Generate pre-signed URL for S3 upload on AWS Lambda.

index.js

const AWS = require('aws-sdk');
AWS.config.update({
    accessKeyId: 'YOUR_KEY_ID', // Generated on step 1
    secretAccessKey: 'SECRET', // Generated on step 1
    region: 'ap-south-1', // Must be the same as your bucket
    signatureVersion: 'v4',
});
const params = {
    Bucket: 'YOUR_BUCKET_NAME',
    Key: 'FILE_NAME'
};
const options = {
    signatureVersion: 'v4',
    region: 'ap-south-1',
    endpoint: new AWS.Endpoint('https://s3.ap-south-1.amazonaws.com/com.shardul.s3uploadbucket')
 
};
const client = new AWS.S3(options);
exports.handler = async (event) => {
    
    const signedURL = await (new Promise((resolve, reject) => {
        client.getSignedUrl('putObject', params, (err, data) => {
            if (err) {
                reject(err);
            } 
            else {
                resolve(data);
            }
         });
    }));
    return signedURL;
};