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Lessons (40)

• REST vs GraphQL vs gRPC

  … Not meant for customers.  REST: resources over HTTP …

• REST API Design

  … Once you've ordered one thing, you can guess how to order anything. REST (Representational State Transfer) organises …

• Scaling & Health Probes

  … DB reachable, caches warm Startup Has a slow app finished starting? Other probes wait; restarts only after the …

• Storage Engines & Database Operations

  … Keep independent backups, define retention, encrypt them, and test restoring a realistic dataset into an isolated environment. Know …

• Proxies, APIs and Real-Time Protocols

  Pick REST, RPC, queues, long polling, WebSockets, TCP or UDP based on the interaction shape. ![Communication choices: reverse …

• ConfigMaps, Secrets & Storage

  … Protect Secrets properly: Do Why --- --- Enable encryption at rest for etcd Secrets are stored encrypted Restrict access with …

• Hexagonal Architecture (Ports & Adapters)

  … The application core sits in the middle; everything else (web UI, REST API, tests, database, email, message queues …

• Behavioral Patterns II: Chain, Template, Iterator, Mediator, Memento, Visitor

  … this. cursor }); } // memento restore(memento) { ({ content: this. content, cursor: this. cursor } = memento); } get content() { return this. content; } } const …

• Helm, kubectl Cheat Sheet & Best Practices

  … reviewed, versioned, self-healing deploys. - Secure with RBAC (least privilege), a restrictive securityContext , NetworkPolicies and a secret manager …

• Pods

  … 80 bash kubectl apply -f pod.yaml kubectl get pods NAME READY STATUS RESTARTS AGE hello 1/1 …

• Next.js Rendering: CSR, SSR, SSG, ISR & Server Components

  … the restaurant hands you raw ingredients and a recipe (an empty HTML page + JavaScript). You cook at your …

• Why Kubernetes?

  … it decides where each container runs, restarts the ones that crash, scales them up and down, and rolls …

• Releases, Observability and Production Safety

  … Protect traffic with TLS, encrypt sensitive data at rest, rotate secrets, use least-privilege RBAC, and audit sensitive …

• Kubernetes Cluster Architecture

  … Every command ( kubectl , controllers, nodes) goes through its REST API. Validates and stores objects Head office reception etcd …

• Service Communication: Sync vs Async

  … request/response One service calls another (HTTP/REST or gRPC) and waits for the answer. mermaid sequenceDiagram participant …

• Services & Ingress

  … gone after restart" P1[pod] end subgraph With["✅ Through a Service"] C2[checkout] -- "http://shop-api" S{{"Service …

• Resilience Patterns

  … a network blip, a pod restarting. Retrying often helps, but retrying immediately and all at once can finish …

• Timeouts, Retries & Backpressure

  … storm. The big idea A queue is a restaurant waiting area. When it is full, taking more names …

• Debug Latency Like an Investigator

  … morning Batch reports, backup, cache expiry, scheduled work. Restart helps briefly Warm cache, leak, churn, periodic trigger. Safe …

• Transactions, Indexes & Concurrency

  … or both. It is not a backup: deletion and corruption replicate too. Restore-tested independent backups remain necessary.

• Structural Patterns: How to Connect Objects

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

• Delivery Guarantees: At-Most, At-Least & Exactly Once

  … C- C: process… 💥 crash Note over K,C: restart from offset 8 → message 7 is LOST Use for …

• Layered (N-Tier) Architecture

  … s the right choice. The big idea A restaurant has clear layers : the waiters talk to customers, the …

• Message Queues & RabbitMQ

  … true }); // survives broker restart channel.sendToQueue( "emails", Buffer.from(JSON.stringify({ to: "ana@mail.com", template: "welcome" })), { persistent …

• API Gateway, BFF & Service Discovery

  … Guests don't wander the corridors looking for housekeeping, the restaurant or the spa; they ask at the …

• Database Relations & Foreign Keys

  … that validation. Delete behavior is a product decision RESTRICT blocks deleting a customer with history. CASCADE removes true …

• S — Single Responsibility Principle

  … split them apart. The big idea In a restaurant, the chef cooks, the waiter serves and the cashier …

• Which Pattern Do I Need?

  … Memento stores snapshots to restore. Composite vs Decorator Both wrap objects. Composite groups many children ; Decorator wraps exactly …

• Linked Lists

  … leftovers return dummy.next; } Common mistakes - Losing the rest of the list: always save current.next before changing …

• How a Web Request Works

  … Charging a card twice… is not idempotent! (See REST API Design .) Status codes by family Range Meaning Common …

• How Browsers Render a Page

  … 600 run JS :crit, a3, 600, 750 parse rest :a4, 750, 1000 section defer parse HTML :b1, 0 …

• Code Smells & Refactoring

  … when you wear the refactoring hat you only restructure. Switch hats often, but never wear both at once …

• Brokers, Replication & Durability

  … B1 restarts, catches up as a follower Only replicas in the ISR can become leader, so the new …

• Deployments, ReplicaSets & Rollouts

  … 02:00 jobTemplate: spec: backoffLimit: 3 template: spec: restartPolicy: OnFailure containers: - name: report image: registry.example.com/reports …

• JavaScript Essentials: Event Loop, Closures & this

  … the rest of loadUser runs later as a microtask Part 2: Closures The big idea A function is …

• Docker & Containers

  … When you have dozens of containers across many machines and need auto-restarts, scaling and zero-downtime deploys …

• Topics, Partitions & Offsets

  … Compacted topics are great for restoring state (Kafka itself stores consumer offsets in a compacted topic, consumer offsets …

• Consumers & Consumer Groups

  … instance.id ) avoids rebalances when a pod simply restarts. Consumer lag: the key health metric Lag = latest offset …

• MVC, MVP & MVVM

  … the ViewModel role. - They're presentation patterns; combine them with Clean/Hexagonal for the rest of the app.

• Creational Patterns: How to Make Objects

  … Creational patterns hide the "how" of creating objects , so the rest of the code only asks for what …