Resilience

This guide walks you through auditing an application's resilience to third-party service failures.

The Goal: Graceful Degradation

When external services fail, the application should bend but not break. Users experience reduced functionality, not total outages.

• Fault-tolerant — app continues running when optional services are down
• Isolated — one failing dependency does not cascade to unrelated features
• Protected — all external calls wrapped in error handling (try/catch, timeouts, circuit breakers)
• Classified — dependencies categorized as critical vs optional with appropriate handling for each

Before You Start

1. Confirm you're in the target repository's root directory
2. Identify what external services the app depends on
3. Have Docker available to start/stop dependencies for testing
4. Have the user available for questions about critical vs optional services