This content originally appeared on DEV Community and was authored by Stanley Amaziro
What is Docker? 
Docker is like a shipping container for your app. Just like how shipping containers can hold anything (TVs, clothes, food) and be shipped anywhere in the world, Docker containers hold your entire application and can run anywhere
The Problem Docker Solves
Without Docker:
“It works on my computer but not on the server.”
Need to install Node.js, MongoDB, and Redis separately
Different versions cause conflicts
Hard to set up for new developers
With Docker:
Everything works the same everywhere
One command starts everything
No installation conflicts
New developers set up in minutes
Think of it this way: Instead of installing Node.js, MongoDB, and Redis on your computer, Docker creates isolated “boxes” (containers) that already have everything installed. You just run one command, and all three boxes start working together!
Use Docker in 3 easy steps
1⃣ docker-compose up -d (start)
2⃣ docker-compose logs -f backend (check logs)
3⃣ docker-compose down (stop)
Understanding the Docker Files
Dockerfile
What it is: Recipe for building your backend app container
It tells Docker:
Start with Node.js 18
Copy your code into the container
Install dependencies (npm install)
Build TypeScript (npm run build)
Start the server on port 5000
docker-compose.yml
What it is: Orchestrates multiple containers (Backend, MongoDB, Redis)
It defines:
3 services: backend, MongoDB, Redis
How do they connect
What ports to expose
Environment variables (.env file)
Data storage (volumes)
.dockerignore
What it is: Tells Docker what NOT to copy into the container
Ignores:
node_modules (will be reinstalled)
.env (for security)
.git (not needed in container)
logs (will be created fresh)
This content originally appeared on DEV Community and was authored by Stanley Amaziro