Initialization: terraform init¶
When you run ‘terraform init’ Terraform will read all of the configuration files in your current directory and download all of the required providers for you. These will be placed in a directory called ‘.terraform/providers/…’. It will also identify every module used in your configuration and write the list to ‘.terraform/modules/modules.json’.
When you run ‘terraform init’ Terraform reads every file that ends with ‘.tf’ in the current directory and looks for a block called ‘terraform’, which contains a sub-block called ‘required_providers’. The ‘required_providers’ block contains a list of every 3rd party “provider” required by your terraform configuration. It does not need to include default terraform providers - only 3rd party providers that provide additional functionality.
Important Take-away The first thing to understand here is that, other than the Terraform package itself, nothing is manually downloaded. Terraform will automatically download the components it requires when it is initialized. (I spent a humiliating amount of time figuring this out.) The second thing to understand is that Terraform initialization is not the first step in creating a new plan/deployment. Counter-intuitively, terraform initialization takes place after you’ve written all of the code and right before you actually try to run the plan to do something.
Note: Running terraform init does not verify that your code is without flaws or actually does anything at all. It does perform a basic syntax check, but that’s it.