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Lessons (35)

• API Gateway, BFF & Service Discovery

  … one front door for many services](/img/microservices/api-gateway.svg) Without vs with a gateway mermaid flowchart …

• VPC Endpoints, Transit Gateway and Hybrid Networking

  … S3 gateway endpoint for VPCs that access S3. ECR image pulls can also require ECR API and registry …

• API Contracts, Gateways and Security

  Make APIs evolvable and safe with explicit formats, versioning, idempotency, gateway policy, authentication and authorization. The problem in …

• Serverless: Lambda and API Gateway

  … A function that waits forever wastes money and makes failures harder to understand. API Gateway API Gateway receives …

• Design a Chat Application

  … text Sender app - WebSocket gateway - message API - conversation database - MessageAccepted event - online recipient gateway - offline push worker The …

• Cluster Networking, DNS and NetworkPolicies

  … public-gateway }] hostnames: ["shop.example.com"] rules: - matches: [{ path: { type: PathPrefix, value: /api } }] backendRefs: - { name: shop-api, port …

• VPC Networking Without the Confusion

  … Check its default route, NAT gateway placement, internet-gateway route from the NAT's public subnet, and outbound …

• Backend Design Scenarios

  … goes down? Put enforcement at the edge or API gateway for coarse protection, then add a service-level …

• Resilience Patterns

  … Without it, one slow service causes a cascading failure : mermaid flowchart LR U[👥 Users] -- G[Gateway] -- O[Orders …

• Which Pattern Do I Need?

  … Pub/Sub, Kafka topics, event-driven architecture Facade API Gateway, Backend for Frontend Proxy Reverse proxy, CDN, service …

• AWS Interview Questions: Clear Answers

  … Event retry behavior depends on the caller; API Gateway does not automatically retry Lambda invocations. Example: a customer …

• How a Web Request Works

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

• Practical Project: Deploy a Real CRM App on EKS

  … The VPC Link is AVAILABLE (if using API Gateway). 5. The API Gateway route points at the right …

• Multi-Account Strategy, Governance and Security Operations

  … Transit Gateway, shared egress and inspection. - Workload accounts : per team, per environment (dev, staging, prod). AWS Organizations and …

• Serverless Architecture

  … static frontend"] U -- APIG[API Gateway] APIG -- Auth["🔐 Cognito / Auth0"] APIG -- L1["λ orders API"] L1 -- DDB[(DynamoDB …

• Onion Architecture & Clean vs Hexagonal vs Onion

  … infrastructure, UI, tests Implementations of the interfaces, web framework, DB, external APIs SqlOrderRepository , controllers, EF Core / Prisma mermaid …

• Observability: Logs, Metrics & Traces

  … GET /checkout (total 820 ms) dateFormat x axisFormat %L section api-gateway gateway :0, 820 section orders-svc …

• NestJS Core Concepts

  … PAYMENT GATEWAY", useClass: process.env.NODE ENV === "test" ? FakeGateway : StripeGateway }, { provide: "APP NAME", useValue: "shop-api" }, { provide: "REDIS …

• Cross-Service Data: How to Join Without a Database JOIN

  … API composition The caller, API gateway or backend-for-frontend calls both services and joins the responses in …

• System Design Interview Framework

  … estimate peak traffic, define APIs and data keys, and draw one send/read path. Spend the deep dive …

• Proxies, APIs and Real-Time Protocols

  … Use request/response APIs for creating orders, with explicit errors and idempotency. Internal RPC can give typed contracts …

• Timeouts, Retries & Backpressure

  … Do not give every hop its own 1,000 ms timeout. Step Budget When it expires --- ---: --- Gateway/app …

• KISS: Keep It Simple, Stupid

  … Complex["❌ 3 users, day one"] direction LR GW[API Gateway] -- MS1[User service] & MS2[Auth service] & MS3[Profile …

• Capacity Planning, SLOs and Error Budgets

  … checkout API Question Clear answer --- --- How fast? 99% of POST /checkout requests finish in under 800 ms. How …

• Clean Architecture

  … new SendGridEmailSender(apiKey), }); app.post("/users", userController(registerUser)); Why bother? Testing becomes trivial Because the use case only …

• Monolith vs Microservices

  … many deployables"] direction LR GW[API Gateway] -- US[Users svc] -- UDB[(users DB)] GW -- OS[Orders svc] -- ODB …

• Deploying & Operating Microservices

  CI/CD per service, blue-green and canary releases, feature flags, API versioning, distributed tracing and the production …

• Data in Microservices: Sagas & the Outbox Pattern

  … Options: Approach How Trade-off --- --- --- API composition A BFF/gateway calls each service and joins in memory Simple …

• AWS Security Building Blocks

  … Use a maintained JWT verification library or a properly configured API Gateway authorizer. Base64-decoding the payload only …

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

  … Redux store between components, an event bus, an API gateway, an orchestrator in a microservice saga. --- 5. Memento …

• C4 Architecture Diagrams: Context, Container, Component and Code

  … For this API, a useful component diagram answers: “When checkout happens, which parts of the API collaborate?” mermaid …

• Structural Patterns: How to Connect Objects

  … balance = 50 ✅ You've used it: Vue 3 reactivity (built on Proxy ), MobX, API gateways, CDNs (a caching …

• EC2, Storage and Auto Scaling

  … Use a public subnet with an internet-gateway route and assign a public IPv4 address for this temporary …

• AWS: Start Here

  … The frontend sends POST /orders to an API. 3. The API validates the request and saves the order …

• Clean Architecture in Depth

  … interfaces 🔵 Interface adapters Controllers, presenters, gateways, repositories: convert data between formats APIs, UI or storage formats change Use …