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Martin Atkins 6f35c2847b command: Reorganize docs of the local backend's legacy CLI options

We have these funny extra options that date back to before Terraform even
had remote state, which we've preserved along the way by most recently
incorporating them as special-case overrides for the local backend.

The documentation we had for these has grown less accurate over time as
the details have shifted, and was in many cases missing the requisite
caveats that they are only for the local backend and that backend
configuration is the modern, preferred way to deal with the use-cases they
were intended for.

We always have a bit of a tension with this sort of legacy option because
we want to keep them documented just enough to be useful to someone who
finds an existing script/etc using them and wants to know what they do,
but not to take up so much space that they might distract users from
finding the modern alternative they should consider instead.

As a compromise in that vein here I've created a new section about these
options under the local backend documentation, which then gives us the
space to go into some detail about the various behaviors and interactions
and also to discuss their history and our recommended alternatives. I then
simplified all of the other mentions of these in command documentation
to just link to or refer to the local backend documentation. My hope then
is that folks who need to know what these do can still find the docs, but
that information can be kept out of the direct path of new users so they
can focus on learning about remote backends instead.

This is certainly not the most ideal thing ever, but it seemed like the
best compromise between the competing priorities I described above.

2021-03-25 13:56:48 -07:00

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layout, page_title, sidebar_current, description

layout	page_title	sidebar_current	description
language	Backend Type: local	docs-backends-types-enhanced-local	Terraform can store the state remotely, making it easier to version and work with in a team.

local

Kind: Enhanced

The local backend stores state on the local filesystem, locks that state using system APIs, and performs operations locally.

Example Configuration

terraform {
  backend "local" {
    path = "relative/path/to/terraform.tfstate"
  }
}

Data Source Configuration

data "terraform_remote_state" "foo" {
  backend = "local"

  config = {
    path = "${path.module}/../../terraform.tfstate"
  }
}

Configuration variables

The following configuration options are supported:

path - (Optional) The path to the tfstate file. This defaults to "terraform.tfstate" relative to the root module by default.
workspace_dir - (Optional) The path to non-default workspaces.

Command Line Arguments

~> This section describes legacy features that we've preserved for backward compatibility but that we no longer recommend. See below for more details.

For configurations that include a backend "local" block or that default to the local backend by not specifying a backend at all, most commands that either read or write state snapshots from the backend accept the following additional arguments:

-state=FILENAME - overrides the state filename when reading the prior state snapshot.
-state-out=FILENAME - overrides the state filename when writing new state snapshots.

If you use -state without also using -state-out then Terraform will use the -state filename for both -state and -state-out, which means Terraform will overwrite the input file if it creates a new state snapshot.
-backup=FILENAME - overrides the default filename that the local backend would normally choose dynamically to create backup files when it writes new state.

If you use -state without also using -backup then Terraform will use the -state filename as a filename prefix for generating a backup filename. You can use -backup=- (that is, set the filename to just the ASCII dash character) to disable the creation of backup files altogether.

These three options are preserved for backward-compatibility with earlier workflows that predated the introduction of built-in remote state, where users would write wrapper scripts that fetch prior state before running Terraform and then save the new state after Terraform exits, in which case the three arguments would typically all be paths within a temporary directory used just for one operation.

Because these old workflows predate the introduction of the possibility of multiple workspaces, setting them overrides Terraform's usual behavior of selecting a different state filename based on the selected workspace. If you use all three of these options then the selected workspace has no effect on which filenames Terraform will select for state files, and so you'll need to select different filenames yourself if you wish to keep workspace state files distinct from one another.

These three options have no effect for configurations that have a different backend type selected.

We do not recommend using these options in new systems, even if you are running Terraform in automation. Instead, select a different backend which supports remote state and configure it within your root module, which ensures that everyone working on your configuration will automatically retrieve and store state in the correct shared location without any special command line options.

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