github.com/kanishk98/terraform@v1.3.0-dev.0.20220917174235-661ca8088a6a/website/docs/language/settings/backends/configuration.mdx (about)

     1  ---
     2  page_title: Backend Configuration - Configuration Language
     3  ---
     4  
     5  # Backend Configuration
     6  
     7  A backend defines where Terraform stores its [state](/language/state) data files.
     8  
     9  Terraform uses persisted state data to keep track of the resources it manages. Most non-trivial Terraform configurations either [integrate with Terraform Cloud](/language/settings/terraform-cloud) or use a backend to store state remotely. This lets multiple people access the state data and work together on that collection of infrastructure resources.
    10  
    11  This page describes how to configure a backend by adding the [`backend` block](#using-a-backend-block) to your configuration.
    12  
    13  -> **Note:** In Terraform versions before 1.1.0, we classified backends as standard or enhanced. The enhanced label differentiated the [`remote` backend](/language/settings/backends/remote), which could both store state and perform Terraform operations. This classification has been removed. Refer to [Using Terraform Cloud](/cli/cloud) for details about storing state, executing remote operations, and using Terraform Cloud directly from Terraform.
    14  
    15  ## Available Backends
    16  
    17  By default, Terraform uses a backend called [`local`](/language/settings/backends/local), which stores state as a local file on disk. You can also configure one of the built-in backends included in this documentation.
    18  
    19  Some of these backends act like plain remote disks for state files, while others support locking the state while operations are being performed. This helps prevent conflicts and inconsistencies. The built-in backends listed are the only backends. You cannot load additional backends as plugins.
    20  
    21  -> **Note:** We removed the `artifactory`, `etcd`, `etcdv3`, `manta`, and `swift` backends in Terraform v1.3. Information about their behavior in older versions is still available in the [Terraform v1.2 documentation](/language/v1.2.x/settings/backends/configuration). For migration paths from these removed backends, refer to [Upgrading to Terraform v1.3](/language/v1.3.x/upgrade-guides).
    22  
    23  ## Using a Backend Block
    24  
    25  You do not need to configure a backend when using Terraform Cloud because
    26  Terraform Cloud automatically manages state in the workspaces associated with your configuration. If your configuration includes a [`cloud` block](/language/settings/terraform-cloud), it cannot include a `backend` block.
    27  
    28  To configure a backend, add a nested `backend` block within the top-level
    29  `terraform` block. The following example configures the `remote` backend.
    30  
    31  ```hcl
    32  terraform {
    33    backend "remote" {
    34      organization = "example_corp"
    35  
    36      workspaces {
    37        name = "my-app-prod"
    38      }
    39    }
    40  }
    41  ```
    42  
    43  There are some important limitations on backend configuration:
    44  
    45  - A configuration can only provide one backend block.
    46  - A backend block cannot refer to named values (like input variables, locals, or data source attributes).
    47  
    48  ### Credentials and Sensitive Data
    49  
    50  Backends store state in a remote service, which allows multiple people to access it. Accessing remote state generally requires access credentials, since state data contains extremely sensitive information.
    51  
    52  !> **Warning:**  We recommend using environment variables to supply credentials and other sensitive data. If you use `-backend-config` or hardcode these values directly in your configuration, Terraform will include these values in both the `.terraform` subdirectory and in plan files. This can leak sensitive credentials.
    53  
    54  Terraform writes the backend configuration in plain text in two separate files.
    55  - The `.terraform/terraform.tfstate` file contains the backend configuration for the current working directory.
    56  - All plan files capture the information in `.terraform/terraform.tfstate` at the time the plan was created. This helps ensure Terraform is applying the plan to correct set of infrastructure.
    57  
    58  When applying a plan that you previously saved to a file, Terraform uses the backend configuration stored in that file instead of the current backend settings. If that configuration contains time-limited credentials, they may expire before you finish applying the plan. Use environment variables to pass credentials when you need to use different values between the plan and apply steps.
    59  
    60  ### Backend Types
    61  
    62  The block label of the backend block (`"remote"`, in the example above) indicates which backend type to use. Terraform has a built-in selection of backends, and the configured backend must be available in the version of Terraform you are using.
    63  
    64  The arguments used in the block's body are specific to the chosen backend type; they configure where and how the backend will store the configuration's state, and in some cases configure other behavior.
    65  
    66  Some backends allow providing access credentials directly as part of the configuration for use in unusual situations, for pragmatic reasons. However, in normal use, we _do not_ recommend including access credentials as part of the backend configuration. Instead, leave those arguments completely unset and provide credentials using the credentials files or environment variables that are conventional for the target system, as described in the documentation for each backend.
    67  
    68  Refer to the page for each backend type for full details and that type's configuration arguments.
    69  
    70  ### Default Backend
    71  
    72  If a configuration includes no backend block, Terraform defaults to using the `local` backend, which stores state as a plain file in the current working directory.
    73  
    74  ## Initialization
    75  
    76  When you change a backend's configuration, you must run `terraform init` again
    77  to validate and configure the backend before you can perform any plans, applies,
    78  or state operations.
    79  
    80  After you initialize, Terraform creates a `.terraform/` directory locally. This directory contains the most recent backend configuration, including any authentication parameters you provided to the Terraform CLI. Do not check this directory into Git, as it may contain sensitive credentials for your remote backend.
