Image Upload Backend

A lightweight, high-performance Go backend server that provides a flexible REST API for temporary image hosting. Upload images via URL, form data, or raw binary—get instant access with automatic cleanup.

Features

• Multiple Upload Methods: JSON URL upload, multipart form upload, and raw binary upload
• Automatic Expiration: Images self-destruct after 2 minutes for enhanced privacy
• Zero Dependencies: Pure Go implementation with standard library only
• RESTful API: Clean, intuitive endpoints for uploads and image access
• Type Preservation: Maintains original file extensions (jpg, png, etc.)
• Thread-Safe: Concurrent upload handling with unique timestamp-based naming
• CORS Enabled: Supports cross-origin requests from web applications

Quick Start

Prerequisites

• Go 1.16 or higher

Installation & Running

# Clone or navigate to the project directory
cd backend

# Run directly
go run main.go

# Or build and run
go build .
./backend

The server starts on http://localhost:8080

API Reference

Upload Image

Endpoint: POST /upload

Upload an image using one of three methods. All methods return the same response format.

Method 1: JSON URL Upload

Perfect for importing images from external sources.

Request:

curl -X POST http://localhost:8080/upload \
  -H "Content-Type: application/json" \
  -d '{"url": "https://example.com/image.jpg"}'

JSON Payload:

{
  "url": "https://example.com/image.jpg"
}

Method 2: Multipart Form Upload

Standard HTML form upload—works with any HTTP client.

Request:

curl -X POST http://localhost:8080/upload \
  -F "image=@/path/to/image.jpg"

Form Field: image (required)

Method 3: Raw Binary Upload

Send image bytes directly with proper content-type header.

Request:

curl -X POST http://localhost:8080/upload \
  -H "Content-Type: image/jpeg" \
  --data-binary @/path/to/image.jpg

Supported Content-Types: image/jpeg, image/png, image/gif, image/webp, etc.

Success Response

Status: 200 OK

{
  "saved_url": "http://localhost:8080/images/1759624622919675760.jpg"
}

Error Responses

Status: 400 Bad Request

Failed to parse multipart form
Invalid JSON
Failed to get uploaded file

Status: 405 Method Not Allowed

Method not allowed

Status: 500 Internal Server Error

Failed to download image
Failed to save image

Access Image

Endpoint: GET /images/{filename}

Retrieve an uploaded image by its filename.

Request:

curl http://localhost:8080/images/1759624622919675760.jpg

Response: Image binary data with appropriate Content-Type header

Status Codes:

• 200 OK - Image found and returned
• 404 Not Found - Image expired or doesn't exist

Image Lifecycle

Upload → Stored (2 minutes) → Automatically Deleted

All uploaded images are automatically deleted 2 minutes after upload. This ensures:

• Privacy protection
• Disk space management
• No manual cleanup required

Note: Accessing an expired image URL will return a 404 Not Found error.

Project Structure

backend/
├── main.go          # Main server implementation
├── go.mod           # Go module definition
├── images/          # Temporary image storage (auto-created)
├── README.md        # This file
└── test_image.jpg   # Test file (optional)

Building for Production

# Build optimized binary
go build -ldflags="-s -w" -o backend .

# Run in background
nohup ./backend > server.log 2>&1 &

# Or use systemd, docker, or your preferred deployment method

Testing

Quick Test Suite

# Test 1: URL Upload
curl -X POST http://localhost:8080/upload \
  -H "Content-Type: application/json" \
  -d '{"url": "https://httpbin.org/image/png"}'

# Test 2: File Upload
echo "test image" > test.jpg
curl -X POST http://localhost:8080/upload \
  -F "[email protected]"

# Test 3: Binary Upload
curl -X POST http://localhost:8080/upload \
  -H "Content-Type: image/jpeg" \
  --data-binary @test.jpg

# Verify image is accessible
curl -I http://localhost:8080/images/{filename_from_response}

# Wait 2+ minutes and verify expiration
sleep 120
curl -I http://localhost:8080/images/{filename_from_response}  # Should return 404

Configuration

Currently hardcoded values you can modify in main.go:

Setting	Value	Location
Port	8080	main() function
Expiration Time	2 minutes	time.AfterFunc(2*time.Minute, ...)
Max Upload Size	32MB	ParseMultipartForm(32 << 20)
Image Directory	images/	os.MkdirAll("images", ...)

Example Use Cases

• Temporary Screenshot Sharing - Share screenshots that auto-delete
• Image Proxy Service - Download and cache external images temporarily
• Development & Testing - Quick image hosting for dev environments
• Mobile App Backend - Temporary image uploads for user avatars/previews
• Bot Integration - Process and host images from chat bots

Integration Examples

JavaScript (Fetch API)

// URL Upload
const uploadFromUrl = async (imageUrl) => {
  const response = await fetch('http://localhost:8080/upload', {
    method: 'POST',
    headers: { 'Content-Type': 'application/json' },
    body: JSON.stringify({ url: imageUrl })
  });
  return await response.json();
};

// File Upload
const uploadFile = async (file) => {
  const formData = new FormData();
  formData.append('image', file);
  const response = await fetch('http://localhost:8080/upload', {
    method: 'POST',
    body: formData
  });
  return await response.json();
};

Python (Requests)

import requests

# URL Upload
def upload_from_url(image_url):
    response = requests.post(
        'http://localhost:8080/upload',
        json={'url': image_url}
    )
    return response.json()

# File Upload
def upload_file(file_path):
    with open(file_path, 'rb') as f:
        response = requests.post(
            'http://localhost:8080/upload',
            files={'image': f}
        )
    return response.json()

HTML Form

<form action="http://localhost:8080/upload" method="POST" enctype="multipart/form-data">
  <input type="file" name="image" accept="image/*" required>
  <button type="submit">Upload Image</button>
</form>

Performance

• Concurrency: Handles multiple simultaneous uploads
• Memory: Efficient streaming for large files
• Startup: < 50ms cold start
• Response Time: < 10ms for local uploads, variable for URL downloads

Security Considerations

This is a basic implementation. For production use, consider:

• Rate limiting to prevent abuse
• Authentication/authorization
• File type validation beyond extension
• Size limits per user/IP
• HTTPS/TLS encryption
• CORS configuration (currently allows all origins for development)
• Input sanitization
• Virus scanning for uploaded files

License

Open source - use freely for any purpose.

Troubleshooting

Port Already in Use

# Find and kill existing process
lsof -i :8080
kill -9 <PID>

Permission Denied (images directory)

mkdir -p images
chmod 755 images

Connection Refused

• Ensure server is running: ps aux | grep backend
• Check server logs: tail -f server.log
• Verify port is listening: netstat -an | grep 8080

Future Enhancements

• Configurable expiration time via environment variables
• Multiple storage backends (S3, local, memory)
• Image transformation (resize, compress, format conversion)
• Upload history and analytics
• Webhook notifications on upload/expiration
• Docker containerization
• Health check endpoint
• Prometheus metrics

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Built with Go | Server ready in < 100 lines of code