AWS Lambda File Upload

A lightweight, serverless AWS Lambda function for uploading files directly to Amazon S3 with CloudFront signed URL generation. This project provides a simple and efficient solution for handling file uploads in serverless architectures.

🎯 Motivation

File uploads are a common requirement in modern web applications, but implementing a secure, scalable solution can be complex. This project was created to:

• Simplify file uploads: Provide a ready-to-use Lambda function that handles file uploads without the need for complex server infrastructure
• Leverage serverless architecture: Take advantage of AWS Lambda's scalability and cost-effectiveness for handling file uploads
• Generate secure URLs: Automatically create CloudFront signed URLs for secure file access
• Reduce boilerplate: Save development time by providing a production-ready solution that can be easily integrated into existing projects

Whether you're building a new application or need to add file upload functionality to an existing one, this project offers a straightforward, maintainable solution that follows AWS best practices.

✨ Features

• 📤 Direct S3 Upload: Upload files directly to Amazon S3 buckets
• 🔒 Secure Access: Generate CloudFront signed URLs for secure file access
• 🚀 Serverless: Built on AWS Lambda for automatic scaling and cost efficiency
• 📝 Multipart Support: Handles multipart/form-data file uploads
• ⚡ Lightweight: Minimal dependencies and fast execution
• 🔧 Configurable: Easy configuration through environment variables

📋 Prerequisites

Before using this Lambda function, ensure you have:

• An AWS account with appropriate permissions
• An S3 bucket configured for file storage
• A CloudFront distribution (optional, for signed URLs)
• AWS Lambda runtime environment (Node.js 18.x or later recommended)
• AWS credentials with permissions for:
  • S3: PutObject, PutObjectAcl
  • CloudFront: Access to generate signed URLs (if using CloudFront)

🚀 Installation

1. Clone this repository:

git clone https://github.com/yourusername/aws-lambda-file-upload.git
cd aws-lambda-file-upload

2. Install dependencies:

npm install

⚙️ Configuration

Configure the Lambda function using environment variables:

Variable	Description	Required
REACT_APP_ACCESS_KEY_ID	AWS Access Key ID	Yes
REACT_APP_SECRET_ACCESS_KEY	AWS Secret Access Key	Yes
REACT_APP_S3_BUCKET_NAME	Name of the S3 bucket	Yes
REACT_APP_CLOUDFRONT_ACCESS_KEY_ID	CloudFront Key Pair ID	Yes (if using CloudFront)
REACT_APP_CLOUDFRONT_PRIVATE_KEY_STRING	CloudFront Private Key (base64 encoded)	Yes (if using CloudFront)
REACT_APP_CLOUD_FRONT_ORIGIN_PATH	CloudFront distribution URL	Yes (if using CloudFront)

Setting Environment Variables in AWS Lambda

1. Go to your Lambda function in the AWS Console
2. Navigate to Configuration → Environment variables
3. Add the required variables listed above

📖 Usage

Lambda Function Handler

The function expects an event with the following structure:

{
  headers: {
    'content-type': 'multipart/form-data; boundary=...'
  },
  body: 'base64-encoded-file-data'
}

Example Request

// Example using fetch API
const formData = new FormData();
formData.append('file', fileInput.files[0]);

const response = await fetch('your-api-gateway-endpoint', {
  method: 'POST',
  body: formData
});

const result = await response.json();
console.log('File URL:', result);

Response

The function returns a CloudFront signed URL:

"https://your-cloudfront-domain.com/1234567890"

🔧 Deployment

Using AWS CLI

1. Package your function:

zip -r function.zip index.js node_modules/

2. Deploy to Lambda:

aws lambda update-function-code \
  --function-name your-function-name \
  --zip-file fileb://function.zip

Using Serverless Framework

# serverless.yml
service: aws-lambda-file-upload

provider:
  name: aws
  runtime: nodejs18.x
  environment:
    REACT_APP_ACCESS_KEY_ID: ${env:AWS_ACCESS_KEY_ID}
    REACT_APP_SECRET_ACCESS_KEY: ${env:AWS_SECRET_ACCESS_KEY}
    REACT_APP_S3_BUCKET_NAME: ${env:S3_BUCKET_NAME}
    # ... other environment variables

functions:
  upload:
    handler: index.handler
    events:
      - http:
          path: upload
          method: post

📝 API Reference

handler(event)

Main Lambda handler function that processes file uploads.

Parameters:

• event (Object): Lambda event object containing:
  • headers (Object): Request headers with content-type
  • body (String): Base64-encoded file data

Returns:

• Promise<String>: CloudFront signed URL of the uploaded file

Throws:

• Error if S3 upload fails
• Error if file extraction fails

🤝 Contributing

Contributions are welcome! This project is open source and we encourage community participation.

How to Contribute

1. Fork the repository
2. Create a feature branch (git checkout -b feature/amazing-feature)
3. Commit your changes (git commit -m 'Add some amazing feature')
4. Push to the branch (git push origin feature/amazing-feature)
5. Open a Pull Request

Development Guidelines

• Follow existing code style and conventions
• Add comments for complex logic
• Update documentation for new features
• Ensure backward compatibility when possible
• Test your changes thoroughly

📄 License

This project is open source and available under the MIT License.

👤 Author

Developer

• Email: devpuffer0807@gmail.com
• Telegram: @devpuffer0807

🙏 Acknowledgments

• Built with AWS SDK
• Uses parse-multipart for multipart form parsing
• CloudFront URL signing powered by aws-cloudfront-sign

📚 Additional Resources

• AWS Lambda Documentation
• Amazon S3 Documentation
• CloudFront Documentation

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