Add LoggerFactory for structured logging

Fix project-alvarium#10
Signed-off-by: Omar Eissa <[email protected]>

src/alvarium/streams/factories.py

@@ -1,3 +1,5 @@
+import logging
+import socket
 from .exceptions import StreamException
 from .mock import MockProvider
 from .mqtt import MQTTStreamProvider
@@ -12,4 +14,27 @@ def get_provider(self, info: StreamInfo):
         if info.type == StreamType.MQTT:
             return MQTTStreamProvider(info.config)
         else:
-            raise StreamException(f"{info.type} is not yet implemented.")
+            raise StreamException(f"{info.type} is not yet implemented.")
+
+class LoggerFactory:
+    """A factory that returns a specific implementation of a Logger"""
+
+    def get_logger(self, name: str = __name__, level: int = logging.DEBUG) -> logging.Logger:
+        class LowerCaseLevelNameFormatter(logging.Formatter):
+            def format(self, record):
+                record.levelname = record.levelname.lower()
+                return super().format(record)
+
+        logger = logging.getLogger(name)
+        logger.propagate = False
+        logging.basicConfig(level=level)
+
+        handler = logging.StreamHandler()
+        formatter = LowerCaseLevelNameFormatter('{"timestamp":"%(asctime)s","log-level": "%(levelname)s","message":"%(message)s","hostname":"%(hostname)s", "application":"%(filename)s", "line-number":"%(filename)s:%(lineno)d"}', 
+                                      datefmt='%Y-%m-%dT%H:%M:%SZ',
+                                      validate=True, 
+                                      defaults={'hostname': socket.gethostname()} )
+        handler.setFormatter(formatter)
+        logger.addHandler(handler)
+
+        return logger

tests/example/__main__.py

@@ -2,6 +2,8 @@
 import os
 import sys
 
+from alvarium.streams.factories import LoggerFactory
+
 PROJECT_PATH = os.getcwd()
 SOURCE_PATH = os.path.join(
     PROJECT_PATH,"src"
@@ -26,8 +28,7 @@
 sdk_info = SdkInfo.from_json(json.dumps(config["sdk"]))
 
 # construct logger
-logger = logging.getLogger(__name__)
-logging.basicConfig(level = logging.DEBUG)
+logger = LoggerFactory().get_logger(name=__name__, level=logging.DEBUG)
 
 # construct annotators
 annotator_factory = AnnotatorFactory()

tests/test_sdk.py

@@ -4,6 +4,7 @@
 from alvarium.annotators.factories import AnnotatorFactory
 from alvarium.sdk import Sdk
 from alvarium.default import DefaultSdk
+from alvarium.streams.factories import LoggerFactory
 
 class TestSdk(unittest.TestCase):
 
@@ -17,8 +18,7 @@ def test_default_sdk_instantiate_should_not_raise(self):
         annotator_factory = AnnotatorFactory()
         annotators = [annotator_factory.get_annotator(kind=annotation_type, sdk_info=sdk_info) for annotation_type in sdk_info.annotators]
 
-        logger = logging.getLogger(__name__)
-        logging.basicConfig(level = logging.DEBUG)
+        logger = LoggerFactory().get_logger(name=__name__, level=logging.DEBUG)
 
         sdk: Sdk = DefaultSdk(annotators=annotators,config=sdk_info,logger=logger)
         sdk.close()
@@ -28,8 +28,7 @@ def test_sdk_should_create(self):
         annotator_factory = AnnotatorFactory()
         annotators = [annotator_factory.get_annotator(kind=annotation_type, sdk_info=sdk_info) for annotation_type in sdk_info.annotators]
 
-        logger = logging.getLogger(__name__)
-        logging.basicConfig(level = logging.DEBUG)
+        logger = LoggerFactory().get_logger(name=__name__, level=logging.DEBUG)
         sdk = DefaultSdk(annotators=annotators, config=sdk_info, logger=logger)
 
         test_data = b'test'
@@ -41,8 +40,7 @@ def test_sdk_should_mutate(self):
         annotator_factory = AnnotatorFactory()
         annotators = [annotator_factory.get_annotator(kind=annotation_type, sdk_info=sdk_info) for annotation_type in sdk_info.annotators]
 
-        logger = logging.getLogger(__name__)
-        logging.basicConfig(level = logging.DEBUG)
+        logger = LoggerFactory().get_logger(name=__name__, level=logging.DEBUG)
         sdk = DefaultSdk(annotators=annotators, config=sdk_info, logger=logger)
 
         old_data = b'old data'
@@ -56,8 +54,7 @@ def test_sdk_should_transit(self) -> None:
         annotator_factory = AnnotatorFactory()
         annotators = [annotator_factory.get_annotator(kind=annotation_type, sdk_info=sdk_info) for annotation_type in sdk_info.annotators]
 
-        logger = logging.getLogger(__name__)
-        logging.basicConfig(level = logging.DEBUG)
+        logger = LoggerFactory().get_logger(name=__name__, level=logging.DEBUG)
         sdk = DefaultSdk(annotators=annotators, config=sdk_info, logger=logger)
 
         test_data = b'test'
@@ -69,8 +66,7 @@ def test_sdk_should_create_published_annotations(self) -> None:
         annotator_factory = AnnotatorFactory()
         annotators = [annotator_factory.get_annotator(kind=annotation_type, sdk_info=sdk_info) for annotation_type in sdk_info.annotators]
 
-        logger = logging.getLogger(__name__)
-        logging.basicConfig(level = logging.DEBUG)
+        logger = LoggerFactory().get_logger(name=__name__, level=logging.DEBUG)
 
         sdk = DefaultSdk(annotators=annotators, config=sdk_info, logger=logger)