🔐 Building SteganoVault: A Production-Grade Steganography Tool with Docker, Flask, MySQL, and Nginx

I built SteganoVault, a full-stack steganography platform that can hide secret messages inside images, text files, PDFs, DOCX documents, audio, and video. The application runs as a 4-container Docker Compose architecture using Flask, Gunicorn, MySQL, Nginx, and phpMyAdmin. Along the way, I worked with Docker networking, health checks, persistent volumes, reverse proxy configuration, Git, Docker Hub, image optimization, authentication, file processing, and frontend debugging. The interesting part was not just building the application. The interesting part was debugging it. I faced 18 real issues, including package compatibility problems, port conflicts, broken frontend files, browser caching, MySQL health-check failures, Docker Hub upload failures, IPv6 networking problems, OpenCV download failures, multi-stage Docker problems, health-check loops, and a 1.97 GB Docker image that I eventually reduced to 847 MB. This article documents the complete journey.