Add ProxyLoggerProvider, ProxyLogger and associated tests (#3575)

* 3060 adds ProxyLoggerProvider, ProxyLogger and associated tests

* Updates changelog for 3060 (add proxy classes for logging)

* Removes proxy classes from module level log import following review

* Moves changelog entry to unreleased

* Fixes build failures

* Fix mypy and lint

---------

CHANGELOG.md

@@ -27,6 +27,8 @@ and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0
   ([#3623](https://github.com/open-telemetry/opentelemetry-python/pull/3623))
 - Improve Resource Detector timeout messaging
   ([#3645](https://github.com/open-telemetry/opentelemetry-python/pull/3645))
+- Add Proxy classes for logging
+  ([#3575](https://github.com/open-telemetry/opentelemetry-python/pull/3575))
 
 ## Version 1.22.0/0.43b0 (2023-12-15)
 

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

@@ -112,6 +112,37 @@ def emit(self, record: "LogRecord") -> None:
         pass
 
 
+class ProxyLogger(Logger):
+    def __init__(  # pylint: disable=super-init-not-called
+        self,
+        name: str,
+        version: Optional[str] = None,
+        schema_url: Optional[str] = None,
+    ):
+        self._name = name
+        self._version = version
+        self._schema_url = schema_url
+        self._real_logger: Optional[Logger] = None
+        self._noop_logger = NoOpLogger(name)
+
+    @property
+    def _logger(self) -> Logger:
+        if self._real_logger:
+            return self._real_logger
+
+        if _LOGGER_PROVIDER:
+            self._real_logger = _LOGGER_PROVIDER.get_logger(
+                self._name,
+                self._version,
+                self._schema_url,
+            )
+            return self._real_logger
+        return self._noop_logger
+
+    def emit(self, record: LogRecord) -> None:
+        self._logger.emit(record)
+
+
 class LoggerProvider(ABC):
     """
     LoggerProvider is the entry point of the API. It provides access to Logger instances.
@@ -166,21 +197,37 @@ def get_logger(
         return NoOpLogger(name, version=version, schema_url=schema_url)
 
 
-# TODO: ProxyLoggerProvider
+class ProxyLoggerProvider(LoggerProvider):
+    def get_logger(
+        self,
+        name: str,
+        version: Optional[str] = None,
+        schema_url: Optional[str] = None,
+    ) -> Logger:
+        if _LOGGER_PROVIDER:
+            return _LOGGER_PROVIDER.get_logger(
+                name,
+                version=version,
+                schema_url=schema_url,
+            )
+        return ProxyLogger(
+            name,
+            version=version,
+            schema_url=schema_url,
+        )
 
 
 _LOGGER_PROVIDER_SET_ONCE = Once()
-_LOGGER_PROVIDER = None
+_LOGGER_PROVIDER: Optional[LoggerProvider] = None
+_PROXY_LOGGER_PROVIDER = ProxyLoggerProvider()
 
 
 def get_logger_provider() -> LoggerProvider:
     """Gets the current global :class:`~.LoggerProvider` object."""
-    global _LOGGER_PROVIDER  # pylint: disable=global-statement
+    global _LOGGER_PROVIDER  # pylint: disable=global-variable-not-assigned
     if _LOGGER_PROVIDER is None:
         if _OTEL_PYTHON_LOGGER_PROVIDER not in environ:
-            # TODO: return proxy
-            _LOGGER_PROVIDER = NoOpLoggerProvider()
-            return _LOGGER_PROVIDER
+            return _PROXY_LOGGER_PROVIDER
 
         logger_provider: LoggerProvider = _load_provider(  # type: ignore
             _OTEL_PYTHON_LOGGER_PROVIDER, "logger_provider"
@@ -194,7 +241,7 @@ def get_logger_provider() -> LoggerProvider:
 def _set_logger_provider(logger_provider: LoggerProvider, log: bool) -> None:
     def set_lp() -> None:
         global _LOGGER_PROVIDER  # pylint: disable=global-statement
-        _LOGGER_PROVIDER = logger_provider  # type: ignore
+        _LOGGER_PROVIDER = logger_provider
 
