Stop Overpaying for AWS WAF! (5 Cost Optimization Tips)
Source: Dev.to
Cost Optimization Tips for AWS WAF
As a Solution Architect deep‑diving into AWS WAF cost savings, I discovered that a lot of spend comes from “noise.”
If you’re working on the Cost Optimization pillar of the AWS Well‑Architected Framework, don’t overlook your Web Application Firewall. WAF costs can spiral if you treat it as a “set and forget” service. Below are practical ways to align AWS WAF with cost‑efficiency best practices.
1️⃣ Use “Scope‑Down” Statements 📉
Don’t run expensive rules (e.g., Bot Control or Regex patterns) on every request.
Use scope‑down statements to inspect only specific paths such as /login or /checkout. This reduces the volume of inspected traffic and directly lowers your bill.
2️⃣ Optimize Rule Order 🔢
AWS WAF evaluates rules in priority order.
Place cheap, high‑volume block rules (e.g., IP rate limits, Geo‑blocking) at the top so that noise is blocked early, preventing costly evaluations of more complex rules on junk traffic.
3️⃣ Leverage AWS Shield Advanced 🛡️
If your monthly WAF + Data Transfer bill exceeds roughly $3 k, consider switching to AWS Shield Advanced.
Shield Advanced provides a flat‑fee model and waives standard WAF WebACL and rule fees for protected resources.
4️⃣ Smart Logging 📝
Logging every request to CloudWatch Logs can become expensive quickly.
- Use Kinesis Data Firehose for high‑volume logs (cheaper ingestion).
- Filter logs to capture only “Blocked” requests or specific rule matches, reducing storage costs.
5️⃣ Separation of Concerns 🏗️
Avoid applying WAF to static assets (images, CSS) unless absolutely necessary.
Route static traffic through a separate CloudFront behavior that doesn’t invoke the WAF, or create rules that explicitly ignore those file extensions.
Pro Tip
Review “Unused Rules” quarterly. If a rule hasn’t triggered in the past 90 days, it’s likely just adding to your monthly rental fees—delete it.
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