» Command: plan

The terraform plan command is used to create an execution plan. Terraform performs a refresh, unless explicitly disabled, and then determines what actions are necessary to achieve the desired state specified in the configuration files.

This command is a convenient way to check whether the execution plan for a set of changes matches your expectations without making any changes to real resources or to the state. For example, terraform plan might be run before committing a change to version control, to create confidence that it will behave as expected.

The optional -out argument can be used to save the generated plan to a file for later execution with terraform apply, which can be useful when running Terraform in automation.

» Usage

Usage: terraform plan [options] [dir]

By default, plan requires no flags and looks in the current directory for the configuration and state file to refresh.

If the command is given an existing saved plan as an argument, the command will output the contents of the saved plan. In this scenario, the plan command will not modify the given plan. This can be used to inspect a planfile.

The command-line flags are all optional. The list of available flags are:

  • -destroy - If set, generates a plan to destroy all the known resources.

  • -detailed-exitcode - Return a detailed exit code when the command exits. When provided, this argument changes the exit codes and their meanings to provide more granular information about what the resulting plan contains:

    • 0 = Succeeded with empty diff (no changes)
    • 1 = Error
    • 2 = Succeeded with non-empty diff (changes present)

  • -input=true - Ask for input for variables if not directly set.

  • -lock=true - Lock the state file when locking is supported.

  • -lock-timeout=0s - Duration to retry a state lock.

  • -no-color - Disables output with coloring.

  • -out=path - The path to save the generated execution plan. This plan can then be used with terraform apply to be certain that only the changes shown in this plan are applied. Read the warning on saved plans below.

  • -parallelism=n - Limit the number of concurrent operation as Terraform walks the graph. Defaults to 10.

  • -refresh=true - Update the state prior to checking for differences.

  • -state=path - Path to the state file. Defaults to "terraform.tfstate". Ignored when remote state is used.

  • -target=resource - A Resource Address to target. This flag can be used multiple times. See below for more information.

  • -var 'foo=bar' - Set a variable in the Terraform configuration. This flag can be set multiple times. Variable values are interpreted as HCL, so list and map values can be specified via this flag.

  • -var-file=foo - Set variables in the Terraform configuration from a variable file. If a terraform.tfvars or any .auto.tfvars files are present in the current directory, they will be automatically loaded. terraform.tfvars is loaded first and the .auto.tfvars files after in alphabetical order. Any files specified by -var-file override any values set automatically from files in the working directory. This flag can be used multiple times.

» Resource Targeting

The -target option can be used to focus Terraform's attention on only a subset of resources. Resource Address syntax is used to specify the constraint. The resource address is interpreted as follows:

  • If the given address has a resource spec, only the specified resource is targeted. If the named resource uses count and no explicit index is specified in the address (i.e. aws_instance.example[3]), all of the instances sharing the given resource name are targeted.

  • If the given address does not have a resource spec, and instead just specifies a module path, the target applies to all resources in the specified module and all of the descendent modules of the specified module.

This targeting capability is provided for exceptional circumstances, such as recovering from mistakes or working around Terraform limitations. It is not recommended to use -target for routine operations, since this can lead to undetected configuration drift and confusion about how the true state of resources relates to configuration.

Instead of using -target as a means to operate on isolated portions of very large configurations, prefer instead to break large configurations into several smaller configurations that can each be independently applied. Data sources can be used to access information about resources created in other configurations, allowing a complex system architecture to be broken down into more manageable parts that can be updated independently.

» Security Warning

Saved plan files (with the -out flag) encode the configuration, state, diff, and variables. Variables are often used to store secrets. Therefore, the plan file can potentially store secrets.

Terraform itself does not encrypt the plan file. It is highly recommended to encrypt the plan file if you intend to transfer it or keep it at rest for an extended period of time.

Future versions of Terraform will make plan files more secure.