---
description: |-
  A resource address is a string that identifies zero or more resource
  instances in your overall configuration.
---

# Resource Addressing

A _resource address_ is a string that identifies zero or more resource
instances in your overall configuration.

An address is made up of two parts:

```
[module path][resource spec]
```

In some contexts OpenTofu might allow for an incomplete resource address that
only refers to a module as a whole, or that omits the index for a
multi-instance resource. In those cases, the meaning depends on the context,
so you'll need to refer to the documentation for the specific feature you
are using which parses resource addresses.

## Module path

A module path addresses a module within the tree of modules. It takes the form:

```
module.module_name[module index]
```

- `module` - Module keyword indicating a child module (non-root). Multiple `module`
  keywords in a path indicate nesting.
- `module_name` - User-defined name of the module.
- `[module index]` - (Optional) [Index](#index-values-for-modules-and-resources)
  to select an instance from a module call that has multiple instances,
  surrounded by square bracket characters (`[` and `]`).

An address without a resource spec, i.e. `module.foo` applies to every resource within
the module if a single module, or all instances of a module if a module has multiple instances.
To address all resources of a particular module instance, include the module index in the address,
such as `module.foo[0]`.

If the module path is omitted, the address applies to the root module.

An example of the `module` keyword delineating between two modules that have multiple instances:

```
module.foo[0].module.bar["a"]
```

## Resource spec

A resource spec addresses a specific resource instance in the selected module.
It has the following syntax:

```
resource_type.resource_name[instance index]
```

- `resource_type` - Type of the resource being addressed.
- `resource_name` - User-defined name of the resource.
- `[instance index]` - (Optional) [Index](#index-values-for-modules-and-resources)
  to select an instance from a resource that has multiple instances,
  surrounded by square bracket characters (`[` and `]`).

A resource spec without a module path prefix matches only resources in the root module.

## Index values for Modules and Resources

The following specifications apply to index values on modules and resources with multiple instances:

- `[N]` where `N` is a `0`-based numerical index into a resource with multiple
  instances specified by the `count` meta-argument. Omitting an index when
  addressing a resource where `count > 1` means that the address references
  all instances.
- `["INDEX"]` where `INDEX` is a alphanumerical key index into a resource with
  multiple instances specified by the `for_each` meta-argument.

## Examples

### count Example

Given a OpenTofu config that includes:

```hcl
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.

### for_each Example

Given a OpenTofu config that includes:

```hcl
resource "aws_instance" "web" {
  # ...
  for_each = {
    "tofu": "value1",
    "resource":  "value2",
    "indexing":  "value3",
    "example":   "value4",
  }
}
```

An address like this:

```
aws_instance.web["example"]
```

Refers to only the "example" instance in the config, and resolves to "value4".
