[Python Otel] Allow start observability without context manager (#35932)

Allow start observability globally with a new API `start_open_telemetry_observability`.

<!--

If you know who should review your pull request, please assign it to that
person, otherwise the pull request would get assigned randomly.

If your pull request is for a specific language, please add the appropriate
lang label.

-->

Closes #35932

PiperOrigin-RevId: 612639020

examples/python/observability/observability_greeter_client.py

@@ -47,16 +47,16 @@ def run():
     provider = MeterProvider(metric_readers=[reader])
     otel_plugin = BaseOpenTelemetryPlugin(provider)
 
-    with grpc_observability.OpenTelemetryObservability(plugins=[otel_plugin]):
-        with grpc.insecure_channel(target="localhost:50051") as channel:
-            stub = helloworld_pb2_grpc.GreeterStub(channel)
-            try:
-                response = stub.SayHello(
-                    helloworld_pb2.HelloRequest(name="You")
-                )
-                print(f"Greeter client received: {response.message}")
-            except grpc.RpcError as rpc_error:
-                print("Call failed with code: ", rpc_error.code())
+    grpc_observability.start_open_telemetry_observability(plugins=[otel_plugin])
+
+    with grpc.insecure_channel(target="localhost:50051") as channel:
+        stub = helloworld_pb2_grpc.GreeterStub(channel)
+        try:
+            response = stub.SayHello(helloworld_pb2.HelloRequest(name="You"))
+            print(f"Greeter client received: {response.message}")
+        except grpc.RpcError as rpc_error:
+            print("Call failed with code: ", rpc_error.code())
+    grpc_observability.end_open_telemetry_observability()
 
     # Sleep to make sure all metrics are exported.
     time.sleep(5)

examples/python/observability/observability_greeter_server.py

@@ -57,22 +57,24 @@ def serve():
     provider = MeterProvider(metric_readers=[reader])
     otel_plugin = BaseOpenTelemetryPlugin(provider)
 
-    with grpc_observability.OpenTelemetryObservability(plugins=[otel_plugin]):
-        server = grpc.server(
-            thread_pool=futures.ThreadPoolExecutor(max_workers=10),
-        )
-        helloworld_pb2_grpc.add_GreeterServicer_to_server(Greeter(), server)
-        server.add_insecure_port("[::]:" + _SERVER_PORT)
-        server.start()
-        print("Server started, listening on " + _SERVER_PORT)
-
-        # Sleep to make sure client made RPC call and all metrics are exported.
-        time.sleep(10)
-        print("Metrics exported on Server side:")
-        for metric in all_metrics:
-            print(metric)
-
-        server.stop(0)
+    grpc_observability.start_open_telemetry_observability(plugins=[otel_plugin])
+
+    server = grpc.server(
+        thread_pool=futures.ThreadPoolExecutor(max_workers=10),
+    )
+    helloworld_pb2_grpc.add_GreeterServicer_to_server(Greeter(), server)
+    server.add_insecure_port("[::]:" + _SERVER_PORT)
+    server.start()
+    print("Server started, listening on " + _SERVER_PORT)
+
+    # Sleep to make sure client made RPC call and all metrics are exported.
+    time.sleep(10)
+    print("Metrics exported on Server side:")
+    for metric in all_metrics:
+        print(metric)
+
+    server.stop(0)
+    grpc_observability.end_open_telemetry_observability()
 
 
 if __name__ == "__main__":

src/python/grpcio_observability/grpc_observability/__init__.py

@@ -15,6 +15,17 @@
 from grpc_observability._open_telemetry_observability import (
     OpenTelemetryObservability,
 )
+from grpc_observability._open_telemetry_observability import (
+    end_open_telemetry_observability,
+)
+from grpc_observability._open_telemetry_observability import (
+    start_open_telemetry_observability,
+)
 from grpc_observability._open_telemetry_plugin import OpenTelemetryPlugin
 
-__all__ = ("OpenTelemetryObservability", "OpenTelemetryPlugin")
+__all__ = (
+    "OpenTelemetryObservability",
+    "OpenTelemetryPlugin",
+    "start_open_telemetry_observability",
+    "end_open_telemetry_observability",
+)

src/python/grpcio_observability/grpc_observability/_open_telemetry_observability.py

@@ -13,6 +13,7 @@
 # limitations under the License.
 
 import logging
+import threading
 import time
 from typing import Any, Iterable, Optional
 
@@ -54,6 +55,22 @@ GRPC_STATUS_CODE_TO_STRING = {
     grpc.StatusCode.DATA_LOSS: "DATA_LOSS",
 }
 
+_observability_lock: threading.RLock = threading.RLock()
+_OPEN_TELEMETRY_OBSERVABILITY: Optional["OpenTelemetryObservability"] = None
+
+
+def start_open_telemetry_observability(
+    *,
+    plugins: Optional[Iterable[OpenTelemetryPlugin]] = None,
+) -> None:
+    _start_open_telemetry_observability(
+        OpenTelemetryObservability(plugins=plugins)
+    )
+
+
+def end_open_telemetry_observability() -> None:
+    _end_open_telemetry_observability()
+
 
