🐳 Docker Lab: "Build Your Own Service"

This lab is designed to help you get familiar with Docker and Docker Compose by creating very simple services.
Each student will add their own service into a shared docker-compose.yml.

At the end of the lab, we will have 10 services running together, each one showing the student’s name and exposing a health endpoint.

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🎯 Objectives

• Learn the basics of creating Docker images and services.
• Practice adding services into a docker-compose.yml file.
• Work together as a team, following a trunk-based development approach.
• Test and verify that all services are running correctly.

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📂 Project Structure

docker-lab/
├─ docker-compose.yml       # All services defined here
├─ README.md
├─ test.sh                  # Script to test all services
└─ services/
   └─ student01/            # Each student creates their own folder
      ├─ Dockerfile
      └─ app/

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🔌 Ports

Each student has a dedicated port. Inside the container, all services use port 8080, but on the host, you will use:

• Student01 → 8101
• Student02 → 8102
• ...
• Student10 → 8110

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📝 Service Requirements

• Must expose port 8080 inside the container.
• Must respond on:
  • / → with your name.
  • /health → with text ok.

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🚀 Service Options

You can choose one of the following templates:

1) BusyBox (Static HTML)

Dockerfile

FROM busybox:stable
WORKDIR /srv
RUN printf "Hello, I am Student01 👋\n" > index.html  && printf "ok\n" > health
EXPOSE 8080
CMD ["sh", "-c", "httpd -f -p 8080 -h /srv"]

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2) Python Flask

app/app.py

from flask import Flask
app = Flask(__name__)

@app.get("/")
def index():
    return "Hello, I am Student01 👋"

@app.get("/health")
def health():
    return "ok"

Dockerfile

FROM python:3.11-slim
WORKDIR /app
RUN pip install flask
COPY app/ /app/
EXPOSE 8080
CMD ["python", "-m", "flask", "--app", "app:app", "run", "--host=0.0.0.0", "--port=8080"]

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3) Node.js Express

app/server.js

const express = require("express");
const app = express();
app.get("/", (_, res) => res.send("Hello, I am Student01 👋"));
app.get("/health", (_, res) => res.send("ok"));
app.listen(8080, () => console.log("listening on 8080"));

Dockerfile

FROM node:20-alpine
WORKDIR /app
COPY app/ /app/
RUN npm init -y && npm install express
EXPOSE 8080
CMD ["node", "server.js"]

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🤝 Collaboration: Trunk-Based Development

We will follow a trunk-based workflow:

1. Everyone uses main branch (main or trunk) as the single source of truth.
2. Create a short-lived branch for your service:

   git checkout -b student01-service

3. Add your service folder under services/ and edit docker-compose.yml.
4. Commit and push:

   git add .
   git commit -m "Add student01 service"
   git push origin student01-service

5. Open a Pull Request (PR) to merge into main.
6. Another student must review and approve your PR before merging.
7. After merge, everyone pulls the latest trunk:

   git checkout main
   git pull origin main

👉 This way, all students practice integration and avoid merge conflicts.

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✅ Testing All Services

Run all containers:

docker compose up --build -d

Run the test script:

./test.sh

Expected output:

✅ port 8101: health ok
✅ port 8102: health ok
...

Open your service in the browser:

• http://localhost:810X/
• http://localhost:810X/health

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📋 Acceptance Criteria

• Service builds successfully.
• / → responds with your name.
• /health → responds with ok.
• Correct port mapping (810X).
• Short README inside your folder with your name and how to run the service.

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⏱ Suggested Timeline

• 10 min → setup & explanation.
• 40 min → students create their services.
• 20 min → integrate code (PRs, reviews).
• 15 min → run tests together and demo.

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🏆 End Result

By the end of the lab, you will have a multi-service Docker Compose project where each service belongs to a student, running together in one environment.