---
layout: "language"
page_title: "The lifecycle Meta-Argument - Configuration Language"
---

# The `lifecycle` Meta-Argument

The general lifecycle for resources is described in the
[Resource Behavior](/docs/language/resources/behavior.html) page. Some details of
that behavior can be customized using the special nested `lifecycle` block
within a resource block body:

```hcl
resource "azurerm_resource_group" "example" {
  # ...

  lifecycle {
    create_before_destroy = true
  }
}
```

## Syntax and Arguments

`lifecycle` is a nested block that can appear within a resource block.
The `lifecycle` block and its contents are meta-arguments, available
for all `resource` blocks regardless of type.

The following arguments can be used within a `lifecycle` block:

* `create_before_destroy` (bool) - By default, when Terraform must change
  a resource argument that cannot be updated in-place due to
  remote API limitations, Terraform will instead destroy the existing object
  and then create a new replacement object with the new configured arguments.

    The `create_before_destroy` meta-argument changes this behavior so that
    the new replacement object is created _first,_ and the prior object
    is destroyed after the replacement is created.

    This is an opt-in behavior because many remote object types have unique
    name requirements or other constraints that must be accommodated for
    both a new and an old object to exist concurrently. Some resource types
    offer special options to append a random suffix onto each object name to
    avoid collisions, for example. Terraform CLI cannot automatically activate
    such features, so you must understand the constraints for each resource
    type before using `create_before_destroy` with it.

* `prevent_destroy` (bool) - This meta-argument, when set to `true`, will
  cause Terraform to reject with an error any plan that would destroy the
  infrastructure object associated with the resource, as long as the argument
  remains present in the configuration.

    This can be used as a measure of safety against the accidental replacement
    of objects that may be costly to reproduce, such as database instances.
    However, it will make certain configuration changes impossible to apply,
    and will prevent the use of the `terraform destroy` command once such
    objects are created, and so this option should be used sparingly.

    Since this argument must be present in configuration for the protection to
    apply, note that this setting does not prevent the remote object from
    being destroyed if the `resource` block were removed from configuration
    entirely: in that case, the `prevent_destroy` setting is removed along
    with it, and so Terraform will allow the destroy operation to succeed.

* `ignore_changes` (list of attribute names) - By default, Terraform detects
  any difference in the current settings of a real infrastructure object
  and plans to update the remote object to match configuration.

    The `ignore_changes` feature is intended to be used when a resource is
    created with references to data that may change in the future, but should
    not affect said resource after its creation. In some rare cases, settings
    of a remote object are modified by processes outside of Terraform, which
    Terraform would then attempt to "fix" on the next run. In order to make
    Terraform share management responsibilities of a single object with a
    separate process, the `ignore_changes` meta-argument specifies resource
    attributes that Terraform should ignore when planning updates to the
    associated remote object.

    The arguments corresponding to the given attribute names are considered
    when planning a _create_ operation, but are ignored when planning an
    _update_. The arguments are the relative address of the attributes in the
    resource. Map and list elements can be referenced using index notation,
    like `tags["Name"]` and `list[0]` respectively.

    ```hcl
    resource "aws_instance" "example" {
      # ...

      lifecycle {
        ignore_changes = [
          # Ignore changes to tags, e.g. because a management agent
          # updates these based on some ruleset managed elsewhere.
          tags,
        ]
      }
    }
    ```

    Instead of a list, the special keyword `all` may be used to instruct
    Terraform to ignore _all_ attributes, which means that Terraform can
    create and destroy the remote object but will never propose updates to it.

    Only attributes defined by the resource type can be ignored.
    `ignore_changes` cannot be applied to itself or to any other meta-arguments.

## Literal Values Only

The `lifecycle` settings all affect how Terraform constructs and traverses
the dependency graph. As a result, only literal values can be used because
the processing happens too early for arbitrary expression evaluation.
