What caused the sudden 30% increase in API errors for LaunchDarkly's SDKs across multiple client libraries last week?

Introduction

The sudden 30% increase in API errors for LaunchDarkly's SDKs across multiple client libraries last week is a critical issue that demands immediate attention and thorough analysis. This problem could significantly impact our customers' ability to leverage feature flags effectively, potentially leading to service disruptions and eroding trust in our platform. I'll approach this issue systematically, focusing on identifying the root cause, validating hypotheses, and developing both short-term fixes and long-term preventive measures.

Step 1

Clarifying Questions (3 minutes)

• Looking at the timing, I'm thinking this could be related to a recent SDK update. Have we rolled out any SDK updates across multiple client libraries recently?

Why it matters: Recent changes are often the culprit in sudden performance shifts. Expected answer: Yes, we deployed a minor update last week. Impact on approach: If true, we'd focus on the changes in that update.

• Considering the scale of the issue, I'm wondering about our infrastructure. Have we seen any unusual patterns in our server logs or monitoring systems?

Why it matters: Infrastructure issues could explain widespread problems across SDKs. Expected answer: There were some anomalies in server response times. Impact on approach: This would shift our focus to backend systems and network issues.

• Given the multi-library nature of the problem, I'm curious about our testing processes. Did we run our full suite of integration tests before the last deployment?

Why it matters: Inadequate testing could have missed cross-library compatibility issues. Expected answer: Some tests were skipped due to time constraints. Impact on approach: We'd need to review and enhance our testing protocols.

• Thinking about external factors, have we seen any significant changes in usage patterns or load from our customers?

Why it matters: Unexpected load could strain our systems and cause errors. Expected answer: There's been a 20% increase in API calls from a major customer. Impact on approach: We'd need to investigate capacity planning and load balancing.