Build a Professional Real-Time Chat App with Docker, Flask, and Socket.IO

Source: Dev.to

Instant Messaging Made Simple: Meet ProChat

Building a real-time chat application is often seen as a “right of passage” for developers. It touches on many critical concepts: WebSockets, asynchronous events, database persistence, and containerization.

Today, I want to share ProChat (DockerChat), a project that takes this concept to the next level. It’s not just a “Hello World” chat app; it’s a fully functional, professional‑grade communication tool that you can spin up in seconds thanks to Docker.

Why This Project?

Most chat tutorials stop at “sending a message.” ProChat aims to be something you’d actually want to use. We focused on:

• Ease of Deployment – If you have Docker, you have the app. No requirements.txt hell, no database setup scripts.
• User Experience – A modern, dark‑themed UI that feels responsive and alive.
• Feature Completeness – Channels, private DMs, media support, and persistent history.

Key Features

Real‑Time Communication

Using Flask‑Socket.IO, messages are delivered instantly (< 100 ms latency). Whether you are in the same room or connecting over the internet, the chat flows naturally without refreshing the page.

Multi‑Channel & Private Messaging

Users can hop between topic‑based channels (e.g., general, tech, gaming) or slide into DMs for private 1‑on‑1 conversations. The UI clearly separates these contexts, keeping conversations organized.

Rich Media Support

Text is boring! ProChat supports:

• Emojis – A built‑in picker with 100+ emojis.
• Images & Videos – Drag, drop, and share media directly in the chat.
• Links – URLs are automatically detected and clickable.

Smart Persistence

We use SQLite with Docker volumes to ensure your data is safe. Restart the container? Your messages are still there. It’s the perfect balance of simplicity and reliability for a self‑hosted app.

The Tech Stack

• Backend: Python 3.11 with Flask 2.3.3
• Real‑Time Engine: Socket.IO with Eventlet for high‑concurrency handling
• Database: SQLAlchemy ORM with SQLite
• Frontend: Vanilla JS (ES6+), HTML5, and CSS3 – no heavy frameworks
• DevOps: Docker & Docker Compose for orchestration

Quick Start

1. Clone the repository (or download the files).

2. Run with Docker Compose:

   docker-compose up -d

3. Open your browser to http://localhost:5000.

That’s it! Open multiple tabs to simulate different users, or share your IP with a friend on the same network to chat instantly.

Why Docker?

Containerizing this application was a game‑changer. It ensures that:

• The expected Python version is used.
• Dependencies are isolated.
• The database file is preserved in a volume, separating code from data.
• User setup is reduced to a single command.

What’s Next?

Future updates might include:

• Redis for scaling across multiple nodes.
• User authentication integration.

Check out the code and let me know what you think!

Happy coding! 🚀

Repo