Sample function code

var aws  = require('aws-sdk');
var zlib = require('zlib');
var async = require('async');

var EVENT_SOURCE_TO_TRACK = /sns.amazonaws.com/;  
var EVENT_NAME_TO_TRACK   = /CreateTopic/; 
var DEFAULT_SNS_REGION  = 'us-west-2';
var SNS_TOPIC_ARN       = 'The ARN of your SNS topic';

var s3 = new aws.S3();
var sns = new aws.SNS({
    apiVersion: '2010-03-31',
    region: DEFAULT_SNS_REGION
});

exports.handler = function(event, context, callback) {
    var srcBucket = event.Records[0].s3.bucket.name;
    var srcKey = event.Records[0].s3.object.key;
   
    async.waterfall([
        function fetchLogFromS3(next){
            console.log('Fetching compressed log from S3...');
            s3.getObject({
               Bucket: srcBucket,
               Key: srcKey
            },
            next);
        },
        function uncompressLog(response, next){
            console.log("Uncompressing log...");
            zlib.gunzip(response.Body, next);
        },
        function publishNotifications(jsonBuffer, next) {
            console.log('Filtering log...');
            var json = jsonBuffer.toString();
            console.log('CloudTrail JSON from S3:', json);
            var records;
            try {
                records = JSON.parse(json);
            } catch (err) {
                next('Unable to parse CloudTrail JSON: ' + err);
                return;
            }
            var matchingRecords = records
                .Records
                .filter(function(record) {
                    return record.eventSource.match(EVENT_SOURCE_TO_TRACK)
                        && record.eventName.match(EVENT_NAME_TO_TRACK);
                });
                
            console.log('Publishing ' + matchingRecords.length + ' notification(s) in parallel...');
            async.each(
                matchingRecords,
                function(record, publishComplete) {
                    console.log('Publishing notification: ', record);
                    sns.publish({
                        Message:
                            'Alert... SNS topic created: \n TopicARN=' + record.responseElements.topicArn + '\n\n' + 
                            JSON.stringify(record),
                        TopicArn: SNS_TOPIC_ARN
                    }, publishComplete);
                },
                next
            );
        }
    ], function (err) {
        if (err) {
            console.error('Failed to publish notifications: ', err);
        } else {
            console.log('Successfully published all notifications.');
        }
        callback(null,"message");
    });
};