🚀 Longest-Line-Detector-using-Google-Cloud-Functions

📘 Overview

This project implements a serverless Cloud Function that automatically processes text files uploaded to a Google Cloud Storage (GCS) bucket. This project implements a serverless Cloud Function that automatically processes text files uploaded to a Google Cloud Storage (GCS) bucket. Whenever a new .txt file is uploaded, the function:

Downloads the file temporarily to /tmp/.

Finds the longest line(s) in the file.

Saves those lines in a new output file named <original_filename>_longest.txt.

Uploads this result file back to the same GCS bucket.

The function ignores hidden files (.filename), non-text files (.pdf, .jpg, etc.), and result files ending with _longest.txt.

☁️ Key Concepts Used

| Component                       | Description                                                                                 | 
| Google Cloud Function (2nd Gen) | A serverless compute service that automatically scales in response to events.               | 
| Eventarc Trigger (GCS Event)    | Automatically invokes the function whenever a new file is created in the GCS bucket.        | 
| Cloud Storage                   | Used to store both input .txt files and output _longest.txt result files.                   | 
| Functions Framework             | Enables writing portable and trigger-based Python functions compatible with Cloud Functions.| 

Learning Objectives

• Understand how event-driven architectures work in GCP.

• Learn to handle Cloud Storage events with Cloud Functions.

• Implement file I/O operations in a secure, ephemeral environment (/tmp/).

• Use structured logging for debugging and observability.

• Design a clean, modular function using the functions_framework decorator.

🧩 Project Structure

📦 longest-line-detector
├── main.py              # Function source code
├── requirements.txt     # Dependencies
├── README.md            # Project documentation

⚙️ Deployment Steps (via GCP Console UI)

• Go to → Google Cloud Console → Cloud Functions .

• Click Create Function.

• Under Environment, select 2nd Gen.

• Name: longest-line-detector

• Trigger type: Eventarc trigger → Cloud Storage → Finalize/Create event (select your bucket, e.g. ibd-week3)

• Runtime: Python 3.10 or later

• Entry point: hello_gcs

• Source code: Inline editor

• Paste the above main.py code

• Add dependencies in requirements.txt:

google-cloud-storage
functions-framework

• Click Deploy and wait for confirmation.

🧪 Testing

• Upload a .txt file to the GCS bucket (e.g., sample.txt).

• Wait a few seconds for the function to trigger.

• You’ll see logs like: