Understanding Automation in Service Deployment
Automation in tech can feel like magic. It handles repetitive tasks without human intervention. But what happens when automation does exactly what it's told, without room for human error correction? Let's unpack this using a real-world example from Cloudflare and learn how to make automation not just faster but safer.
Step 1: The Goal of Automation
Cloudflare wanted to quickly update their Web Application Firewall (WAF) rules globally. Think of these rules as security measures that keep bad traffic out of websites.
What is a Web Application Firewall (WAF)?
A WAF is a security system that filters and monitors HTTP traffic to and from a web application. It's like a bouncer at a club, letting good guests in and keeping troublemakers out.
Their tool for this task was Quicksilver, meant to ensure these updates touched every edge of the network swiftly.
What is an Edge Network?
An Edge Network consists of multiple servers positioned worldwide, allowing content to be delivered from a location closest to the user. This improves speed and availability.
Step 2: The Breakdown
On July 2, 2019, a WAF rule (numbered 100173) was introduced to stop malicious attacks like XSS (cross-site scripting).
What is XSS?
XSS stands for Cross-Site Scripting, a type of security vulnerability that enables attackers to inject malicious scripts into content from otherwise trusted websites.
The rule leveraging PCRE (Perl Compatible Regular Expressions) had a critical flaw. It was overly complex, causing catastrophic backtracking under real-world usage.
What is Catastrophic Backtracking?
Catastrophic Backtracking happens when a regex pattern is inefficiently designed, leading to intense processor usage as it struggles to find a match. It's like looking for something in a disorderly room and checking each item multiple times.
Here’s a simple representation:
.*(?:.*=.*)When real traffic hit this pattern, it overloaded the CPU — akin to an unexpected rush-hour traffic jam.
Step 3: When Automation Multiplies Failure
Because the rule deployed as planned, it quickly spread the faulty pattern globally. This fast rollout was both the success and the issue — no slow rollout to catch the mistake early meant the CPU usage hit 100%, causing a massive slowdown.
What is CPU Usage?
CPU Usage measures how much processing power is being used. 100% indicates the processor is fully occupied, much like a conveyor belt moving at full speed with no room for more items.
Step 4: Fixing the Breakdown
To fix it, the faulty rule was immediately disabled:
WAF rule 100173: enabled = falsePreventative Measures
Cloudflare then revised their process:
- Performance Testing: Analyze the WAF rules for inefficiencies like backtracking before deployment.
- Staged Rollout: Introduce changes gradually, watching for issues on a smaller scale.
- Guardrails: Implement checks to prevent widespread failures.
Just as in driving, where speed bumps slow you down to keep you safe, these guardrails control deployment pace to reduce potential damage.
Step 5: The Lesson in Resilient Automation
The adjustment meant a slight delay in security deployment. Yet, it shifted the risk from runtime — when it's most damaging — to the testing phase, where it’s manageable.
Resilience is not just speed; it's controlled speed that prepares for failures.
The core lessons
- Fast isn't always best: Automation must prepare for failures, not just speed up processes.
- Safeguards are crucial: Testing and staged rollouts can prevent a small issue from becoming a massive problem.
- Expect the unexpected: Always design with an eye on what could go wrong and how to mitigate it.
Understanding these concepts ensures that automation isn't just about doing things quickly, but doing them wisely.