CloudTrail Log Analytics using AWS Lambda and Amazon ElasticSearch Service

This AWS Serverless Application will help you analyze AWS CloudTrail Logs using Amazon Elasticsearch Service. The application creates CloudTrail trail, sets the log delivery to an s3 bucket that it creates and configures SNS delivery whenever the CloudTrail log file has been written to s3. The app also creates an Amazon Elasticsearch Domain and creates an Amazon Lambda Function which gets triggered by the SNS message, get the s3 file location, read the contents from the s3 file and write the data to Elasticsearch for analytics.

This is the architecture of the CloudTrail Log Analytics Serverless Application

The remainder of document explains how to prepare the Serverless Application and deploy it via AWS CloudFormation.

Prerequisites

• python 2.7
• pip

Install the required python packages for the AWS Lambda function

$ python -m pip install -r requirements.txt -t ./

Packing Artifacts

Before you can deploy a SAM template, you should first upload your Lambda function code zip. Set the CodeUri properties to the S3 URI of uploaded files. You can choose to do this manually or use aws cloudformation package CLI command to automate the task of uploading local artifacts to S3 bucket. The command returns a copy of your template, replacing references to local artifacts with S3 location where the command uploaded your artifacts.

To use this command, set CodeUri property to be the path to your source code folder/zip/jar as shown in the example below.

This is already taken care for you, the below documentation is for reference

Function:
    Type: AWS::Serverless::Function
    Properties:
        CodeUri: ./
        ...

Run the following command to upload your artifacts to S3 and output a packaged template that can be readily deployed to CloudFormation.

$ aws cloudformation package \
    --template-file template.yaml \
    --s3-bucket bucket-name \
    --output-template-file serverless-output.yaml

The packaged template will look something like this:

Function:
    Type: AWS::Serverless::Function
    Properties:
        CodeUri: s3://<mybucket>/<my-zipfile-path>
        ...

Deploying to AWS CloudFormation

SAM template is deployed to AWS CloudFormation by creating a changeset using the SAM template followed by executing the changeset. Think of a ChangeSet as a diff between your current stack template and the new template that you are deploying. After you create a ChangeSet, you have the opportunity to examine the diff before executing it. Both the AWS Console and AWS CLI provide commands to create and execute a changeset.

Alternatively, you can use aws cloudformation deploy CLI command to deploy the SAM template. Under-the-hood it creates and executes a changeset and waits until the deployment completes. It also prints debugging hints when the deployment fails. Run the following command to deploy the packaged template to a stack called cloudtrail-log-analytics:

$ aws cloudformation deploy \
    --template-file serverless-output.yaml \
    --stack-name cloudtrail-log-analytics \
    --capabilities CAPABILITY_IAM

Refer to the documentation for more details.

Caveats

Please read this part

The Amazon Elasticsearch Domain that the Serverless Application creates has the following access polices:

• es:ESHttp* access to everyone to the domain

I strongly recommend reading about Elasticsearch Service Access Policies using the below documentation and modify the Access policy of the Elasticsearch domain to give full access to the Lambda's IAM role or give full es:ESHttp* access to your public IPs to the Elasticsearch Domain