Which built-in Terraform function can you use to read the contents of a local file called id_rsa.pub?

The correct built-in Terraform function to read the contents of a local file called id_rsa.pub is file("id_rsa.pub"). This function is specifically designed to take a file path as an argument and return the contents of that file as a string. It is very useful for importing configuration data or static information from files into your Terraform configurations.

For example, if you have public keys, configuration settings, or any static text that resides in a separate file, using the file function allows you to dynamically incorporate that information into your Terraform resources without hardcoding values directly within your scripts. The contents read in this manner can then be utilized in various resources, such as securing SSH access to instances.

The other options don't exist as valid built-in functions in Terraform for reading file contents, which is why they would not work as intended. Understanding the available functions in Terraform is crucial for effectively managing resources and utilizing external data sources in your infrastructure as code practices.