Using Presigned URLs for Efficient Image Uploads

When handling file uploads, the traditional approach is to send the file to your server first and then upload it to cloud storage (like S3). This means two uploads—one from the client to your server and another from your server to storage. Not only does this add unnecessary load to your backend, but it also slows down the process.

With presigned URLs, you can skip the middleman. Instead of handling file uploads yourself, you generate a presigned PUT URL on your server and send it to the client. The client then uploads the file directly to storage—eliminating the need for your backend to process large file transfers.

Implementation

async function presignUploadUrl(bucket_name: string, filename: string) {
    // Prepare the command with the S3 SDK
    // Swap this function call depending on the operation you need: GetObject, DeleteObject, etc.
    const command = new PutObjectCommand({
        Bucket: bucket_name,
        Key: filename
    })

    // Send the command to your S3 Bucket
    const signed_url = await getSignedUrl(S3, command);
    return signed_url;
}