+                if at_fork := weak_at_fork():
+                    at_fork()
+
+            os.register_at_fork(after_in_child=_after_in_child)
+
+    def _at_fork_reinit(self) -> None:
+        self._lock = Lock()
+        self._meter_lock = Lock()
+        type(self)._all_metric_readers_lock = Lock()
+        self.update_resource(_get_process_sensitive_resource())
+
     def _set_meter_configurator(
         self, *, meter_configurator: _MeterConfiguratorT
     ):
@@ -543,6 +562,19 @@ def _set_meter_configurator(
                     self._apply_meter_configurator(instrumentation_scope)
                 )
 
+    def update_resource(self, resource: Resource) -> None:
+        """Merge a :class:`opentelemetry.sdk.resources.Resource` into this
+        `MeterProvider`'s resource.
+
+        Args:
+            resource: The resource to merge into this `MeterProvider`'s
+                current resource.
+        """
+        with self._meter_lock:
+            self._sdk_config.resource = self._sdk_config.resource.merge(
+                resource
+            )
+
     def _apply_meter_configurator(
         self, instrumentation_scope: InstrumentationScope
     ) -> _MeterConfig:

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

@@ -287,6 +287,21 @@ def detect(self) -> "Resource":
         """Don't call `Resource.create` here to avoid an infinite loop, instead instantiate `Resource` directly"""
         raise NotImplementedError()
 
+    # pylint: disable-next=no-self-use
+    def is_process_sensitive(self) -> bool:
+        """Return whether this detector depends on the current process identity.
+
+        Process sensitive detectors may return resource attributes that become
+        stale after a process identity change, such as :func:`os.fork`.
+        Detectors returning ``True`` should be re-run after such changes so the
+        resulting :class:`Resource` describes the current process.
+
+        Returns:
+            ``True`` if this detector should be re-run after process identity
+            changes otherwise ``False``.
+        """
+        return False
+
 
 class OTELResourceDetector(ResourceDetector):
     # pylint: disable=no-self-use
@@ -316,6 +331,9 @@ def detect(self) -> "Resource":
 
 class ProcessResourceDetector(ResourceDetector):
     # pylint: disable=no-self-use
+    def is_process_sensitive(self) -> bool:
+        return True
+
     def detect(self) -> "Resource":
         _runtime_version = ".".join(
             map(
@@ -529,6 +547,17 @@ def _build_resource_detectors() -> list["ResourceDetector"]:
     return detectors
 
 
+def _get_process_sensitive_resource() -> Resource:  # pyright: ignore[reportUnusedFunction]
+    return get_aggregated_resources(
+        [
+            detector
+            for detector in _build_resource_detectors()
+            if detector.is_process_sensitive()
+        ],
+        Resource.get_empty(),
+    )
+
+
 def get_aggregated_resources(
     detectors: Sequence["ResourceDetector"],
     initial_resource: Resource | None = None,

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

@@ -50,7 +50,10 @@
 from opentelemetry.sdk.environment_variables._internal import (
     parse_boolean_environment_variable,
 )
-from opentelemetry.sdk.resources import Resource
+from opentelemetry.sdk.resources import (
+    Resource,
+    _get_process_sensitive_resource,
+)
 from opentelemetry.sdk.trace import sampling
 from opentelemetry.sdk.trace._tracer_metrics import create_tracer_metrics
 from opentelemetry.sdk.trace.id_generator import IdGenerator, RandomIdGenerator
@@ -1141,6 +1144,9 @@ def __init__(
     def _set_tracer_config(self, tracer_config: _TracerConfig):
         self._tracer_config = tracer_config
 
+    def _set_resource(self, resource: Resource) -> None:
+        self.resource = resource
+
     def _is_enabled(self) -> bool:
         """If the tracer is not enabled, start_span will create a NonRecordingSpan"""
         return self._tracer_config.is_enabled
@@ -1345,6 +1351,18 @@ def __init__(
         )
         self._tracers_lock = threading.Lock()
         self._tracers: dict[InstrumentationScope, Tracer] = {}
+        if hasattr(os, "register_at_fork"):
+            weak_at_fork = weakref.WeakMethod(self._at_fork_reinit)
+
+            def _after_in_child() -> None:
+                if at_fork := weak_at_fork():
+                    at_fork()
+
+            os.register_at_fork(after_in_child=_after_in_child)
+
+    def _at_fork_reinit(self) -> None:
+        self._tracers_lock = threading.Lock()
+        self.update_resource(_get_process_sensitive_resource())
 
     def _set_tracer_configurator(
         self, *, tracer_configurator: _TracerConfiguratorT
@@ -1367,6 +1385,22 @@ def _set_tracer_configurator(
     def resource(self) -> Resource:
         return self._resource
 
