Azure Image Upload & Compression Function

A serverless Azure Function that provides an HTTP endpoint to upload an image, compress it into WebP format, and store it in Azure Blob Storage.

Overview

This function is designed to be a lightweight, scalable, and cost-effective solution for handling image uploads. It intercepts a multipart/form-data request, extracts the image file, uses the high-performance sharp library to compress it, and uploads the result to a specified Azure Blob Storage container. This is ideal for web or mobile applications that need to process user-uploaded images efficiently.

Features

• HTTP Trigger: Simple and accessible via a standard POST request.
• Multipart Form Parsing: Handles file uploads from web forms or clients.
• Image Compression: Automatically compresses images to the modern, efficient WebP format using sharp.
• Configurable Quality: Image compression quality can be controlled via an environment variable.
• Azure Blob Storage Integration: Securely uploads the processed image to a designated blob container.
• Scalable & Serverless: Built on Azure Functions to handle load automatically.

Prerequisites

Before you begin, ensure you have the following installed:

• Node.js (v18 or later recommended)
• Azure Functions Core Tools
• Azure CLI
• An Azure Subscription and an Azure Storage Account

⚙️ Setup and Configuration

1. Clone the Repository

git clone https://github.com/gsamansharma/image-upload-compress
cd image-upload-compress

2. Install Dependencies

npm install

3. Configure Environment Variables

Create a local.settings.json file in the root of the project. This file is used for local development and should not be committed to source control.

local.settings.json Template:

{
  "IsEncrypted": false,
  "Values": {
    "AzureWebJobsStorage": "",
    "FUNCTIONS_WORKER_RUNTIME": "node",
    "AZURE_STORAGE_CONNECTION_STRING": "DefaultEndpointsProtocol=https...your-connection-string",
    "AZURE_STORAGE_CONTAINER_NAME": "your-container-name",
    "IMAGE_QUALITY": "80"
  }
}

• AZURE_STORAGE_CONNECTION_STRING: Get this from your Azure Storage Account access keys.
• AZURE_STORAGE_CONTAINER_NAME: The name of the blob container where images will be stored (e.g., images).
• IMAGE_QUALITY: (Optional) A number from 1-100. Defaults to 80.

🚀 Running Locally

To start the function on your local machine, run the following command from the project root:

func start

The terminal will display the local URL for your uploadImage function, typically http://localhost:7071/api/uploadImage.

API Endpoint

POST /api/uploadImage

Uploads and processes a single image file.

• Method: POST
• Headers:
  • Content-Type: multipart/form-data
• Body: The request body must be multipart/form-data and contain a file field. The field name can be anything (e.g., image, file, upload).

Example Request using cURL:

curl -X POST \
  http://localhost:7071/api/uploadImage \
  -F "image=@/path/to/your/image.jpg"

✅ Success Response (200 OK)

{
  "message": "Image uploaded & compressed successfully!",
  "blobUrl": "https://yourstorageaccount.blob.core.windows.net/your-container/uuid-goes-here.webp",
  "originalSize": 102400,
  "compressedSize": 25600
}

❌ Error Responses

• 400 Bad Request: Sent if the Content-Type is not multipart/form-data or if no file is found in the request.
• 500 Internal Server Error: Sent if an error occurs during compression or upload. The response body will contain the error message.

🔧 Configuration Options

The function's behavior can be customized using the following environment variables:

Variable	Description	Default
AZURE_STORAGE_CONNECTION_STRING	The connection string for the Azure Storage Account.	null
AZURE_STORAGE_CONTAINER_NAME	The name of the blob container for storing images.	null
IMAGE_QUALITY	The quality setting (1-100) for WebP compression.	80

📝 License

This project is licensed under the MIT License — see the LICENSE file for details.

🤝 Contributing

Contributions, issues, and feature requests are welcome!

📧 Contact

Aman Sharma
📩 contact@amansharma.cv
🌐 amansharma.cv

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