github.com/hugorut/terraform@v1.1.3/website/docs/cli/state/resource-addressing.mdx (about)

     1  ---
     2  page_title: 'Internals: Resource Address'
     3  description: |-
     4    A resource address is a string that identifies zero or more resource
     5    instances in your overall configuration.
     6  ---
     7  
     8  # Resource Addressing
     9  
    10  A _resource address_ is a string that identifies zero or more resource
    11  instances in your overall configuration.
    12  
    13  An address is made up of two parts:
    14  
    15  ```
    16  [module path][resource spec]
    17  ```
    18  
    19  In some contexts Terraform might allow for an incomplete resource address that
    20  only refers to a module as a whole, or that omits the index for a
    21  multi-instance resource. In those cases, the meaning depends on the context,
    22  so you'll need to refer to the documentation for the specific feature you
    23  are using which parses resource addresses.
    24  
    25  ## Module path
    26  
    27  A module path addresses a module within the tree of modules. It takes the form:
    28  
    29  ```
    30  module.module_name[module index]
    31  ```
    32  
    33  - `module` - Module keyword indicating a child module (non-root). Multiple `module`
    34    keywords in a path indicate nesting.
    35  - `module_name` - User-defined name of the module.
    36  - `[module index]` - (Optional) [Index](#index-values-for-modules-and-resources)
    37    to select an instance from a module call that has multiple instances,
    38    surrounded by square bracket characters (`[` and `]`).
    39  
    40  An address without a resource spec, i.e. `module.foo` applies to every resource within
    41  the module if a single module, or all instances of a module if a module has multiple instances.
    42  To address all resources of a particular module instance, include the module index in the address,
    43  such as `module.foo[0]`.
    44  
    45  If the module path is omitted, the address applies to the root module.
    46  
    47  An example of the `module` keyword delineating between two modules that have multiple instances:
    48  
    49  ```
    50  module.foo[0].module.bar["a"]
    51  ```
    52  
    53  -> Module index only applies to modules in Terraform v0.13 or later. In earlier
    54  versions of Terraform, a module could not have multiple instances.
    55  
    56  ## Resource spec
    57  
    58  A resource spec addresses a specific resource instance in the selected module.
    59  It has the following syntax:
    60  
    61  ```
    62  resource_type.resource_name[instance index]
    63  ```
    64  
    65  - `resource_type` - Type of the resource being addressed.
    66  - `resource_name` - User-defined name of the resource.
    67  - `[instance index]` - (Optional) [Index](#index-values-for-modules-and-resources)
    68    to select an instance from a resource that has multiple instances,
    69    surrounded by square bracket characters (`[` and `]`).
    70  
    71  -> In Terraform v0.12 and later, a resource spec without a module path prefix
    72  matches only resources in the root module. In earlier versions, a resource spec
    73  without a module path prefix would match resources with the same type and name
    74  in any descendent module.
    75  
    76  ## Index values for Modules and Resources
    77  
    78  The following specifications apply to index values on modules and resources with multiple instances:
    79  
    80  - `[N]` where `N` is a `0`-based numerical index into a resource with multiple
    81    instances specified by the `count` meta-argument. Omitting an index when
    82    addressing a resource where `count > 1` means that the address references
    83    all instances.
    84  - `["INDEX"]` where `INDEX` is a alphanumerical key index into a resource with
    85    multiple instances specified by the `for_each` meta-argument.
    86  
    87  ## Examples
    88  
    89  ### count Example
    90  
    91  Given a Terraform config that includes:
    92  
    93  ```hcl
    94  resource "aws_instance" "web" {
    95    # ...
    96    count = 4
    97  }
    98  ```
    99  
   100  An address like this:
   101  
   102  ```
   103  aws_instance.web[3]
   104  ```
   105  
   106  Refers to only the last instance in the config, and an address like this:
   107  
   108  ```
   109  aws_instance.web
   110  ```
   111  
   112  Refers to all four "web" instances.
   113  
   114  ### for_each Example
   115  
   116  Given a Terraform config that includes:
   117  
   118  ```hcl
   119  resource "aws_instance" "web" {
   120    # ...
   121    for_each = {
   122      "terraform": "value1",
   123      "resource":  "value2",
   124      "indexing":  "value3",
   125      "example":   "value4",
   126    }
   127  }
   128  ```
   129  
   130  An address like this:
   131  
   132  ```
   133  aws_instance.web["example"]
   134  ```
   135  
   136  Refers to only the "example" instance in the config.