🛠️ Lab 4 — Serverless Image Resizer

Type: Build-on-your-own Time: ~75 minutes Difficulty: Intermediate Cost: Free (Lambda + S3 free tier)

🎯 What you’ll build

Drop an image into an S3 bucket and watch a Lambda function automatically resize it into a thumbnail. No servers, no SSH, no Nginx. This is what serverless really feels like.

📋 Prerequisites

  • Comfortable with the AWS Console
  • Basic Python (you’ll edit a Lambda function — provided starter code)
  • An IAM user (not just root) for cleaner permission management

🛠️ AWS Services used

  • S3 — image storage + event trigger
  • Lambda — Python runtime that handles the resize logic
  • CloudWatch Logs — for debugging
  • IAM Roles — Lambda’s execution permissions
  • Pillow Lambda Layer — Python image library, attached as a layer

📖 The full walkthrough

Open Week2_Lab4_Lambda_Resizer.html in your browser. It’s a complete step-by-step guide with screenshots, code snippets, and inline hints.

💡 The HTML file is self-contained — no install, no internet needed once you’ve cloned the repo. Just double-click to open in your browser.

🆘 If you get stuck

  1. Re-read the relevant step in the HTML walkthrough
  2. Check the Common Mistakes callouts (red boxes in the walkthrough)
  3. Expand the 💡 Hint sections for guidance
  4. WhatsApp the group with a screenshot of the error
  5. Tag your post with #week2done

🎓 Submission

  1. Screenshot of an original image + the resized thumbnail in S3 (side by side)
  2. Screenshot of your CloudWatch Logs showing the Lambda invocation

⬅️ Back to Week 2