Using presigend urls for large downloads in NestJS on Lambda

Introduce

In Lambda, the payload for request, response is limited to 6mb.
So when someone download a file larger than 6mb. it gives and error.

Response payload size exceeded maximum allowed payload size

Working with presigned URLs

Normally, access a link to a file in S3, it will download.
So I’m going to use the presigend url.

Working with presigned URLs

Code

This is an example of using the AWS-SDK to get a get sigend url.
I wanted to change the file name on download and use a ResponseContentDisposition.
One thing to check here is that you need to encode file name.

const S3 = new AWS.S3({
      region: this.configService.get('AWS_DEFAULT_REGION'),
      credentials: {
        accessKeyId: this.configService.get('AWS_ACCESS_KEY_ID'),
        secretAccessKey: this.configService.get('AWS_SECRET_ACCESS_KEY'),
      },
    });

const encodedFilename = encodeURIComponent(file.title);

const url = await S3.getSignedUrl('getObject', {
 Bucket: this.configService.get('AWS_PRIVATE_BUCKET'),
 Key: file.path,
 Expires: 60,
 ResponseContentDisposition: 'attachment; filename="' + encodedFilename + '"',
});

The example above uses the AWS-SDK and was prompted to switch to the v3 version.

So I rewrote the code to use the v3 version.

const s3 = new S3Client({
 region: this.configService.get('AWS_REGION'),
 credentials: {
  accessKeyId: this.configService.get('AWS_KEY'),
  secretAccessKey: this.configService.get('AWS_SECRET'),
 },
});

const encodedFilename = encodeURIComponent(file.title);

const command = new GetObjectCommand({
 Bucket: this.configService.get('AWS_BUCKET'),
 Key: file.path,
 ResponseContentDisposition:
'attachment; filename="' + encodedFilename + '"',
});

const url = await getSignedUrl(s3, command, { expiresIn: 60 });