Where is Terraform unable to load a provider from?

Terraform is unable to load a provider from source code because providers need to be built and compiled into binary executables that Terraform can interact with. While Terraform does allow for the use of custom providers, these must be available as executables accessible to Terraform, typically downloaded from a provider registry or included as an external library.

For example, the provider registry hosts pre-built binaries that Terraform can easily download and use, thereby simplifying the provider management process. Similarly, external libraries can be included if they follow the required structure and are appropriately packaged.

Terraform modules, which are collections of resources, can include references to these providers, facilitating modular and reusable infrastructure codes. However, the underlying mechanisms of provider loading necessitate that they are in the appropriate format, which is not the case with raw source code. Thus, while source code can be used to create providers, it cannot be directly loaded by Terraform for operations.