    81  
    82  The local backend configuration is different and entirely separate from the `terraform.tfstate` file that contains [state data](/language/state) about your real-world infrastruture. Terraform stores the `terraform.tfstate` file in your remote backend.
    83  
    84  When you change backends, Terraform gives you the option to migrate
    85  your state to the new backend. This lets you adopt backends without losing
    86  any existing state.
    87  
    88  ~> **Important:** Before migrating to a new backend, we strongly recommend manually backing up your state by copying your `terraform.tfstate` file
    89  to another location.
    90  
    91  ## Partial Configuration
    92  
    93  You do not need to specify every required argument in the backend configuration.
    94  Omitting certain arguments may be desirable if some arguments are provided
    95  automatically by an automation script running Terraform. When some or all of
    96  the arguments are omitted, we call this a _partial configuration_.
    97  
    98  With a partial configuration, the remaining configuration arguments must be
    99  provided as part of [the initialization process](/cli/init).
   100  
   101  There are several ways to supply the remaining arguments:
   102  
   103  - **File**: A configuration file may be specified via the `init` command line.
   104    To specify a file, use the `-backend-config=PATH` option when running
   105    `terraform init`. If the file contains secrets it may be kept in
   106    a secure data store, such as [Vault](https://www.vaultproject.io/),
   107    in which case it must be downloaded to the local disk before running Terraform.
   108  
   109  - **Command-line key/value pairs**: Key/value pairs can be specified via the
   110    `init` command line. Note that many shells retain command-line flags in a
   111    history file, so this isn't recommended for secrets. To specify a single
   112    key/value pair, use the `-backend-config="KEY=VALUE"` option when running
   113    `terraform init`.
   114  
   115  - **Interactively**: Terraform will interactively ask you for the required
   116    values, unless interactive input is disabled. Terraform will not prompt for
   117    optional values.
   118  
   119  If backend settings are provided in multiple locations, the top-level
   120  settings are merged such that any command-line options override the settings
   121  in the main configuration and then the command-line options are processed
   122  in order, with later options overriding values set by earlier options.
   123  
   124  The final, merged configuration is stored on disk in the `.terraform`
   125  directory, which should be ignored from version control. This means that
   126  sensitive information can be omitted from version control, but it will be
   127  present in plain text on local disk when running Terraform.
   128  
   129  When using partial configuration, Terraform requires at a minimum that
   130  an empty backend configuration is specified in one of the root Terraform
   131  configuration files, to specify the backend type. For example:
   132  
   133  ```hcl
   134  terraform {
   135    backend "consul" {}
   136  }
   137  ```
   138  
   139  ### File
   140  
   141  A backend configuration file has the contents of the `backend` block as
   142  top-level attributes, without the need to wrap it in another `terraform`
   143  or `backend` block:
   144  
   145  ```hcl
   146  address = "demo.consul.io"
   147  path    = "example_app/terraform_state"
   148  scheme  = "https"
   149  ```
   150  
   151  `*.backendname.tfbackend` (e.g. `config.consul.tfbackend`) is the recommended
   152  naming pattern. Terraform will not prevent you from using other names but following
   153  this convention will help your editor understand the content and likely provide
   154  better editing experience as a result.
   155  
   156  ### Command-line key/value pairs
   157  
   158  The same settings can alternatively be specified on the command line as
   159  follows:
   160  
   161  ```
   162  $ terraform init \
   163      -backend-config="address=demo.consul.io" \
   164      -backend-config="path=example_app/terraform_state" \
   165      -backend-config="scheme=https"
   166  ```
   167  
   168  The Consul backend also requires a Consul access token. Per the recommendation
   169  above of omitting credentials from the configuration and using other mechanisms,
   170  the Consul token would be provided by setting either the `CONSUL_HTTP_TOKEN`
   171  or `CONSUL_HTTP_AUTH` environment variables. See the documentation of your
   172  chosen backend to learn how to provide credentials to it outside of its main
   173  configuration.
   174  
   175  ## Changing Configuration
   176  
   177  You can change your backend configuration at any time. You can change
   178  both the configuration itself as well as the type of backend (for example
   179  from "consul" to "s3").
   180  
   181  Terraform will automatically detect any changes in your configuration
   182  and request a [reinitialization](/cli/init). As part of
   183  the reinitialization process, Terraform will ask if you'd like to migrate
   184  your existing state to the new configuration. This allows you to easily
   185  switch from one backend to another.
   186  
   187  If you're using multiple [workspaces](/language/state/workspaces),
   188  Terraform can copy all workspaces to the destination. If Terraform detects
   189  you have multiple workspaces, it will ask if this is what you want to do.
   190  
   191  If you're just reconfiguring the same backend, Terraform will still ask if you
   192  want to migrate your state. You can respond "no" in this scenario.
   193  
   194  ## Unconfiguring a Backend
   195  
   196  If you no longer want to use any backend, you can simply remove the
   197  configuration from the file. Terraform will detect this like any other
   198  change and prompt you to [reinitialize](/cli/init).
   199  
   200  As part of the reinitialization, Terraform will ask if you'd like to migrate
   201  your state back down to normal local state. Once this is complete then
   202  Terraform is back to behaving as it does by default.