github.com/danp/terraform@v0.9.5-0.20170426144147-39d740081351/website/source/docs/configuration/providers.html.md (about)

     1  ---
     2  layout: "docs"
     3  page_title: "Configuring Providers"
     4  sidebar_current: "docs-config-providers"
     5  description: |-
     6    Providers are responsible in Terraform for managing the lifecycle of a resource: create, read, update, delete.
     7  ---
     8  
     9  # Provider Configuration
    10  
    11  Providers are responsible in Terraform for managing the lifecycle
    12  of a [resource](/docs/configuration/resources.html): create,
    13  read, update, delete.
    14  
    15  Every resource in Terraform is mapped to a provider based
    16  on longest-prefix matching. For example the `aws_instance`
    17  resource type would map to the `aws` provider (if that exists).
    18  
    19  Most providers require some sort of configuration to provide
    20  authentication information, endpoint URLs, etc. Provider configuration
    21  blocks are a way to set this information globally for all
    22  matching resources.
    23  
    24  This page assumes you're familiar with the
    25  [configuration syntax](/docs/configuration/syntax.html)
    26  already.
    27  
    28  ## Example
    29  
    30  A provider configuration looks like the following:
    31  
    32  ```hcl
    33  provider "aws" {
    34    access_key = "foo"
    35    secret_key = "bar"
    36    region = "us-east-1"
    37  }
    38  ```
    39  
    40  ## Description
    41  
    42  The `provider` block configures the provider of the given `NAME`.
    43  Multiple provider blocks can be used to configure multiple providers.
    44  
    45  Terraform matches providers to resources by matching two criteria.
    46  Both criteria must be matched for a provider to manage a resource:
    47  
    48  - They must share a common prefix. Longest matching prefixes are tried first.
    49    For example, `aws_instance` would choose the `aws` provider.
    50  
    51  - The provider must report that it supports the given resource type. Providers
    52    internally tell Terraform the list of resources they support.
    53  
    54  Within the block (the `{ }`) is configuration for the resource.
    55  The configuration is dependent on the type, and is documented
    56  [for each provider](/docs/providers/index.html).
    57  
    58  ## Multiple Provider Instances
    59  
    60  You can define multiple instances of the same provider in order to support
    61  multiple regions, multiple hosts, etc. The primary use case for this is
    62  utilizing multiple cloud regions. Other use cases include targeting multiple
    63  Docker hosts, multiple Consul hosts, etc.
    64  
    65  To define multiple provider instances, repeat the provider configuration
    66  multiple times, but set the `alias` field and name the provider. For
    67  example:
    68  
    69  ```hcl
    70  # The default provider
    71  provider "aws" {
    72    # ...
    73  }
    74  
    75  # West coast region
    76  provider "aws" {
    77    alias  = "west"
    78    region = "us-west-2"
    79  }
    80  ```
    81  
    82  After naming a provider, you reference it in resources with the `provider`
    83  field:
    84  
    85  ```hcl
    86  resource "aws_instance" "foo" {
    87    provider = "aws.west"
    88  
    89    # ...
    90  }
    91  ```
    92  
    93  If a provider isn't specified, then the default provider configuration
    94  is used (the provider configuration with no `alias` set). The value of the
    95  `provider` field is `TYPE.ALIAS`, such as "aws.west" above.
    96  
    97  ## Syntax
    98  
    99  The full syntax is:
   100  
   101  ```text
   102  provider NAME {
   103    CONFIG ...
   104    [alias = ALIAS]
   105  }
   106  ```
   107  
   108  where `CONFIG` is:
   109  
   110  ```text
   111  KEY = VALUE
   112  
   113  KEY {
   114    CONFIG
   115  }
   116  ```
   117  
   118  ## Interpolation
   119  Providers support [interpolation syntax](/docs/configuration/interpolation.html) allowing dynamic configuration at run time.
   120  
   121  ```hcl
   122  provider "aws" {
   123    region = "${var.aws_region}"
   124  }
   125  ```
   126  
   127  -> **NOTE:** Because providers are one of the first things loaded when Terraform parses the graph, it is not possible to use the output from modules or resources as inputs to the provider. At this time, only [variables](/docs/configuration/variables.html) and [data sources](/docs/configuration/data-sources.html), including [remote state](/docs/providers/terraform/d/remote_state.html) may be used in an interpolation inside a provider stanza.