»Initializing Working Directories

Terraform expects to be invoked from a working directory that contains configuration files written in the Terraform language. Terraform uses configuration content from this directory, and also uses the directory to store settings, cached plugins and modules, and sometimes state data.

A working directory must be initialized before Terraform can perform any operations in it (like provisioning infrastructure or modifying state).

»Working Directory Contents

A Terraform working directory typically contains:

• A Terraform configuration describing resources Terraform should manage. This configuration is expected to change over time.
• A hidden .terraform directory, which Terraform uses to manage cached provider plugins and modules, record which workspace is currently active, and record the last known backend configuration in case it needs to migrate state on the next run. This directory is automatically managed by Terraform, and is created during initialization.
• State data, if the configuration uses the default local backend. This is managed by Terraform in a terraform.tfstate file (if the directory only uses the default workspace) or a terraform.tfstate.d directory (if the directory uses multiple workspaces).

»Initialization

Run the terraform init command to initialize a working directory that contains a Terraform configuration. After initialization, you will be able to perform other commands, like terraform plan and terraform apply.

If you try to run a command that relies on initialization without first initializing, the command will fail with an error and explain that you need to run init.

Initialization performs several tasks to prepare a directory, including accessing state in the configured backend, downloading and installing provider plugins, and downloading modules. Under some conditions (usually when changing from one backend to another), it might ask the user for guidance or confirmation.

For details, see the terraform init command.

»Reinitialization

Certain types of changes to a Terraform configuration can require reinitialization before normal operations can continue. This includes changes to provider requirements, module sources or version constraints, and backend configurations.

You can reinitialize a directory by running terraform init again. In fact, you can reinitialize at any time; the init command is idempotent, and will have no effect if no changes are required.

If reinitialization is required, any commands that rely on initialization will fail with an error and tell you so.

»Reinitializing Only Modules

The terraform get command will download modules referenced in the configuration, but will not perform the other required initialization tasks. This command is only useful for niche workflows, and most Terraform users can ignore it in favor of terraform init.