318 lines
16 KiB
Markdown
318 lines
16 KiB
Markdown
---
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layout: "docs"
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page_title: "Command: plan"
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sidebar_current: "docs-commands-plan"
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description: |-
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The terraform plan command creates an execution plan.
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---
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# Command: plan
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> **Hands-on:** Try the [Terraform: Get Started](https://learn.hashicorp.com/collections/terraform/aws-get-started?utm_source=WEBSITE&utm_medium=WEB_IO&utm_offer=ARTICLE_PAGE&utm_content=DOCS) collection on HashiCorp Learn.
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The `terraform plan` command creates an execution plan. By default, creating
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a plan consists of:
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* Reading the current state of any already-existing remote objects to make sure
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that the Terraform state is up-to-date.
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* Comparing the current configuration to the prior state and noting any
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differences.
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* Proposing a set of change actions that should, if applied, make the remote
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objects match the configuration.
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The plan command alone will not actually carry out the proposed changes, and
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so you can use this command to check whether the proposed changes match what
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you expected before you apply the changes or share your changes with your
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team for broader review.
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If Terraform detects that no changes are needed to resource instances or to
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root module output values, `terraform plan` will report that no actions need
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to be taken.
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If you are using Terraform directly in an interactive terminal and you expect
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to apply the changes Terraform proposes, you can alternatively run
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[`terraform apply`](./apply.html) directly. By default, the "apply" command
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automatically generates a new plan and prompts for you to approve it.
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You can use the optional `-out=FILE` option to save the generated plan to a
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file on disk, which you can later execute by passing the file to
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[`terraform apply`](./apply.html) as an extra argument. This two-step workflow
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is primarily intended for when
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[running Terraform in automation](https://learn.hashicorp.com/tutorials/terraform/automate-terraform?in=terraform/automation&utm_source=WEBSITE&utm_medium=WEB_IO&utm_offer=ARTICLE_PAGE&utm_content=DOCS).
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If you run `terraform plan` without the `-out=FILE` option then it will create
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a _speculative plan_, which is a description of a the effect of the plan but
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without any intent to actually apply it.
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In teams that use a version control and code review workflow for making changes
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to real infrastructure, developers can use speculative plans to verify the
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effect of their changes before submitting them for code review. However, it's
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important to consider that other changes made to the target system in the
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meantime might cause the final effect of a configuration change to be different
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than what an earlier speculative plan indicated, so you should always re-check
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the final non-speculative plan before applying to make sure that it still
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matches your intent.
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## Usage
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Usage: `terraform plan [options]`
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The `plan` subcommand looks in the current working directory for the root module
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configuration.
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Because the plan command is one of the main commands of Terraform, it has
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a variety of different options, described in the following sections. However,
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most of the time you should not need to set any of these options, because
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a Terraform configuration should typically be designed to work with no special
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additional options for routine work.
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The remaining sections on this page describe the various options:
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* **[Planning Modes](#planning-modes)**: There are some special alternative
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planning modes that you can use for some special situations where your goal
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is not just to change the remote system to match your configuration.
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* **[Planning Options](#planning-options)**: Alongside the special planning
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modes, there are also some options you can set in order to customize the
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planning process for unusual needs.
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* **[Resource Targeting](#resource-targeting)** is one particular
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special planning option that has some important caveats associated
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with it.
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* **[Other Options](#other-options)**: These change the behavior of the planning
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command itself, rather than customizing the content of the generated plan.
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## Planning Modes
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The section above described Terraform's default planning behavior, which is
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intended for changing the remote system to match with changes you've made to
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your configuration.
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Terraform has two alternative planning modes, each of which creates a plan with
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a different intended outcome:
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* **Destroy mode:** creates a plan whose goal is to destroy all remote objects
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that currently exist, leaving an empty Terraform state. This can be useful
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for situations like transient development environments, where the managed
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objects cease to be useful once the development task is complete.
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Activate destroy mode using the `-destroy` command line option.
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* **Refresh-only mode:** creates a plan whose goal is only to update the
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Terraform state and any root module output values to match changes made to
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remote objects outside of Terraform. This can be useful if you've
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intentionally changed one or more remote objects outside of the usual
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workflow (e.g. while responding to an incident) and you now need to reconcile
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Terraform's records with those changes.
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Activate refresh-only mode using the `-refresh-only` command line option.
