initial terraform_data docs

website/data/language-nav-data.json

@@ -94,6 +94,10 @@
             "path": "resources/provisioners/remote-exec"
           }
         ]
+      },
+      {
+        "title": "The <code>terraform_data</code> Resource",
+        "path": "resources/terraform-data"
       }
     ]
   },

website/docs/language/resources/terraform-data.mdx

@@ -0,0 +1,95 @@
+---
+page_title: The terraform_data Managed Resource
+description: >-
+  Retrieves the root module output values from a Terraform state snapshot stored
+  in a remote backend.
+---
+
+# The `terraform_data` Resource
+
+The `terraform_data` implements the standard resource lifecycle, but does not directly take any other actions. 
+You can use the `terraform_data` resource without requiring or configuring a provider. It is always available through a built-in provider with the [source address](/language/providers/requirements#source-addresses) `terraform.io/builtin/terraform`.
+
+The `terraform_data` resource is useful for storing values which need to follow a manage resource lifecycle, and for triggering provisioners when there is no other logical managed resource in which to place them.
+
+
+## Example Usage (data for `replace_triggered_by`)
+
+```hcl
+variable "revision" {
+  default = 1
+}
+
+resource "terraform_data" "replacement" {
+  input = var.revision
+}
+
+# This resource has no convenient attribute which forces replacement,
+# but can now be replaced by any change to the revision variable value.
+resource "example_database" "test" {
+  lifecycle {
+    replace_triggered_by = [terraform_data.replacement]
+  }
+}
+```
+
+## Example Usage (`null_resource` replacement)
+
+```hcl
+resource "aws_instance" "web" {
+  # ...
+}
+
+# A use-case for terraform_data is as a do-nothing container
+# for arbitrary actions taken by a provisioner.
+resource "terraform_data" "bootstrap" {
+  triggers_replace = aws_instance.web.id
+
+  connection {
+    host = aws_instance.web.public_ip
+  }
+
+  provisioner "remote-exec" {
+    inline = [
+      "bootstrap-host.sh,
+    ]
+  }
+}
+```
+
+## Example Usage (force computed value)
+
+```hcl
+resource "example_resource" "test" {
+  name = "foo"
+}
+
+resource "terraform_data" "example" {
+  input = example_resource.test.name
+}
+
+# This resource has a problem where it will fail during plan if the
+# contains list of resources has not yet been created.
+resource "example_broken_collection" "test" {
+  # terraform_data.example.output will stand in as a computed attribute
+  # for example_resource.test, which will be unknown until after apply.
+  contains = [terraform_data.example.output]
+}
+```
+
+
+## Argument Reference
+
+The following arguments are supported:
+
+* `input` - (Optional) A value which will be stored in the instance state, and reflected in the `output` attribute after apply.
+
+* `triggers_replace` - (Optional) A value which is stored in the instance state, and will force replacement when the value changes.
+
+## Attributes Reference
+
+In addition to the above, the following attributes are exported:
+
+* `id` - A string value unique to the resource instance.
+
+* `output` - The computed value derived from the `input` argument. During a plan where `output` is unknown, it will still be of the same type as `input`.

website/layouts/language.erb

@@ -142,6 +142,10 @@
             </ul>
           </li>
 
+          <li>
+            <a href="/docs/language/resources/terraform-data.html">Terraform Data Resource</a>
+          </li>
+
         </ul>
       </li> <!-- resources -->