What is a data source in Terraform?

A data source in Terraform serves as a read-only reference that enables users to fetch and utilize information from existing resources that are managed outside of Terraform or by separate configurations. This feature is essential for integrating with existing infrastructure, allowing you to reference attributes of resources that have already been created. By using data sources, you can gather information such as instance IDs, security group attributes, or any other relevant data that you need to incorporate into your configuration without having to create those resources again.

This capability promotes a modular and efficient approach to building infrastructure, as it allows for the reuse of existing elements rather than duplicating efforts. It enhances collaboration within teams and ensures that your configurations are aware of the up-to-date state of existing resources.

In contrast, the other choices do not accurately describe what a data source is. Creating new resources refers to resource blocks, while temporary storage for sensitive information pertains to the use of variables or Terraform's sensitive attributes. Managing Terraform modules involves structuring and organizing configuration files, which is different from the function of a data source.