Cloudflare in trouble

Summary

The video humorously recounts how Cloudflare, renowned for stopping massive DDoS attacks, accidentally took itself down due to a React coding mistake involving an infinite loop in a useEffect hook. This minor error triggered thousands of API calls, overwhelming their backend and causing a Thundering Herd problem during a forced reset. The narrator explains how the lack of rate limiting, slow rollouts, and proper pre-deployment checks contributed to the outage, while clarifying that this was a development oversight rather than a hacking incident. Despite the chaos, Cloudflare’s quick fixes and future Argo service promise greater resilience, offering both a cautionary tale and a tech learning moment.

Takeaways

• 😀 Cloudflare, known for defending against massive DDoS attacks, was taken down by a simple coding mistake in React.
• 😀 The issue was caused by a problematic `useEffect` hook in React, which created an infinite loop due to object comparison in the dependency array.
• 😀 The `useEffect` hook caused repeated backend calls, leading to 25,000 API calls in a short period, overloading the system.
• 😀 The problem arose because the object passed in the `useEffect` dependency array was constantly seen as 'different' due to shallow comparison.
• 😀 Cloudflare attempted to fix the issue by clearing logins, but this led to a 'Thundering Herd' problem, where too many requests came in at once.
• 😀 The underlying issue was a lack of proper rate-limiting on the API and failure to detect the problem before it went live.
• 😀 The situation highlights the importance of testing code thoroughly before releasing it into production, especially for high-traffic services.
• 😀 Despite the major issue, it was not a sophisticated attack or hack, but rather a basic mistake in React development.
• 😀 Cloudflare's reliance on its infrastructure to handle huge loads failed to prevent a small bug from taking down their service.
• 😀 The incident emphasizes the need for better monitoring, slow rollouts, and more proactive measures in detecting abnormal system behavior.
• 😀 Cloudflare plans to use its new Argo service for automatic rollbacks in the future, which could have prevented this issue if implemented sooner.

Q & A

What is the main issue Cloudflare faced in the video?

The main issue was a bug caused by an incorrect use of React's `useEffect` hook, which resulted in infinite API calls and system overload. This led to Cloudflare experiencing a failure despite being renowned for stopping large-scale DDoS attacks.

What is the `useEffect` hook in React, and why was it problematic in this case?

`useEffect` is a React hook used to run side effects in function components. It was problematic here because the hook’s dependency array contained an object that was not the same in memory on each render, causing the effect to trigger continuously, resulting in an infinite loop of API calls.

What is a 'Thundering Herd' problem, and how did it relate to Cloudflare's issue?

A 'Thundering Herd' problem occurs when many requests are made simultaneously after an event, like users needing to log in again after Cloudflare attempted to reset the system. This leads to overwhelming the system with too many requests at once, causing further crashes.

Why was this issue not caught during development or pre-production?

The issue was not caught because the code included a problematic object in the `useEffect` dependency array, and the large volume of requests wasn't flagged as an anomaly. There was also no gradual rollout or monitoring to catch the issue before full-scale deployment.

What role did the API's inability to handle load play in the failure?

The API’s inability to handle the load exacerbated the situation, as it lacked rate limiting and failed to recover from the volume of requests generated by the bug. This compounded the effect of the `useEffect` issue, leading to service downtime.

What is meant by the statement 'React wasn’t the problem here'?

The statement suggests that React itself was not at fault. The real problem was the improper use of `useEffect`, and more critically, the lack of safeguards in the API infrastructure, such as rate limiting and error recovery.

How could Cloudflare have avoided this issue in production?

Cloudflare could have avoided this issue by implementing a slow rollout of the new feature, monitoring for anomalies, and using automatic rollback systems, like their new Argo service, to revert changes as soon as problems were detected.

What does the speaker mean by 'meat and potatoes, gun, foot, bang'?

This phrase is a humorous and exaggerated way of saying the issue was a simple, avoidable mistake — akin to shooting oneself in the foot — rather than some complex attack or external hack.

What was Cloudflare’s response to the issue once it was identified?

Once Cloudflare identified the problem, they cleared everyone's login sessions to reset the system. However, this created a 'Thundering Herd' problem, where many users logged in simultaneously, causing the system to fail again.

What lesson does the speaker draw from this Cloudflare incident?

The speaker emphasizes that even the most experienced and robust companies can fall victim to simple, avoidable coding mistakes. The key takeaway is to catch issues early in development, conduct gradual rollouts, and implement safeguards to prevent such failures.