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AWS Lambda
Developer Guide

Step 2.1: Create a Deployment Package

The deployment package is a .zip file containing your Lambda function code. For this tutorial, you will need to install the async library. To do this, open a command window and navigate to the directory where you intend to store the code file you will copy and save below. Use npm to install the async library as shown below :

npm install async

Node.js

  1. Open a text editor, and then copy the following code.

    Copy
    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"); }); };

    Note

    The code sample is compliant with the Node.js runtimes v6.10 or v4.3. For more information, see Programming Model (Node.js)

  2. Save the file as CloudTrailEventProcessing.js.

  3. Zip the CloudTrailEventProcessing.js file as CloudTrailEventProcessing.zip.

Note

We're using Node.js in this tutorial example, but you can author your Lambda functions in Java or Python too.

Next Step

Step 2.2: Create the Execution Role (IAM Role)

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