3.3. Incident & Event Response

Every production system will eventually fail — the question is how quickly you detect, respond, and recover. This section covers the complete incident response lifecycle: capturing events from AWS services, automating response actions, managing fleet operations, and diagnosing root causes.

What breaks when incident response is ad-hoc? Time. Without automated detection, an engineer manually spots the problem 20 minutes after it starts. Without runbooks, the investigation takes another 30 minutes of "where do I look?" Without automated remediation, the fix requires manual intervention that could have been scripted. Each gap multiplies your total incident duration.

Think of incident response like a hospital emergency room. The ER doesn't wait for patients to describe their symptoms — triage nurses assess severity immediately, protocols route patients to specialists, and critical cases trigger automatic alerts to surgical teams. Your AWS environment needs the same: Health API events triggering EventBridge rules, Lambda functions isolating compromised instances, Step Functions orchestrating multi-step recovery procedures.

Consider the trade-off between automated and manual response. Automatic isolation of a "compromised" instance sounds great — until GuardDuty triggers a false positive and your automation takes down a production server. The balance is severity-based: automate high-confidence, high-severity responses (known crypto-mining patterns), but require human approval for ambiguous or lower-severity findings. How do you build that judgment into automation? Through careful EventBridge rule design and Step Functions approval workflows.