CheatCoders

SSRF Hardening in Node: Block Metadata and DNS Rebinding on Fetches

Block link-local addresses, cloud metadata IPs, and DNS rebinding when Node services fetch user-supplied URLs, closing classic SSRF paths in user content flows. Production checklist included.

Debugging System Design

Distributed Deadlock Detection: Cycles Across Postgres Rows and Redis Locks

Trace lock ordering that spans Postgres rows and Redis locks, then break cycles with timeouts and consistent global ordering across both systems. Production checklist included.

AWS Debugging

CloudWatch Logs Anomaly Detection: Ignore Deploy Noise, Catch Novel Errors

Tune CloudWatch Logs anomaly detection to ignore expected deploy log shape changes while still catching novel error signatures that indicate real regressions. Production checklist included.

Debugging Node.js

Node Core Dump Analysis: Symbolicate Native Crashes Inside Containers

Enable controlled core dumps in ECS, symbolicate Node native crashes, and scrub dumps before sharing so segfault hunts do not leak customer data. Production checklist included.

AWS System Design

API Gateway WebSocket Fan-Out: Coalesce Pushes After Reconnect Storms

Buffer and coalesce WebSocket pushes through API Gateway so reconnect storms after brief blips do not melt backends with thundering-herd fan-out. Production checklist included.

AWS Machine Learning System Design

Feature Stores vs Inline Compute: Real-Time Decisions Without Training Skew

Choose online feature stores versus compute-on-read for real-time decisions based on latency, freshness, and training-serving skew risk in ML inference paths. Production checklist included.

AWS Debugging Node.js

X-Ray Service Maps Lie: Fix Missing Spans in Node Trace Edges

Correct missing spans from undici, AWS SDK v3, and Lambda quirks so X-Ray service maps stop misleading on-call engineers during incident triage. Production checklist included.

System Design

Exactly-Once Illusions: Design At-Least-Once Plus Truly Idempotent Handlers

Design for at-least-once delivery with idempotent consumers and stop chasing broker exactly-once myths that fail under realistic failure and replay conditions. Production checklist included.

AWS System Design

SLA Error Budgets: Drive Automated Load Shedding Before Hard Outages

Tie load shedding and feature flags to error budgets so reliability degrades gracefully under overload instead of hard-failing every customer simultaneously. Production checklist included.

Node.js System Design

Consistent Hashing for WebSockets: Sticky Gateways During Scale Events

Route WebSocket sessions with consistent hashing and graceful migration so sticky gateway affinity survives scale-out and scale-in without dropping active clients. Production checklist included.