index.js

// dependencies
const AWS = require('aws-sdk');
const util = require('util');

const moment = require('moment')
const parser = require('xml2json');


// get reference to S3 client
const s3 = new AWS.S3();

exports.handler = async (event, context, callback) => {

    // Read options from the event parameter.
    console.log("Reading options from event:\n", util.inspect(event, {depth: 5}));
    const srcBucket = event.Records[0].s3.bucket.name;
    
    // Object key may have spaces or unicode non-ASCII characters.
    const srcKey    = decodeURIComponent(event.Records[0].s3.object.key.replace(/\+/g, " "));
    const dstBucket = srcBucket + "-target";

    console.log("source bucket - " + srcBucket)

    console.log("destination bucket - " + dstBucket)
    // Download the xml from the S3 source bucket. 

    try {
        const params = {
            Bucket: srcBucket,
            Key: srcKey
        };
        var metadata_xml = await s3.getObject(params).promise();

    } catch (error) {
        console.log(error);
        return;
    }  


    // create outfile_name with date string
    
    let dt_str = moment().format('YYYYDDMM');
    // const basename = 'Metadata'
    const output_ext = '.json'

    const output_file_name = "".concat(srcKey.slice(0, -4), "_" , dt_str, output_ext)

   
    // Use the xml2json module to convert the file.
    try { 

        var buffer = parser.toJson(metadata_xml.Body);
            
    } catch (error) {
        console.log(error);
        return;
    } 

    // Upload the json to the destination bucket
    try {
        const destparams = {
            Bucket: dstBucket,
            Key: output_file_name,
            Body: buffer,
            ContentType: "json"
        };

        const putResult = await s3.putObject(destparams).promise(); 
        
    } catch (error) {
        console.log(error);
        return;
    } 
        
    console.log('Successfully converted to json ' + srcBucket + '/' + srcKey +
        ' and uploaded to ' + dstBucket + '/' + output_file_name); 
}