Using AWS CloudTrail in PHP – Part 1

AWS CloudTrail is a new service that was announced at AWS re:Invent 2013.

CloudTrail provides a history of AWS API calls for your account, delivered as log files to one of your Amazon S3 buckets. The AWS API call history includes API calls made via the AWS Management Console, AWS SDKs, command line interface, and higher-level AWS services like AWS CloudFormation. Using CloudTrail can help you with security analysis, resource change tracking, and compliance auditing.

Today, I want to show you how to create a trail and start logging API calls using the AWS SDK for PHP. The CloudTrail client is available as of version 2.4.10 of the SDK.

Creating a trail for logging

The easiest way to create a trail is through the AWS Management Console (see Creating and Updating Your Trail), but if you need to create a trail through your PHP code (e.g., automation), you can use the SDK.

Setting up the log file destination

CloudTrail creates JSON-formatted log files containing your AWS API call history and stores them in the Amazon S3 bucket you choose. Before you set up your trail, you must first set up an Amazon S3 bucket with an appropriate bucket policy.

First, create an Amazon S3 client object (e.g., $s3Client).

Creating the Amazon S3 bucket

Use the Amazon S3 client to create a bucket. (Remember, bucket names must be globally unique.)

$bucket = 'YOUR_BUCKET_NAME';

$s3Client->createBucket(array(
    'Bucket' => $bucket
));

$s3Client->waitUntilBucketExists(array(
    'Bucket' => $bucket
));

Creating the bucket policy

Once the bucket is available, you need to create a bucket policy. This policy should grant the the CloudTrail service the access it needs to upload log files into your bucket. The CloudTrail documentation has an example of a bucket policy that we will use in the next code example. You will need to substitute a few of your own values into the example policy including:

Bucket Name: The name of the Amazon S3 bucket where your log files should be delivered.
Account Number: This is your AWS account ID, which is the 12-digit number found on the Account Identifiers section of the AWS Security Credentials page.
Log File Prefix: An optional key prefix you specify when you create a trail that is prepended to the object keys of your log files.

The following code prepares the policy document and applies the policy to the bucket.

$prefix = 'YOUR_LOG_FILE_PREFIX';
$account = 'YOUR_AWS_ACCOUNT_ID';
$policy = <<<POLICY
"Version": "2012-10-17",
"Statement": [
  {
    "Sid": "AWSCloudTrailAclCheck20131101",
    "Effect": "Allow",
    "Principal": {
      "AWS":[
        "arn:aws:iam::086441151436:root",
        "arn:aws:iam::113285607260:root"
      ]
    },
    "Action": "s3:GetBucketAcl",
    "Resource": "arn:aws:s3:::{$bucket}"
  },
  {
    "Sid": "AWSCloudTrailWrite20131101",
    "Effect": "Allow",
    "Principal": {
      "AWS": [
        "arn:aws:iam::086441151436:root",
        "arn:aws:iam::113285607260:root"
      ]
    },
    "Action": "s3:PutObject",
    "Resource": "arn:aws:s3:::{$bucket}/{$prefix}/AWSLogs/{$account}/*",
    "Condition": {
      "StringEquals": {
        "s3:x-amz-acl": "bucket-owner-full-control"
      }
    }
  }
]
POLICY;

$s3Client->putBucketPolicy(array(
    'Bucket' => $bucket,
    'Policy' => $policy,
));

Creating the trail

Now that the bucket has been set up, you can create a trail. Instantiate a CloudTrail client object, then use the createTrail() method of the client to create the trail.

use AwsCloudTrailCloudTrailClient;

$cloudTrailClient = CloudTrailClient::factory(array(
    'key'    => 'YOUR_AWS_ACCESS_KEY_ID',
    'secret' => 'YOUR_AWS_SECRET_KEY',
    'region' => 'us-east-1', // or us-west-2
));

$trailName = 'YOUR_TRAIL_NAME';
$cloudTrailClient->createTrail(array(
    'Name'         => $trailName,
    'S3BucketName' => $bucket,
));

NOTE: Currently, the CloudTrail service only allows for 1 trail at a time.

Start logging

After creating a trail, you can use the SDK to turn on logging via the startLogging() method.

$cloudTrailClient->startLogging(array(
    'Name' => $trailName
));

Your log files are published to your bucket approximately every 5 minutes and contain JSON-formatted data about your AWS API calls. Log files written to your bucket will persist forever by default. However, you can alter your bucket’s lifecycle rules to automatically delete files after a certain retention period or archive them to Amazon Glacier.

Turning it off

If you want to turn off logging, you can use the stopLogging() method.

$cloudTrailClient->stopLogging(array(
    'Name' => $trailName
));

Disabling logging does not delete your trail or log files. You can resume logging by calling the startLogging() method.

In some cases (e.g., during testing) you may want to remove your trail and log files completely. You can delete your trail and bucket using the SDK as well.

Deleting the trail

To delete a trail, use the deleteTrail() method.

$cloudTrailClient->deleteTrail(array(
    'Name' => $trailName
));

Deleting your log files and bucket

To delete the log files and your bucket, you can use the Amazon S3 client.

// Delete all the files in the bucket
$s3Client->clearBucket($bucket);

// Delete the bucket
$s3Client->deleteBucket(array(
    'Bucket' => $bucket
));

Look for Part 2

In the next part of Using AWS CloudTrail in PHP, I’ll show you how you can read your log files and iterate over individual log records using the SDK.

In the meantime, check out the AWS CloudTrail User Guide to learn more about the service.

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