This is the core element of AWS Config, the Configuration Item (CI) is a JSON file that holds all of the information relating to a resource change. This would include configuration information, relationship data as well as metadata surrounding the resource related to the CI. The information that AWS config records is stored within CIs, and a CI is created every time a change occurs on a supported resource. In addition to this, AWS Config also creates CIs for resources with a direct relationship with the source resource that changed to ensure that the change didn't affect these resources too. For example, if you disconnected an EBS volume from an instance, a CI would be created for the volume as well as a CI for the instance that it was attached to as well.  

Taking a closer look at the CI, it's comprised of the following five elements:  

• Metadata: This gathers metadata relating to the resource itself, such as a time stamp, an MD5Hash used for comparing CIs to prevent duplication of data.
• Attributes: This shows common information across resources, such as ARN information, resource types, and tags.
• Relationships: This defines the directly affected relationships between resources.
• Current configuration: Interestingly, this captures the output that is received by running a describe or list API call, using the AWS command-line interface (CLI).
• Related events: This is where the direct interaction with AWS CloudTrail comes into play. It will show the AWS CloudTrail ID of the API that was used which triggered the change that resulted in AWS Config creating the CI.

As explained earlier, all information used by AWS Config is captured within these CIs, meaning that the data can be used by other components of AWS Config, such as configuration streams, configuration history, and configuration snapshots, so let me explain what function each of these components does.