terraform/website/source/docs/internals/resource-addressing.html.markdown

layout	page_title	sidebar_current	description
docs	Internals: Resource Address	docs-internals-resource-addressing	Resource addressing is used to target specific resources in a larger infrastructure.

Resource Addressing

A Resource Address is a string that references a specific resource in a larger infrastructure. The syntax of a resource address is:

<resource_type>.<resource_name>[optional fields]

Required fields:

• resource_type - Type of the resource being addressed.
• resource_name - User-defined name of the resource.

Optional fields may include:

• [N] - where N is a 0-based index into a resource with multiple instances specified by the count meta-parameter. Omitting an index when addressing a resource where count > 1 means that the address references all instances.

Examples

Given a Terraform config that includes:

resource "aws_instance" "web" {
  # ...
  count = 4
}

An address like this:

aws_instance.web[3]

Refers to only the last instance in the config, and an address like this:

aws_instance.web

Refers to all four "web" instances.