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Michelle
Michelle

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30-Day Cloud & DevOps Challenge: Day 2 — Building My First Backend API

#api #backend #devjournal #node

The journey continues! After setting up my project structure on Day 1, today was all about building the heart of my microservices platform: the backend API.

If you missed Day 1, you can catch up here: [https://dev.to/michellewanjiru/day-1-of-my-30-day-cloud-devops-challenge-project-setup-2a5a?trk=public_post_comment-text]

What I Set Out to Do Today

Build a working REST API that can:

  • Respond to HTTP requests
  • Return JSON data
  • Serve as the foundation for my microservices platform

Simple, right? Well... let me share how it actually went.

The Tech Stack I Chose

I decided to go with Node.js + Express for my backend because:

  • JavaScript is everywhere (frontend, backend, even DevOps tools)
  • Express is lightweight and beginner-friendly
  • I already had Node.js installed on my Ubuntu system

Step-by-Step: What I Actually Did

1. Initial Setup 

cd backend
npm init -y  # Creates package.json
npm install express  # Web framework
npm install --save-dev nodemon  # Auto-restarts server on changes
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What I learned: package.json is like a shopping list for your project. Every tool you add gets listed there, making it easy to share your project with others.

2. Writing My First Server

I created server.js with three endpoints:

const express = require('express');
const app = express();
const PORT = 8000;

// Root endpoint
app.get('/', (req, res) => {
    res.json({ message: 'Welcome to the Microservices Platform API', status: 'running' });
});

// Health check endpoint
app.get('/health', (req, res) => {
    res.json({ status: 'healthy', service: 'backend-api', timestamp: new Date().toISOString() });
});

// Users endpoint (mock data for now)
app.get('/users', (req, res) => {
    res.json([
        { id: 1, name: 'Alice', email: 'alice@example.com' },
        { id: 2, name: 'Bob', email: 'bob@example.com' },
        { id: 3, name: 'Charlie', email: 'charlie@example.com' }
    ]);
});

app.listen(PORT, () => {
    console.log(` Server running on http://localhost:${PORT}`);
});
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Understanding each part:

  • app.get() defines what happens when someone visits a URL
  • (req, res) => {} is a function that handles the request and sends a response
  • res.json() sends data back as JSON (the language of APIs)

3. The Challenge That Almost Stopped Me

I tried running my server with:

npm run dev
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And got this error:

npm error Missing script: "dev"
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My reaction: 😅 Wait, what? I thought I had this!

How I diagnosed it:

npm run  # Shows all available scripts
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Only test was showing. I had completely forgotten to add the "dev" script to my package.json!

The fix: I opened package.json and added:

"scripts": {
    "start": "node server.js",
    "dev": "nodemon server.js"
}
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Lesson learned: Never assume your configuration is correct. Always verify with simple commands.

4. The Moment It Finally Worked

After fixing the script, I ran:

npm run dev
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And saw:

 Server running on http://localhost:8000
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Then in another terminal:

curl http://localhost:8000/
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Response:

{"message":"Welcome to the Microservices Platform API","status":"running"}
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I literally cheered in my chair.🎉 My first API was alive!

Testing All Endpoints

Here's what each endpoint returned:

Endpoint Response
GET / Welcome message
GET /health Service status with timestamp
GET /users List of 3 mock users

All working perfectly!

Key Learnings from Day 2

Technical Concepts I Gained:

  1. HTTP Methods: GET is how you retrieve data from a server
  2. JSON: The universal language of APIs — both request and response
  3. Ports: Think of them like doors — 8000 is the door my API listens on
  4. Endpoints: Specific URLs that do specific things (/health, /users)
  5. Package.json scripts: Custom commands to automate repetitive tasks

Problem-Solving Skills:

  • Diagnosing errors: npm run helped me see what was actually available
  • Reading error messages: "Missing script" told me exactly what was wrong
  • Step-by-step verification: Test each piece before assuming everything works

Mindset Shifts:

  • Done is better than perfect: My first API doesn't have a database yet, and that's okay
  • Celebrate small wins: Getting that first curl response was genuinely exciting
  • Embrace mistakes: The missing script error taught me more than if everything worked perfectly

Tips for Anyone Starting Their Own API

  1. Start simple. My API only does 3 things right now — that's enough!
  2. Test as you go. Don't write 100 lines of code before testing. Test after each endpoint.
  3. Use curl or browser. It's satisfying to see your API respond in real-time.
  4. Save your package.json changes. I almost forgot this one!
  5. Keep notes. Document what you learn, especially the mistakes.

A Quick Thank You

To everyone following along and the community helping me debug, your support means everything. Special shoutout to those who reminded me to check my package.json scripts!

What's Next (Day 3)

Tomorrow, I'm building a frontend that will:

  • Fetch data from my API
  • Display the list of users
  • Show the health status

It's going to be the first time my frontend and backend talk to each other!

Links & Resources

Let's Connect!

Are you also learning backend development? Building your first API? I'd love to hear about your journey!

Drop a comment below or connect with me on LinkedIn at https://www.linkedin.com/in/michelle-wanjiru-420877275/?lipi=urn%3Ali%3Apage%3Ad_flagship3_detail_base%3BHw%2F74ryNQ7CjXqDkL3k7eQ%3D%3D. Let's learn together!

This is Day 2 of my 30-Day Cloud & DevOps Challenge. Follow along as I build a complete microservices platform from scratch!

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