What caused the sudden 30% increase in API errors for Fabric (BPS)'s inventory management service yesterday?

Introduction

The sudden 30% increase in API errors for Fabric (BPS)'s inventory management service yesterday is a critical issue that demands immediate attention and thorough analysis. To address this problem, I'll employ a systematic approach to identify, validate, and resolve the root cause while considering both short-term fixes and long-term implications for our product ecosystem.

Step 1

Clarifying Questions (3 minutes)

• Given the abrupt nature of the increase, I'm wondering about recent changes. Have there been any deployments or updates to the inventory management service in the past 48 hours?

Why it matters: Recent changes often correlate with sudden performance issues. Expected answer: Yes, a minor update was deployed yesterday morning. Impact on approach: If confirmed, we'd focus on the recent deployment as a primary suspect.

• Considering the scale of the issue, I'm curious about its distribution. Is this 30% increase uniform across all API endpoints, or are specific endpoints more affected?

Why it matters: Helps narrow down the problem area and potential causes. Expected answer: The errors are concentrated in the stock update and query endpoints. Impact on approach: We'd prioritize investigating these specific endpoints and their dependencies.

• Thinking about potential external factors, has there been any unusual spike in traffic or user activity that might explain this increase?

Why it matters: Distinguishes between internal issues and external pressures. Expected answer: No significant traffic anomalies observed. Impact on approach: We'd focus more on internal system issues rather than capacity problems.

• Reflecting on the broader system, are other services that interact with the inventory management API experiencing any related issues or increased latency?

Why it matters: Helps determine if this is an isolated issue or part of a larger system problem. Expected answer: Some latency increases in related services, but no other major issues reported. Impact on approach: We'd investigate potential cascading effects and interdependencies between services.