Describe a method for implementing feature flags in a Flask application.
Instruction: Explain how to use feature flags to toggle features in a Flask application dynamically.
Context: This question assesses the candidate's ability to implement advanced application functionality controls such as feature toggling, which allows for safer deployments and A/B testing.
Updated
Official answer available
Read the opening below, then unlock the full answer and practical guidance.
A feature flag selects behavior from a controlled configuration source. Loading a JSON file once at startup creates a static snapshot; changing that file or an environment variable does not automatically update every running worker.
For live changes, choose a provider or shared store with an explicit refresh/version policy and bounded caching. Define the fallback when the provider is unavailable and audit who can change a flag. A kill switch needs a known propagation delay, not a claim of instant global effect...