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Lessons (40)

• Design a Logging and Monitoring Platform

  … During an outage, debug logging increases tenfold and the search cluster falls behind. What must be true Keep …

• CloudWatch: Know What Your App Is Doing

  Use logs, metrics, alarms, and audit records to discover a problem before users have to report it. The …

• Observability: Logs, Metrics & Traces

  … Logs, the "why" A log is a timestamped record of an event. Write structured logs (JSON), not free …

• MVC, MVP & MVVM

  Three patterns for separating what the user sees from the data and logic behind it. How each works …

• Sorting Algorithms

  … beating n log n Comparison sorts can't beat O(n log n). But if values are small …

• JavaScript Essentials: Event Loop, Closures & this

  … run all microtasks, then one task The famous quiz js console.log("1"); setTimeout(() = console.log("2"), 0 …

• Big-O Notation Made Simple

  … O(1), O(log n), O(n), O(n log n), O(n²). The steepest curve explodes fastest …

• Authentication, Authorization & API Security

  … Click "Log in with Google" App- U: redirect to Google (+ PKCE challenge) U- G: log in + consent G …

• A WhatsApp OTP Is Only Single Use If You Make It So

  … 3. Create the login in the same step (same transaction) whenever you can. If you cannot, record the …

• Multi-Account Strategy, Governance and Security Operations

  … billing and Organizations only; no workloads. - Log archive : immutable, centralized CloudTrail and Config logs. - Security tooling : GuardDuty, Security …

• What Is Apache Kafka?

  Kafka is a distributed, durable log of events that many systems can write to and read from at …

• Observability and Incident Response

  Use logs, metrics and traces together to find a real production failure and recover with evidence. The problem …

• Heaps & Priority Queues

  … Swap with the smaller child"] -- c c -- No e["✅ Return saved min"] The tree's height is log …

• DSA Interview Patterns Cheat Sheet

  … O(1) O(n) O(log n) O(log n) \ O(1) at the end · \ \ when you already …

• Run Containers on AWS with ECR and ECS

  … Create a task definition with CPU, memory, log configuration, and a task role. 3. Create an ECS service …

• Collaborative Document Editing & Real-Time Sync

  … converge concurrent and offline edits with a fenced per-document sequencer, a durable op log, CRDT merge and …

• Frontend Testing Strategy

  … pure logic Best for pure functions: formatters, calculations, validation, reducers. ts // cart.ts export function cartTotal(items: { price …

• Async JavaScript: Promises, async/await and Node's Event Loop

  … promise microtasks"] end js setTimeout(() = console.log("timeout"), 0); setImmediate(() = console.log("immediate")); Promise.resolve().then(() = console.log …

• Structural Patterns: How to Connect Objects

  … Date.now() }); } } const logger = new WinstonAdapter(winston); // the rest of the app is unchanged logger.log("info", "Server …

• VPC Endpoints, Transit Gateway and Hybrid Networking

  … Query logs in S3 with Athena or in CloudWatch Logs Insights. Reachability Analyzer traces a path between two …

• Pods: Where Your App Actually Runs

  … a log collector reading shared log files. Init container: a short setup task that must finish before the …

• Go Web Services with Gin

  … 60 time.Second, } go func() { if err := srv.ListenAndServe(); err != nil && !errors.Is(err, http.ErrServerClosed) { log.Fatalf …

• Troubleshooting Playbook

  … read Events] C -- D[kubectl logs: what did the app say?] D -- E[Check Service, endpoints, DNS, policies …

• Node.js and Express

  … routing, the middleware pipeline, validation, async error handling, project structure, configuration, security, rate limiting, logging and graceful shutdown …

• D — Dependency Inversion Principle

  High-level business logic should depend on abstractions, not on concrete details like databases or email providers. The …

• NestJS Core Concepts

  … every feature is a module , HTTP lives in controllers , business logic in providers , and a built-in dependency …

• Kafka vs RabbitMQ & the Kafka Ecosystem

  … RabbitMQ routes and deletes; Kafka stores an ordered log you can replay](/img/kafka/kafka-vs-rabbit.svg …

• Layered (N-Tier) Architecture

  … Keep most layers closed, or the separation quickly erodes. Layers vs tiers - Layers are a logical split of …

• StatefulSets, DaemonSets, Jobs and CronJobs

  … metadata: name: log-agent spec: selector: matchLabels: { app: log-agent } template: metadata: labels: { app: log-agent } spec: tolerations …

• Choosing an Architecture

  … a modular monolith along DDD bounded contexts , Hexagonal/Clean where logic is rich, simpler slices where it isn …

• Cost Optimization and the Well-Architected Framework

  … S3 data left in Standard forever, old log groups, over-provisioned IOPS. 5. Logging : CloudWatch Logs ingestion is …

• JavaScript Language Fundamentals

  … log(a); // 5 const user = { name: "Ana" }; const same = user; // copies the reference same.name = "Bo"; console.log …

• Docker & Containers

  … docker run -d -p 3000:3000 --name api -e DATABASE URL=postgres://… shop-api:1.0 docker logs …

• Creational Patterns: How to Make Objects

  … 2 }); console.log(tank.describe()); // Tank: ❤️ 400, 🏃 2 📘 JavaScript itself is prototype-based : every object links to a …

• Your Practical Kubernetes Workflow

  … describe pod <pod-name -n team-shop kubectl logs <pod-name --previous -n team-shop kubectl get events …

• API Contracts, Gateways and Security

  … Apply per-identity limits and avoid recording credentials or sensitive payloads in logs. Walk through a failure and …

• Clean Error Handling

  … logged, then forgotten; the caller thinks it worked try { await saveOrder(order); } catch (e) { console.log(e); } js …

• Practical Project: Deploy a Real CRM App on EKS

  … Observability What How --- --- Container logs CloudWatch Observability add-on or Fluent Bit → CloudWatch Logs, with a retention period …

• AWS: Start Here

  … Install AWS CLI v2, then configure a named profile: bash aws configure sso --profile academy aws sso login …

• Storage Engines & Database Operations

  Understand B-trees, LSM trees, write-ahead logs, connection pools, backups and the signals behind database reliability. What …