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

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---
layout: "docs"
page_title: "Internals: Resource Address"
sidebar_current: "docs-internals-resource-addressing"
description: |-
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.