How-To Guides

Step-by-step scenario guides for solving various real-world problems. Each guide covers problem definition, required tools, core code, and common mistakes.

Computer Vision / Image Processing

OpenCV Pattern Matching

Implement template matching to automatically locate component positions on PCB boards

Python OCR Text Extraction

Extract text from scanned document images and digitize them

Web Development

JWT Token Authentication

Build an Access/Refresh Token-based authentication flow for SPAs

CSS Responsive Layout

Build mobile-to-desktop responsive layouts with Flexbox/Grid

React State Management

Compare useState/useReducer/Context and choose the optimal pattern

API Rate Limiting

Implement API rate limiting with Token Bucket algorithm and Redis

TypeScript Generic Patterns

Generic utility types, conditional types, and type guard patterns

GraphQL API Design

Design GraphQL APIs with Apollo Server, solve N+1, implement auth

WebSocket Real-Time Communication

Build real-time chat, notifications, and live dashboards with Socket.IO

DevOps / Infrastructure

Docker Log Analysis

How to quickly trace error causes from container logs

K8s Pod Troubleshooting

Debug pod failures like CrashLoopBackOff using kubectl

Nginx SSL Reverse Proxy

Set up an HTTPS reverse proxy with Let's Encrypt + Nginx

GitHub Actions CI/CD

Build test, Docker build, and deployment pipelines with GitHub Actions

SSL Certificate Setup

Issue Let's Encrypt wildcard SSL certificates with auto-renewal

Linux Performance Tuning

CPU/memory/disk/network bottleneck analysis and sysctl kernel tuning

Terraform Infrastructure Management

Codify and automate AWS cloud infrastructure with Terraform IaC

Prometheus + Grafana Monitoring

Build Prometheus metric collection and Grafana dashboards

Security

Nmap Port Scanning

Port scanning and vulnerability analysis for server security auditing

Networking

Wireshark Packet Analysis

Capture network traffic and diagnose TCP/HTTP issues

Embedded Systems

Arduino Sensor Serial Communication

Automatically collect DHT temperature/humidity sensor data with Python

Data / Automation

Excel to JSON API Integration

Clean Excel data with pandas and send it via REST API

Python Web Crawling

Automatically collect web data using requests + BeautifulSoup

Regex Data Extraction

Batch extract emails, phone numbers, and URLs using regular expressions

Python Data Analysis

Build data cleaning, aggregation, and visualization pipelines with Pandas/NumPy

Statistics

A/B Test Significance Testing

Statistical analysis of experiment results using chi-squared test and p-value

Database

SQL Query Optimization

Analyze slow query causes with EXPLAIN ANALYZE and tune indexes

MongoDB Aggregation Pipeline

Complex data analysis and transformation with MongoDB aggregation

Elasticsearch Search Engine

Build full-text search with Elasticsearch, text analysis, and autocomplete

Redis Caching Strategy

Cache-Aside, Write-Through patterns and Cache Stampede prevention

Developer Tools

Git Conflict Resolution

A practical guide to systematically resolving merge/rebase conflicts