Only allow AzureLogHandler to be added once to each logger

.pre-commit-config.yaml

@@ -27,7 +27,6 @@ repos:
     rev: v8.16.1
     hooks:
       - id: gitleaks
-        args: ["--config", ".gitleaks.toml"]
   - repo: 'https://github.com/PyCQA/pydocstyle'
     rev: 6.3.0
     hooks:

status_function/run_tests.sh

@@ -34,6 +34,7 @@ echo "Running unit tests..."
 API_URL="http://some.api.url" \
 PRIVATE_KEY="-----BEGIN OPENSSH PRIVATE KEY-----mykey1234-----END OPENSSH PRIVATE KEY-----" \  # gitleaks:allow
 AZURE_TENANT_ID="00000000-0000-0000-0000-000000000000" \
+CENTRAL_LOGGING_CONNECTION_STRING="InstrumentationKey=00000000-0000-0000-0000-000000000000" \
 python -m coverage run \
   --omit=".venv/*","tests/*" \
   -m unittest discover \

status_function/status/logutils.py

@@ -54,6 +54,10 @@ def set_log_handler(name: str = "status") -> None:
     logger = logging.getLogger(name)
     log_settings = settings.get_settings()
     if log_settings.CENTRAL_LOGGING_CONNECTION_STRING:
+        for handler in logger.handlers:
+            if isinstance(handler, AzureLogHandler):
+                raise RuntimeError("AzureLogHandler already added to logger.")
+
         custom_dimensions = {"logger_name": f"logger_{name}"}
         handler = AzureLogHandler(
             connection_string=log_settings.CENTRAL_LOGGING_CONNECTION_STRING

status_function/tests/test_function_app.py

@@ -611,5 +611,13 @@ def test_bearer_auth(self):
             self.assertEqual("status-app", username)
 
 
+class TestLoggingUtils(TestCase):
+    def test_called_twice(self):
+        """Adding multiple loggers can cause large storage bills ££££."""
+        with self.assertRaises(RuntimeError):
+            status.logutils.set_log_handler("a")
+            status.logutils.set_log_handler("a")
+
+
 if __name__ == "__main__":
     main()