FOSSMEC Docker Workshop Project

This repository is the hands-on project used in the Docker workshop.

The project is intentionally simple:

• Frontend: HTML, CSS and JavaScript
• Backend: Node.js + Express
• Database: MongoDB
• Database UI: Mongo Express
• Orchestration: Docker Compose

The application is a small registration demo. Participants enter a mock name, email and password, the browser sends the data to the Express backend, and the backend stores it in MongoDB.

The workshop also uses Mongo Express so participants can see the database directly, create databases and collections, and add documents themselves.

Important: Use fake data only. Do not enter a real password. This is a Docker teaching project, not a production authentication system.

What participants will see

Browser
   │
   │  http://localhost:5000
   ▼
Node.js + Express
   │
   │  Docker network: app-network
   ▼
MongoDB

Mongo Express
   │
   │  http://localhost:8080
   ▼
MongoDB

The browser-facing app runs on port 5000. Mongo Express runs on port 8080 on the host and connects to MongoDB over the Docker network.

Mongo Express login:

• Username: admin
• Password: pass

No local Node dependencies are required

Participants do not need to run npm install on their computer.

The Dockerfile installs the Node dependencies inside the image while the image is being built. The workshop therefore uses Docker to provide the application environment.

You only need Docker Desktop running. Git and VS Code are useful for working with the repository, but Node packages do not need to be installed on the host machine.

Repository layout

.
├── manual/
│   ├── README.md
│   └── backend/
│       ├── Dockerfile
│       ├── package.json
│       ├── server.js
│       └── public/
│
├── compose/
│   ├── README.md
│   ├── compose.yaml
│   └── backend/
│       ├── Dockerfile
│       ├── package.json
│       ├── server.js
│       └── public/
│
├── CHEATSHEET.md
└── INSTRUCTOR_GUIDE.md

There is deliberately no starter folder and no debugging exercise folder. The project is meant to be run with Docker from the beginning.

Recommended workshop flow

Part 1: Manual Docker setup

Use manual/README.md.

Participants will:

1. Create a Docker network.
2. Run MongoDB in a container.
3. Run Mongo Express in another container.
4. Use Mongo Express to create a database, collection and document.
5. Build the Node/Express application image with a Dockerfile.
6. Run the application container on the same Docker network.
7. Open the app at http://localhost:5000.
8. Submit mock registration data.
9. Refresh Mongo Express and see the document in MongoDB.
10. Preview Docker volumes as the Day 2 persistence topic.

Part 2: Docker Compose

Use compose/README.md.

Participants will replace the multiple docker run commands with one Compose file and run:

docker compose up --build

Then they can use:

• App: http://localhost:5000
• Mongo Express: http://localhost:8080

Cleaning everything up

Manual setup:

docker rm -f fossmec-backend mongo-express mongo

docker network rm app-network

This Day 1 project has no named MongoDB volume, so there is no volume cleanup step.

Compose setup:

docker compose down

Troubleshooting checklist

docker: command not found or Docker is not responding

Make sure Docker Desktop is open and running.

The app does not open on port 5000

Check the container:

docker ps

Then check its logs:

docker logs fossmec-backend

For Compose:

docker compose ps
docker compose logs app

The app says it cannot connect to MongoDB

Inside Docker, the MongoDB hostname is the container/service name, not localhost.

Manual setup uses:

MONGO_HOST=mongo

Compose uses the service name:

mongo

localhost inside the backend container means the backend container itself.

Mongo Express does not open on port 8080

Check that the container is running:

docker ps

Then inspect its logs:

docker logs mongo-express

For Compose:

docker compose logs mongo-express

Why is MongoDB not published to a host port?

It does not need one for this project. MongoDB and the other containers communicate over their Docker network. Only the browser-facing services need host ports published.

Workshop reminder

The important lesson is not the registration application itself. The application exists to give you something real to put inside containers and connect together while learning:

images → containers → ports → environment variables → networks → Dockerfiles → Compose

Volumes and persistence are intentionally left for Day 2.