What caused the sudden spike in error rates for Apollo GraphQL's Federation Gateway service yesterday afternoon?

Introduction

The sudden spike in error rates for Apollo GraphQL's Federation Gateway service yesterday afternoon is a critical issue that demands immediate attention and thorough analysis. As we delve into this problem, we'll employ a systematic approach to identify, validate, and address the root cause while considering both short-term fixes and long-term implications for our product ecosystem.

Step 1

Clarifying Questions (3 minutes)

• Looking at the timing, I'm thinking this might be related to a recent deployment. Has there been any significant update to the Federation Gateway service in the past 24-48 hours?

Why it matters: Recent changes often correlate with sudden performance issues. Expected answer: Yes, there was a minor update to the service configuration. Impact on approach: If confirmed, we'd focus on rollback options and code review.

• Considering the nature of Federation Gateway, I'm wondering about traffic patterns. Have we seen any unusual spikes in query volume or complexity leading up to the error rate increase?

Why it matters: Unusual traffic can strain the system and expose vulnerabilities. Expected answer: Traffic has been within normal ranges. Impact on approach: If traffic is normal, we'd shift focus to internal system issues.

• Given the interconnected nature of GraphQL services, I'm curious about downstream dependencies. Have any related services reported issues or changes that might impact the Federation Gateway?

Why it matters: Issues in dependent services can propagate and manifest in the gateway. Expected answer: No reported issues from other services. Impact on approach: If confirmed, we'd investigate gateway-specific problems more closely.

• Thinking about system health, I'm interested in resource utilization. Have we observed any unusual patterns in CPU, memory, or network usage for the Federation Gateway servers?

Why it matters: Resource constraints can lead to increased error rates. Expected answer: Some servers showed higher than normal CPU usage. Impact on approach: This would guide us to investigate potential performance bottlenecks or resource allocation issues.