Improve error handling and logging in event writers

[oto-macenauer-absa]

This pull request introduces significant improvements to error handling, writer result aggregation, and test coverage for the event gate Lambda. The main changes include standardizing error responses, updating all writer modules to return detailed error information, aggregating writer results in the main handler, and adding comprehensive unit tests to validate both successful and failure scenarios.

Error Handling and Response Standardization

• Introduced a centralized _error_response helper in event_gate_lambda.py to standardize all error responses, ensuring consistent structure and error details for authentication, authorization, validation, and internal errors. [1] [2] [3] [4]
• Updated all endpoints to use this helper for error cases, replacing ad-hoc or incomplete error responses. [1] [2] [3]

Writer Modules: Result Reporting

• Refactored writer_kafka, writer_eventbridge, and writer_postgres so their write functions now return a tuple (success: bool, error_message: str|None), allowing the main handler to report which writer failed and why. [1] [2] [3] [4] [5]
• Enhanced error logging and error message propagation in each writer for better observability and debugging. [1] [2] [3]

Main Handler Logic

• Updated the POST topic message flow to invoke all writers independently, aggregate their results, and return a 500 error with detailed error information if any writer fails, or a 202 success if all succeed.
• Improved topic schema and authorization checks to use consistent error responses. [1] [2]

Configuration and File Path Robustness

• Refactored configuration file loading to use absolute paths based on the project root, improving robustness when running from different working directories. [1] [2]

Testing and Coverage

• Added a comprehensive test suite in tests/test_event_gate_lambda.py that mocks external dependencies, covers all major GET and POST flows, and verifies correct error and success response structures across a variety of scenarios, including writer failures and internal errors.

These changes collectively make the Lambda handler more robust, easier to debug, and better tested, with clear and actionable error reporting throughout.

Related

Closes #52

Release notes:

• Improve error handling
• Improve logging in event writers

[miroslavpojer]

• fast read
• review on call