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In situations where we need to discuss the default planning mode that Terraform
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uses when none of the alternative modes are selected, we refer to it as
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"Normal mode". Because these alternative modes are for specialized situations
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only, some other Terraform documentation only discusses the normal planning
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mode.
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The planning modes are all mutually-exclusive, so activating any non-default
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planning mode disables the "normal" planning mode, and you can't use more than
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one alternative mode at the same time.
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-> **Note:** In Terraform v0.15 and earlier, the `-destroy` option is
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supported only by the `terraform plan` command, and not by the
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`terraform apply` command. To create and apply a plan in destroy mode in
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earlier versions you must run [`terraform destroy`](./destroy.html).
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## Planning Options
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In addition to the planning _modes_ described above, there are also several
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additional options that can modify details of the behavior of the planning
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step.
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When you use `terraform apply` without passing it a saved plan file, it
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incorporates the `terraform plan` command functionality and so the planning
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options in this section, along with the planning mode selection options in
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the previous section, are also available with the same meanings on
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`terraform apply`.
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* `-refresh=false` - Disables the default behavior of synchronizing the
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Terraform state with remote objects before checking for configuration changes.
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This option can potentially make the planning operation faster by reducing
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the number of remote API requests, but it comes at the expense of having
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Terraform not take into account any changes that might've happened outside
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of Terraform, and thus the resulting plan may not be complete or correct.
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This option is not available in the "refresh only" planning mode, because
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it would effectively disable the entirety of the planning operation in that
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case.
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* `-replace=ADDRESS` - Instructs Terraform to plan to replace the single
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resource instance with the given address. If the given instance would
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normally have caused only an "update" action, or no action at all, then
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Terraform will choose a "replace" action instead.
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You can use this option if you have learned that a particular remote object
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has become degraded in some way. If you are using immutable infrastructure
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patterns then you may wish to respond to that by replacing the
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malfunctioning object with a new object that has the same configuration.
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This option is allowed only in the normal planning mode, so this option
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is incompatible with the `-destroy` option.
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The `-replace=...` option is available only from Terraform v1.0 onwards.
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For earlier versions, you can achieve a similar effect (with some caveats)
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using [`terraform taint`](./taint.html).
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* `-target=ADDRESS` - Instructs Terraform to focus its planning efforts only
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on resource instances which match the given address and on any objects that
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those instances depend on.
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This command is for exceptional use only. See
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[Resource Targeting](#resource-targeting)
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below for more information.
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* `-var 'NAME=VALUE` - Sets a value for a single
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[input variable](/docs/language/values/variables.html) declared in the
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root module of the configuration. Use this option multiple times to set
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more than one variable.
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* `-var-file=FILENAME` - Sets values for potentially many
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[input variables](/docs/language/values/variables.html) declared in the
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root module of the configuration, using definitions from a
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["tfvars" file](/docs/language/values/variables.html#variable-definitions-tfvars-files).
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Use this option multiple times to include values from more than one file.
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There are several other ways to set values for input variables in the root
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module, aside from the `-var` and `-var-file` options. For more information,
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see
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[Assigning Values to Root Module Variables](/docs/language/values/variables.html#assigning-values-to-root-module-variables).
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### Resource Targeting
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> **Hands-on:** Try the [Target resources](https://learn.hashicorp.com/tutorials/terraform/resource-targeting?in=terraform/state&utm_source=WEBSITE&utm_medium=WEB_IO&utm_offer=ARTICLE_PAGE&utm_content=DOCS) tutorial on HashiCorp Learn.
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You can use the `-target` option to focus Terraform's attention on only a
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subset of resources.
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You can use [resource address syntax](/docs/cli/state/resource-addressing.html)
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to specify the constraint. Terraform interprets the resource address as follows:
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* If the given address identifies one specific resource instance, Terraform
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will select that instance alone. For resources with either `count` or
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`for_each` set, a resource instance address must include the instance index
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part, like `aws_instance.example[0]`.
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* If the given address identifies a resource as a whole, Terraform will select
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all of the instances of that resource. For resources with either `count`
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or `for_each` set, this means selecting _all_ instance indexes currently
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associated with that resource. For single-instance resources (without
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either `count` or `for_each`), the resource address and the resource instance
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address are identical, so this possibility does not apply.
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* If the given address identifies an entire module instance, Terraform will
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select all instances of all resources that belong to that module instance
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and all of its child module instances.
