How to implement file upload functionality with Edge Functions

This guide demonstrates how to implement secure file upload functionality using Azion Edge Functions and Edge Storage. By handling file uploads at the edge, you can provide faster upload speeds and better user experience while maintaining security and scalability.

Requirements

Before you begin, ensure you have:

An Azion account
Azion CLI installed and configured
Node.js version 18 or higher
pnpm package manager installed
Basic understanding of JavaScript and Edge Functions
Edge Storage enabled in your Azion account

Getting started

Step 1: Set up your development environment

Clone the file upload example repository:

git clone https://github.com/egermano/edge-functions-examples.git
cd edge-functions-examples/packages/file-upload

Install the project dependencies:

pnpm install

Review the project structure to understand the implementation:

ls -la

You should see the main files including the Edge Function implementation, configuration files, and example upload forms.

Step 2: Configure environment variables

Create a .env file based on the example:

cp .env.example .env

Edit the .env file to include your storage configuration:

# Storage configuration
STORAGE_BUCKET_NAME=your-upload-bucket
MAX_FILE_SIZE=10485760  # 10MB in bytes
ALLOWED_FILE_TYPES=jpg,jpeg,png,gif,pdf,txt,doc,docx

Step 3: Create storage bucket

Create a bucket to store uploaded files:

azion create bucket your-upload-bucket

Replace your-upload-bucket with your preferred bucket name.

Step 4: Build the project

Compile your Edge Function for deployment:

pnpm build

This command builds your Edge Function and prepares it for deployment to Azion’s edge network.

Step 5: Test locally

Before deploying, test your file upload function locally:

pnpm dev

This starts a local development server where you can test file upload functionality.

Deploying to Azion

Step 1: Authenticate with Azion

azion login

Follow the authentication prompts to connect your CLI with your Azion account.

Step 2: Deploy the Edge Function

Deploy your file upload application to Azion’s edge network:

azion deploy

The deployment process will:

Upload your Edge Function code
Configure the edge application
Set up the necessary routing rules
Configure storage permissions
Provide you with a unique domain

Step 3: Configure storage permissions

Access Azion Console > Edge Storage
Select your storage bucket
Configure appropriate permissions for your Edge Function to read/write files

Step 4: Access your application

After deployment, you’ll receive a domain like https://xxxxxxx.map.azionedge.net. Your file upload application will be available at this URL within a few minutes after DNS propagation.

Understanding the implementation

File upload process

The file upload Edge Function typically handles:

Request validation: Checking file types, sizes, and security
Multipart form parsing: Processing multipart/form-data requests
File processing: Validating and preparing files for storage
Storage upload: Saving files to Edge Storage
Response generation: Returning upload status and file information

Security considerations

File type validation: Only allow specific file types
Size limits: Enforce maximum file size restrictions
Virus scanning: Implement malware detection when possible
Access control: Validate user permissions before uploads
Input sanitization: Clean file names and metadata

Key benefits

Performance: Upload processing at the edge reduces latency
Scalability: Automatically scales with demand
Global reach: Edge locations provide worldwide coverage
Cost efficiency: Optimized data transfer and storage costs

Testing your file upload application

Step 1: Test file upload functionality

Navigate to your deployed application
Use the upload form to test various file types
Verify files are successfully stored in your Edge Storage bucket
Test file size limits and type restrictions

Step 2: Test security features

File type validation: Try uploading restricted file types
Size limits: Test with files exceeding your size limit
Malicious files: Test with files containing suspicious content
Path traversal: Verify file name sanitization

Step 3: Performance testing

Upload speed: Test with various file sizes
Concurrent uploads: Test multiple simultaneous uploads
Error handling: Test network interruptions and failures

Common use cases

Document management: Upload and store business documents
Image galleries: Handle photo and image uploads
Media content: Process video and audio file uploads
Form attachments: Handle file attachments in web forms
Data import: Process CSV and data file uploads

Troubleshooting

Common issues and solutions

Upload failures: Check file size limits and allowed types
Storage errors: Verify bucket permissions and configuration
Performance issues: Optimize file processing and storage operations
Security concerns: Review file validation and sanitization logic

Error handling best practices

Clear error messages: Provide specific feedback to users
Logging: Implement comprehensive error logging
Retry mechanisms: Handle temporary failures gracefully
Progress indicators: Show upload progress for large files

Advanced features

Implementing file processing

You can extend the basic upload functionality with:

Image resizing: Automatically resize uploaded images
Format conversion: Convert files to different formats
Metadata extraction: Extract and store file metadata
Thumbnail generation: Create preview images

Adding authentication

Implement user authentication to secure file uploads:

// Example authentication check
function authenticateUser(request) {
    const authHeader = request.headers.get('Authorization');
    // Implement your authentication logic
    return validateToken(authHeader);
}

Next steps

Explore advanced file processing techniques
Implement file deletion and management features
Add user authentication and authorization
Integrate with other Azion products like Edge Cache
Monitor upload performance and optimize accordingly