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Overview

PDF AI uses AWS S3 for reliable and scalable PDF file storage. PDFs are uploaded from the client-side, stored in S3, and later retrieved for processing and viewing.

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Configuration

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Environment Variables

Add your AWS credentials and bucket configuration to .env: 
NEXT_PUBLIC_S3_ACCESS_KEY_ID=your-access-key-id
NEXT_PUBLIC_S3_SECRET_ACCESS_KEY=your-secret-access-key
NEXT_PUBLIC_S3_BUCKET_NAME=your-bucket-name
The NEXT_PUBLIC_ prefix exposes these variables to the client-side. For production, use temporary credentials or a pre-signed URL approach instead.

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S3 Bucket Setup

  1. Create an S3 bucket in the ap-south-1 region (or update the region in code)
  2. Configure CORS to allow uploads from your domain:
[
  {
    "AllowedHeaders": ["*"],
    "AllowedMethods": ["PUT", "POST", "GET"],
    "AllowedOrigins": ["http://localhost:3000", "https://yourdomain.com"],
    "ExposeHeaders": ["ETag"]
  }
]
  1. Set up an IAM user with s3:PutObject, s3:GetObject, and s3:ListBucket permissions

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Client-Side Upload

The uploadToS3() function handles file uploads from the browser (src/lib/s3.ts:4-48): 
import AWS from "aws-sdk";
import toast from "react-hot-toast";

export async function uploadToS3(file: File) {
  try {
    AWS.config.update({
      accessKeyId: process.env.NEXT_PUBLIC_S3_ACCESS_KEY_ID,
      secretAccessKey: process.env.NEXT_PUBLIC_S3_SECRET_ACCESS_KEY,
    });
    
    const s3 = new AWS.S3({
      params: {
        Bucket: process.env.NEXT_PUBLIC_S3_BUCKET_NAME,
      },
      region: "ap-south-1",
    });
    
    const file_key =
      "uploads/" + Date.now().toString() + file.name.replace(" ", "-");

    const params = {
      Bucket: process.env.NEXT_PUBLIC_S3_BUCKET_NAME!,
      Key: file_key,
      Body: file,
    };

    const upload = s3
      .putObject(params)
      .on("httpUploadProgress", (evt) => {
        console.log(
          "upload progress",
          parseInt(((evt.loaded * 100) / evt.total).toString()) + "%"
        );
      })
      .promise();

    await upload.then((data) => {
      toast.success("File uploaded successfully");
    });

    return Promise.resolve({
      file_key,
      file_name: file.name,
    });
  } catch (error) {
    console.log("upload error", error);
  }
}

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Key Features

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Progress Tracking

The upload function provides real-time progress updates: 
.on("httpUploadProgress", (evt) => {
  console.log(
    "upload progress",
    parseInt(((evt.loaded * 100) / evt.total).toString()) + "%"
  );
})

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Unique File Keys

Files are stored with timestamp-based keys to prevent collisions: 
const file_key = "uploads/" + Date.now().toString() + file.name.replace(" ", "-");

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User Feedback

Success notifications are shown using react-hot-toast: 
toast.success("File uploaded successfully");

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Server-Side Download

The server-side function downloads PDFs for processing (src/lib/s3-server.ts:3-28): 
import AWS from "aws-sdk";
import fs from "fs";

export async function downloadFromS3(file_key: string) {
  try {
    AWS.config.update({
      accessKeyId: process.env.NEXT_PUBLIC_S3_ACCESS_KEY_ID,
      secretAccessKey: process.env.NEXT_PUBLIC_S3_SECRET_ACCESS_KEY,
    });
    
    const s3 = new AWS.S3({
      params: {
        Bucket: process.env.NEXT_PUBLIC_S3_BUCKET_NAME,
      },
      region: "ap-south-1",
    });
    
    const params = {
      Bucket: process.env.NEXT_PUBLIC_S3_BUCKET_NAME!,
      Key: file_key,
    };
    
    const obj = await s3.getObject(params).promise();
    const file_name = `D:/pdf-${Date.now()}.pdf`;

    fs.writeFileSync(file_name, obj.Body as Buffer);
    return file_name;
  } catch (error) {
    console.log(error);
    return null;
  }
}
The download function saves files to D:/pdf-{timestamp}.pdf. Update the path for your server environment (e.g., /tmp/ for Linux).

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URL Generation

Generate public URLs for S3 objects (src/lib/s3.ts:50-52): 
export function getS3Url(file_key: string) {
  return `https://${process.env.NEXT_PUBLIC_S3_BUCKET_NAME}.s3.ap-south-1.amazonaws.com/${file_key}`;
}

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API Reference

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uploadToS3

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file
File
required
The File object to upload to S3
Returns: Promise resolving to { file_key: string, file_name: string }

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downloadFromS3

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file_key
string
required
The S3 key of the file to download
Returns: Promise resolving to local file path or null on error

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getS3Url

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file_key
string
required
The S3 key of the file
Returns: Public HTTPS URL to the S3 object

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Dependencies

{
  "aws-sdk": "^2.x.x",
  "react-hot-toast": "^2.x.x"
}

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Best Practices

Never expose AWS credentials in client-side code in production. Use alternatives like:
  • AWS Amplify for managed authentication
  • Pre-signed URLs generated server-side
  • AWS Cognito Identity Pools for temporary credentials

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Security Recommendations

  1. Use Pre-Signed URLs: Generate time-limited upload URLs server-side
  2. Implement Bucket Policies: Restrict access to authorized users only
  3. Enable Encryption: Use S3 server-side encryption (SSE-S3 or SSE-KMS)
  4. Set up Lifecycle Policies: Automatically delete temporary files

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Performance Optimization

  • Multipart Upload: For files larger than 100MB, use multipart uploads
  • CloudFront CDN: Serve PDFs through CloudFront for faster delivery
  • Regional Buckets: Place buckets close to your users

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Troubleshooting

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Upload Failures

  • CORS Errors: Verify CORS configuration in S3 bucket settings
  • 403 Forbidden: Check IAM permissions for s3:PutObject
  • Network Errors: Implement retry logic with exponential backoff

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Download Issues

  • File Not Found: Ensure the file_key exists in the bucket
  • Permission Denied: Verify IAM user has s3:GetObject permission
  • Path Errors: Update the file save path to match your OS (e.g., /tmp/ for Linux)

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