 # pylint: disable=no-self-use
 class OpenTelemetryObservability(grpc._observability.ObservabilityPlugin):
@@ -66,7 +83,6 @@ class OpenTelemetryObservability(grpc._observability.ObservabilityPlugin):
     """
 
     exporter: "grpc_observability.Exporter"
-    plugins: Iterable[OpenTelemetryPlugin]
 
     def __init__(
         self,
@@ -80,13 +96,20 @@ class OpenTelemetryObservability(grpc._observability.ObservabilityPlugin):
 
         self.exporter = _OpenTelemetryExporterDelegator(_plugins)
 
+    def __enter__(self):
+        _start_open_telemetry_observability(self)
+        return self
+
+    def __exit__(self, exc_type, exc_val, exc_tb) -> None:
+        _end_open_telemetry_observability()
+
+    def observability_init(self):
         try:
             _cyobservability.activate_stats()
             self.set_stats(True)
         except Exception as e:  # pylint: disable=broad-except
             raise ValueError(f"Activate observability metrics failed with: {e}")
 
-    def __enter__(self):
         try:
             _cyobservability.cyobservability_init(self.exporter)
         # TODO(xuanwn): Use specific exceptons
@@ -94,12 +117,8 @@ class OpenTelemetryObservability(grpc._observability.ObservabilityPlugin):
             _LOGGER.exception("Initiate observability failed with: %s", e)
 
         grpc._observability.observability_init(self)
-        return self
 
-    def __exit__(self, exc_type, exc_val, exc_tb) -> None:
-        self.exit()
-
-    def exit(self) -> None:
+    def observability_deinit(self) -> None:
         # Sleep so we don't loss any data. If we shutdown export thread
         # immediately after exit, it's possible that core didn't call RecordEnd
         # in callTracer, and all data recorded by calling RecordEnd will be
@@ -150,3 +169,29 @@ class OpenTelemetryObservability(grpc._observability.ObservabilityPlugin):
         _cyobservability._record_rpc_latency(
             self.exporter, method, target, rpc_latency, status_code
         )
+
+
+def _start_open_telemetry_observability(
+    otel_o11y: OpenTelemetryObservability,
+) -> None:
+    global _OPEN_TELEMETRY_OBSERVABILITY  # pylint: disable=global-statement
+    with _observability_lock:
+        if _OPEN_TELEMETRY_OBSERVABILITY is None:
+            _OPEN_TELEMETRY_OBSERVABILITY = otel_o11y
+            _OPEN_TELEMETRY_OBSERVABILITY.observability_init()
+        else:
+            raise RuntimeError(
+                "gPRC Python observability was already initialized!"
+            )
+
+
+def _end_open_telemetry_observability() -> None:
+    global _OPEN_TELEMETRY_OBSERVABILITY  # pylint: disable=global-statement
+    with _observability_lock:
+        if not _OPEN_TELEMETRY_OBSERVABILITY:
+            raise RuntimeError(
+                "Trying to end gPRC Python observability without initialize first!"
+            )
+        else:
+            _OPEN_TELEMETRY_OBSERVABILITY.observability_deinit()
+            _OPEN_TELEMETRY_OBSERVABILITY = None

src/python/grpcio_tests/tests/observability/_observability_api_test.py

@@ -24,6 +24,8 @@ class AllTest(unittest.TestCase):
         expected_observability_code_elements = (
             "OpenTelemetryObservability",
             "OpenTelemetryPlugin",
+            "start_open_telemetry_observability",
+            "end_open_telemetry_observability",
         )
 
         self.assertCountEqual(

src/python/grpcio_tests/tests/observability/_open_telemetry_observability_test.py

@@ -20,6 +20,7 @@ import sys
 import time
 from typing import Any, Callable, Dict, List, Optional, Set
 import unittest
+from unittest.mock import patch
 
 import grpc
 import grpc_observability
@@ -134,7 +135,7 @@ class OpenTelemetryObservabilityTest(unittest.TestCase):
         if self._server:
             self._server.stop(0)
 
-    def testRecordUnaryUnary(self):
+    def testRecordUnaryUnaryUseContextManager(self):
         otel_plugin = BaseTestOpenTelemetryPlugin(self._provider)
         with grpc_observability.OpenTelemetryObservability(
             plugins=[otel_plugin]
@@ -146,6 +147,78 @@ class OpenTelemetryObservabilityTest(unittest.TestCase):
         self._validate_metrics_exist(self.all_metrics)
         self._validate_all_metrics_names(self.all_metrics)
 