     did_set = _LOGGER_PROVIDER_SET_ONCE.do_once(set_lp)
 

opentelemetry-api/tests/logs/test_logger_provider.py

@@ -44,7 +44,7 @@ def test_get_logger_provider(self):
         assert logs_internal._LOGGER_PROVIDER is None
 
         assert isinstance(
-            get_logger_provider(), logs_internal.NoOpLoggerProvider
+            get_logger_provider(), logs_internal.ProxyLoggerProvider
         )
 
         logs_internal._LOGGER_PROVIDER = None

opentelemetry-api/tests/logs/test_proxy.py

@@ -0,0 +1,63 @@
+# Copyright The OpenTelemetry Authors
+#
+# Licensed under the Apache License, Version 2.0 (the "License");
+# you may not use this file except in compliance with the License.
+# You may obtain a copy of the License at
+#
+#     http://www.apache.org/licenses/LICENSE-2.0
+#
+# Unless required by applicable law or agreed to in writing, software
+# distributed under the License is distributed on an "AS IS" BASIS,
+# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+# See the License for the specific language governing permissions and
+# limitations under the License.
+
+# pylint: disable=W0212,W0222,W0221
+import typing
+import unittest
+
+import opentelemetry._logs._internal as _logs_internal
+from opentelemetry import _logs
+from opentelemetry.sdk._logs import LogRecord  # type: ignore
+from opentelemetry.test.globals_test import LoggingGlobalsTest
+
+
+class TestProvider(_logs.NoOpLoggerProvider):
+    def get_logger(
+        self,
+        name: str,
+        version: typing.Optional[str] = None,
+        schema_url: typing.Optional[str] = None,
+    ) -> _logs.Logger:
+        return TestLogger(name)
+
+
+class TestLogger(_logs.NoOpLogger):
+    def emit(self, *args, **kwargs):
+        return LogRecord(timestamp=0)
+
+
+class TestProxy(LoggingGlobalsTest, unittest.TestCase):
+    def test_proxy_logger(self):
+        provider = _logs.get_logger_provider()
+        # proxy provider
+        self.assertIsInstance(provider, _logs_internal.ProxyLoggerProvider)
+
+        # provider returns proxy logger
+        logger = provider.get_logger("proxy-test")
+        self.assertIsInstance(logger, _logs_internal.ProxyLogger)
+
+        # set a real provider
+        _logs.set_logger_provider(TestProvider())
+
+        # get_logger_provider() now returns the real provider
+        self.assertIsInstance(_logs.get_logger_provider(), TestProvider)
+
+        # logger provider now returns real instance
+        self.assertIsInstance(
+            _logs.get_logger_provider().get_logger("fresh"), TestLogger
+        )
+
+        # references to the old provider still work but return real logger now
+        real_logger = provider.get_logger("proxy-test")
+        self.assertIsInstance(real_logger, TestLogger)

tests/opentelemetry-test-utils/src/opentelemetry/test/globals_test.py

@@ -42,7 +42,7 @@ def reset_logging_globals() -> None:
     """WARNING: only use this for tests."""
     logging_api._LOGGER_PROVIDER_SET_ONCE = Once()  # type: ignore[attr-defined]
     logging_api._LOGGER_PROVIDER = None  # type: ignore[attr-defined]
-    # logging_api._PROXY_LOGGER_PROVIDER = _ProxyLoggerProvider()  # type: ignore[attr-defined]
+    logging_api._PROXY_LOGGER_PROVIDER = logging_api.ProxyLoggerProvider()  # type: ignore[attr-defined]
 
 
 class TraceGlobalsTest(unittest.TestCase):
@@ -73,3 +73,18 @@ def setUp(self) -> None:
     def tearDown(self) -> None:
         super().tearDown()
         reset_metrics_globals()
+
+
+class LoggingGlobalsTest(unittest.TestCase):
+    """Resets logging API globals in setUp/tearDown
+
+    Use as a base class or mixin for your test that modifies logging API globals.
+    """
+
+    def setUp(self) -> None:
+        super().setUp()
+        reset_logging_globals()
+
+    def tearDown(self) -> None:
+        super().tearDown()
+        reset_logging_globals()