upload_file_s3.js

const AWS = require('aws-sdk');
var s3 = new AWS.S3();

exports.handler = (event, context, callback) => {
  
     var params = {
       "Body": event.base64,
       "Bucket": "my-bucket",
       "Key": 'filename.jpeg',
       "ACL": 'public-read',
       "ContentType": 'image/jpeg'
    };
    s3.upload(params, function(err, data){
       if(err) {
           callback(err, null);
       } else {
         callback(null, data);
    });
    
};