fix: append structured logs when injecting lambda context (#86)

* fix: append logs when injecting lambda context #85

* docs: update changelog

Signed-off-by: heitorlessa <lessa@amazon.co.uk>

* chore: bump version to 1.0.1

Signed-off-by: heitorlessa <lessa@amazon.co.uk>

Author: heitorlessa

CHANGELOG.md

@@ -6,6 +6,10 @@ and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0
 
 ## [Unreleased]
 
+## [1.0.1] - 2020-07-06
+### Fixed
+- **Logger**: Fix a bug with `inject_lambda_context` causing existing an Logger keys to be overriden if `structure_logs` was called before
+
 ## [1.0.0] - 2020-06-18
 ### Added
 - **Metrics**: `add_metadata` method to add any metric metadata you'd like to ease finding metric related data via CloudWatch Logs

aws_lambda_powertools/logging/logger.py

@@ -197,7 +197,7 @@ def decorate(event, context):
             lambda_context = build_lambda_context_model(context)
             cold_start = _is_cold_start()
 
-            self.structure_logs(cold_start=cold_start, **lambda_context.__dict__)
+            self.structure_logs(append=True, cold_start=cold_start, **lambda_context.__dict__)
             return lambda_handler(event, context)
 
         return decorate

pyproject.toml

@@ -1,6 +1,6 @@
 [tool.poetry]
 name = "aws_lambda_powertools"
-version = "1.0.0"
+version = "1.0.1"
 description = "Python utilities for AWS Lambda functions including but not limited to tracing, logging and custom metric"
 authors = ["Amazon Web Services"]
 classifiers=[

tests/functional/test_logger.py

@@ -256,3 +256,30 @@ def test_logger_invalid_sampling_rate():
     # THEN we should raise InvalidLoggerSamplingRateError
     with pytest.raises(InvalidLoggerSamplingRateError):
         Logger(sampling_rate="TEST")
+
+
+def test_inject_lambda_context_with_structured_log(lambda_context, stdout):
+    # GIVEN Logger is initialized
+    logger = Logger(stream=stdout)
+
+    # WHEN structure_logs has been used to add an additional key upfront
+    # and a lambda function is decorated with logger.inject_lambda_context
+    logger.structure_logs(append=True, additional_key="test")
+
+    @logger.inject_lambda_context
+    def handler(event, context):
+        logger.info("Hello")
+
+    handler({}, lambda_context)
+
+    # THEN lambda contextual info should always be in the logs
+    log = capture_logging_output(stdout)
+    expected_logger_context_keys = (
+        "function_name",
+        "function_memory_size",
+        "function_arn",
+        "function_request_id",
+        "additional_key",
+    )
+    for key in expected_logger_context_keys:
+        assert key in log