+    def testRecordUnaryUnaryUseGlobalInit(self):
+        otel_plugin = BaseTestOpenTelemetryPlugin(self._provider)
+
+        grpc_observability.start_open_telemetry_observability(
+            plugins=[otel_plugin]
+        )
+        server, port = _test_server.start_server()
+        self._server = server
+        _test_server.unary_unary_call(port=port)
+
+        self._validate_metrics_exist(self.all_metrics)
+        self._validate_all_metrics_names(self.all_metrics)
+        grpc_observability.end_open_telemetry_observability()
+
+    def testCallGlobalInitThrowErrorWhenGlobalCalled(self):
+        grpc_observability.start_open_telemetry_observability(plugins=[])
+        try:
+            grpc_observability.start_open_telemetry_observability(plugins=[])
+        except RuntimeError as exp:
+            self.assertIn(
+                "gPRC Python observability was already initialized", str(exp)
+            )
+
+        grpc_observability.end_open_telemetry_observability()
+
+    def testCallGlobalInitThrowErrorWhenContextManagerCalled(self):
+        with grpc_observability.OpenTelemetryObservability(plugins=[]):
+            try:
+                grpc_observability.start_open_telemetry_observability(
+                    plugins=[]
+                )
+            except RuntimeError as exp:
+                self.assertIn(
+                    "gPRC Python observability was already initialized",
+                    str(exp),
+                )
+
+    def testCallContextManagerThrowErrorWhenGlobalInitCalled(self):
+        grpc_observability.start_open_telemetry_observability(plugins=[])
+        try:
+            with grpc_observability.OpenTelemetryObservability(plugins=[]):
+                pass
+        except RuntimeError as exp:
+            self.assertIn(
+                "gPRC Python observability was already initialized", str(exp)
+            )
+        grpc_observability.end_open_telemetry_observability()
+
+    def testContextManagerThrowErrorWhenContextManagerCalled(self):
+        with grpc_observability.OpenTelemetryObservability(plugins=[]):
+            try:
+                with grpc_observability.OpenTelemetryObservability(plugins=[]):
+                    pass
+            except RuntimeError as exp:
+                self.assertIn(
+                    "gPRC Python observability was already initialized",
+                    str(exp),
+                )
+
+    def testNoErrorCallGlobalInitThenContextManager(self):
+        grpc_observability.start_open_telemetry_observability(plugins=[])
+        grpc_observability.end_open_telemetry_observability()
+
+        with grpc_observability.OpenTelemetryObservability(plugins=[]):
+            pass
+
+    def testNoErrorCallContextManagerThenGlobalInit(self):
+        with grpc_observability.OpenTelemetryObservability(plugins=[]):
+            pass
+        grpc_observability.start_open_telemetry_observability(plugins=[])
+        grpc_observability.end_open_telemetry_observability()
+
     def testRecordUnaryUnaryWithClientInterceptor(self):
         interceptor = _ClientUnaryUnaryInterceptor()
         otel_plugin = BaseTestOpenTelemetryPlugin(self._provider)
@@ -212,7 +285,7 @@ class OpenTelemetryObservabilityTest(unittest.TestCase):
         self._validate_metrics_exist(self.all_metrics)
         self._validate_all_metrics_names(self.all_metrics)
 
-    def testNoRecordAfterExit(self):
+    def testNoRecordAfterExitUseContextManager(self):
         otel_plugin = BaseTestOpenTelemetryPlugin(self._provider)
         with grpc_observability.OpenTelemetryObservability(
             plugins=[otel_plugin]
@@ -230,6 +303,26 @@ class OpenTelemetryObservabilityTest(unittest.TestCase):
         with self.assertRaisesRegex(AssertionError, "No metrics was exported"):
             self._validate_metrics_exist(self.all_metrics)
 
+    def testNoRecordAfterExitUseGlobal(self):
+        otel_plugin = BaseTestOpenTelemetryPlugin(self._provider)
+
+        grpc_observability.start_open_telemetry_observability(
+            plugins=[otel_plugin]
+        )
+        server, port = _test_server.start_server()
+        self._server = server
+        self._port = port
+        _test_server.unary_unary_call(port=port)
+        grpc_observability.end_open_telemetry_observability()
+
+        self._validate_metrics_exist(self.all_metrics)
+        self._validate_all_metrics_names(self.all_metrics)
+
+        self.all_metrics = defaultdict(list)
+        _test_server.unary_unary_call(port=self._port)
+        with self.assertRaisesRegex(AssertionError, "No metrics was exported"):
+            self._validate_metrics_exist(self.all_metrics)
+
     def testRecordUnaryStream(self):
         otel_plugin = BaseTestOpenTelemetryPlugin(self._provider)
 
@@ -342,7 +435,7 @@ class OpenTelemetryObservabilityTest(unittest.TestCase):
         message: Optional[Callable[[], str]] = None,
     ) -> None:
         message = message or (lambda: "Proposition did not evaluate to true")
-        timeout = timeout or datetime.timedelta(seconds=10)
+        timeout = timeout or datetime.timedelta(seconds=5)
         end = datetime.datetime.now() + timeout
         while datetime.datetime.now() < end:
             if predicate():