Ensure we don't brake bi-directional propagation if child powertools logger is passed as source_logger

Author: Michal Ploski

aws_lambda_powertools/logging/utils.py

@@ -36,10 +36,14 @@ def copy_config_to_registered_loggers(
     # 4. Only exclude set? Ignore Logger in the excluding list
 
     # Exclude source and powertools package logger by default
+    # If source logger is a child ensure we exclude parent logger to not break child logger
+    # from receiving/pushing updates to keys being added/removed
+    source_logger_name = source_logger.name.split(".")[0] if source_logger.child else source_logger.name
+
     if exclude:
-        exclude.update(source_logger.name, PACKAGE_LOGGER)
+        exclude.update(source_logger_name, PACKAGE_LOGGER)
     else:
-        exclude = {source_logger.name, PACKAGE_LOGGER}
+        exclude = {source_logger_name, PACKAGE_LOGGER}
 
     # Prepare loggers set
     if include:

tests/functional/test_logger_utils.py

@@ -195,6 +195,37 @@ def test_copy_config_to_ext_loggers_should_not_break_append_keys(stdout, log_lev
     powertools_logger.append_keys(key="value")
 
 
+def test_copy_child_config_to_ext_loggers_should_not_break_append_keys(stdout):
+    # GIVEN powertools logger AND  child initialized AND
+
+    # GIVEN Loggers are initialized
+    # create child logger before parent to mimick
+    # importing logger from another module/file
+    # as loggers are created in global scope
+    service = service_name()
+    child = Logger(stream=stdout, service=service, child=True)
+    parent = Logger(stream=stdout, service=service)
+
+    # WHEN a child Logger adds an additional key AND child logger adds additional key
+    # AND configuration copied from powertools child logger
+    # AND powertools logger and child logger used
+    child.structure_logs(append=True, customer_id="value")
+    parent.structure_logs(append=True, user_id="value")
+    utils.copy_config_to_registered_loggers(source_logger=child)
+    parent.warning("Logger message")
+    child.warning("Child logger message")
+
+    # THEN both custom keys should be propagated bi-directionally in parent and child loggers
+    # as parent logger won't be touched when config is being copied
+    parent_log, child_log = capture_multiple_logging_statements_output(stdout)
+    assert "customer_id" in parent_log
+    assert "customer_id" in child_log
+    assert "user_id" in parent_log
+    assert "user_id" in child_log
+    assert "Child Logger message" not in parent_log
+    assert child.parent.name == service
+
+
 def test_copy_config_to_parent_loggers_only(stdout):
     # GIVEN Powertools Logger and Child Logger are initialized
     # and Powertools Logger config is copied over