+    def update_resource(self, resource: Resource) -> None:
+        """Merge a :class:`opentelemetry.sdk.resources.Resource` into this
+        `TracerProvider`'s resource.
+
+        The resource of all existing :class:`Tracer` instances created by this
+        provider is also updated to the merged :class:`opentelemetry.sdk.resources.Resource`.
+
+        Args:
+            resource: The resource to merge into this `TracerProvider`'s
+                current resource.
+        """
+        with self._tracers_lock:
+            self._resource = self._resource.merge(resource)
+            for tracer in self._tracers.values():
+                tracer._set_resource(self._resource)  # pylint: disable=protected-access
+
     def _apply_tracer_configurator(
         self, instrumentation_scope: InstrumentationScope
     ):

opentelemetry-sdk/tests/logs/scripts/logger_provider_resource_after_fork.py

@@ -0,0 +1,80 @@
+# Copyright The OpenTelemetry Authors
+# SPDX-License-Identifier: Apache-2.0
+
+import json
+import os
+
+from opentelemetry._logs import LogRecord
+from opentelemetry.sdk._logs import LoggerProvider
+from opentelemetry.sdk._logs.export import (
+    InMemoryLogRecordExporter,
+    SimpleLogRecordProcessor,
+)
+from opentelemetry.sdk.resources import PROCESS_PID
+
+
+# pylint: disable-next=too-many-locals
+def main() -> None:
+    exporter = InMemoryLogRecordExporter()
+    logger_provider = LoggerProvider(shutdown_on_exit=False)
+    logger_provider.add_log_record_processor(
+        SimpleLogRecordProcessor(exporter)
+    )
+    logger = logger_provider.get_logger("cached")
+    parent_pid = os.getpid()
+    parent_resource_pid = logger_provider.resource.attributes[PROCESS_PID]
+    parent_logger_pid = logger.resource.attributes[PROCESS_PID]
+
+    read_fd, write_fd = os.pipe()
+    pid = os.fork()
+    if not pid:
+        os.close(read_fd)
+        child_pid = os.getpid()
+        new_logger = logger_provider.get_logger("new")
+        logger.emit(LogRecord(observed_timestamp=0, body="cached"))
+        new_logger.emit(LogRecord(observed_timestamp=0, body="new"))
+        finished_logs = exporter.get_finished_logs()
+        payload = {
+            "child_pid": child_pid,
+            "provider_pid": logger_provider.resource.attributes[PROCESS_PID],
+            "cached_logger_pid": logger.resource.attributes[PROCESS_PID],
+            "new_logger_pid": new_logger.resource.attributes[PROCESS_PID],
+            "exported_resource_pids": [
+                log.resource.attributes[PROCESS_PID] for log in finished_logs
+            ],
+            "log_bodies": sorted(log.log_record.body for log in finished_logs),
+        }
+        os.write(write_fd, json.dumps(payload).encode())
+        os.close(write_fd)
+        # pylint: disable-next=protected-access
+        os._exit(0)
+
+    os.close(write_fd)
+    child_payload = os.read(read_fd, 4096)
+    os.close(read_fd)
+    _, status = os.waitpid(pid, 0)
+    exit_code = os.waitstatus_to_exitcode(status)
+    if exit_code != 0:
+        raise SystemExit(exit_code)
+
+    print(
+        json.dumps(
+            {
+                "parent_pid": parent_pid,
+                "parent_resource_pid": parent_resource_pid,
+                "parent_logger_pid": parent_logger_pid,
+                "parent_resource_pid_after_fork": logger_provider.resource.attributes[
+                    PROCESS_PID
+                ],
+                "parent_logger_pid_after_fork": logger.resource.attributes[
+                    PROCESS_PID
+                ],
+                "child": json.loads(child_payload.decode()),
+            }
+        ),
+        flush=True,
+    )
+
+
+if __name__ == "__main__":
+    main()