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Once Terraform has selected one or more resource instances that you've directly
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targeted, it will also then extend the selection to include all other objects
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that those selections depend on either directly or indirectly.
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This targeting capability is provided for exceptional circumstances, such
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as recovering from mistakes or working around Terraform limitations. It
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is *not recommended* to use `-target` for routine operations, since this can
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lead to undetected configuration drift and confusion about how the true state
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of resources relates to configuration.
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Instead of using `-target` as a means to operate on isolated portions of very
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large configurations, prefer instead to break large configurations into
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several smaller configurations that can each be independently applied.
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[Data sources](/docs/language/data-sources/index.html) can be used to access
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information about resources created in other configurations, allowing
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a complex system architecture to be broken down into more manageable parts
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that can be updated independently.
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## Other Options
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The `terraform plan` command also has some other options that are related to
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the input and output of the planning command, rather than customizing what
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sort of plan Terraform will create. These commands are not necessarily also
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available on `terraform apply`, unless otherwise stated in the documentation
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for that command.
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The available options are:
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* `-compact-warnings` - Shows any warning messages in a compact form which
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includes only the summary messages, unless the warnings are accompanied by
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at least one error and thus the warning text might be useful context for
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the errors.
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* `-detailed-exitcode` - Returns a detailed exit code when the command exits.
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When provided, this argument changes the exit codes and their meanings to
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provide more granular information about what the resulting plan contains:
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* 0 = Succeeded with empty diff (no changes)
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* 1 = Error
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* 2 = Succeeded with non-empty diff (changes present)
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* `-input=false` - Disables Terraform's default behavior of prompting for
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input for root module input variables that have not otherwise been assigned
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a value. This option is particular useful when running Terraform in
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non-interactive automation systems.
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* `-lock=false` - Don't hold a state lock during the operation. This is
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dangerous if others might concurrently run commands against the same
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workspace.
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* `-lock-timeout=DURATION` - Unless locking is disabled with `-lock=false`,
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instructs Terraform to retry acquiring a lock for a period of time before
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returning an error. The duration syntax is a number followed by a time
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unit letter, such as "3s" for three seconds.
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* `-no-color` - Disables terminal formatting sequences in the output. Use this
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if you are running Terraform in a context where its output will be
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rendered by a system that cannot interpret terminal formatting.
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* `-out=FILENAME` - Writes the generated plan to the given filename in an
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opaque file format that you can later pass to `terraform apply` to execute
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the planned changes, and to some other Terraform commands that can work with
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saved plan files.
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Terraform will allow any filename for the plan file, but a typical
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convention is to name it `tfplan`. **Do not** name the file with a suffix
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that Terraform recognizes as another file format; if you use a `.tf` suffix
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then Terraform will try to interpret the file as a configuration source
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file, which will then cause syntax errors for subsequent commands.
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The generated file is not in any standard format intended for consumption
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by other software, but the file _does_ contain your full configuration,
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all of the values associated with planned changes, and all of the plan
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options including the input variables. If your plan includes any sort of
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sensitive data, even if obscured in Terraform's terminal output, it will
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be saved in cleartext in the plan file. You should therefore treat any
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saved plan files as potentially-sensitive artifacts.
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* `-parallelism=n` - Limit the number of concurrent operation as Terraform
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[walks the graph](/docs/internals/graph.html#walking-the-graph). Defaults
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to 10.
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For configurations using
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[the `local` backend](/docs/language/settings/backends/local.html) only,
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`terraform plan` accepts the legacy command line option
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[`-state`](/docs/language/settings/backends/local.html#command-line-arguments).
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### Passing a Different Configuration Directory
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Terraform v0.13 and earlier accepted an additional positional argument giving
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a directory path, in which case Terraform would use that directory as the root
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module instead of the current working directory.
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That usage was deprecated in Terraform v0.14 and removed in Terraform v0.15.
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If your workflow relies on overriding the root module directory, use
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[the `-chdir` global option](./#switching-working-directory-with-chdir)
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instead, which works across all commands and makes Terraform consistently look
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in the given directory for all files it would normally read or write in the
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current working directory.
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If your previous use of this legacy pattern was also relying on Terraform
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writing the `.terraform` subdirectory into the current working directory even
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though the root module directory was overridden, use
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[the `TF_DATA_DIR` environment variable](/docs/cli/config/environment-variables.html#tf_data_dir)
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to direct Terraform to write the `.terraform` directory to a location other
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than the current working directory.
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