terraform/website/source/docs/configuration/providers.html.md

layout	page_title	sidebar_current	description
docs	Configuring Providers	docs-config-providers	Providers are responsible in Terraform for managing the lifecycle of a resource: create, read, update, delete.

Provider Configuration

Providers are responsible in Terraform for managing the lifecycle of a resource: create, read, update, delete.

Every resource in Terraform is mapped to a provider based on longest-prefix matching. For example the aws_instance resource type would map to the aws provider (if that exists).

Most providers require some sort of configuration to provide authentication information, endpoint URLs, etc. Provider configuration blocks are a way to set this information globally for all matching resources.

This page assumes you're familiar with the configuration syntax already.

Example

A provider configuration looks like the following:

provider "aws" {
  access_key = "foo"
  secret_key = "bar"
  region     = "us-east-1"
}

Description

The provider block configures the provider of the given NAME. Multiple provider blocks can be used to configure multiple providers.

Terraform matches providers to resources by matching two criteria. Both criteria must be matched for a provider to manage a resource:

• They must share a common prefix. Longest matching prefixes are tried first. For example, aws_instance would choose the aws provider.

• The provider must report that it supports the given resource type. Providers internally tell Terraform the list of resources they support.

Within the block (the { }) is configuration for the resource. The configuration is dependent on the type, and is documented for each provider.

Initialization

Each time a new provider is added to configuration -- either explicitly via a provider block or by adding a resource from that provider -- it's necessary to initialize that provider before use. Initialization downloads and installs the provider's plugin and prepares it to be used.

Provider initialization is one of the actions of terraform init. Running this command will download and initialize any providers that are not already initialized.

For more information, see the terraform init command.

Provider Versions

Providers are released on a separate rhythm from Terraform itself, and thus have their own version numbers. For production use, it is recommended to constrain the acceptable provider versions via configuration, to ensure that new versions with breaking changes will not be automatically installed by terraform init in future.

When terraform init is run without provider version constraints, it prints a suggested version constraint string for each provider:

The following providers do not have any version constraints in configuration,
so the latest version was installed.

To prevent automatic upgrades to new major versions that may contain breaking
changes, it is recommended to add version = "..." constraints to the
corresponding provider blocks in configuration, with the constraint strings
suggested below.

* provider.aws: version = "~> 1.0"

To constrain the provider version as suggested, add a version argument to the provider configuration block:

provider "aws" {
  version = "~> 1.0"

  access_key = "foo"
  secret_key = "bar"
  region     = "us-east-1"
}

This special argument applies to all providers. terraform providers can be used to view the specified version constraints for all providers used in the current configuration.

Multiple Provider Instances

You can define multiple instances of the same provider in order to support multiple regions, multiple hosts, etc. The primary use case for this is utilizing multiple cloud regions. Other use cases include targeting multiple Docker hosts, multiple Consul hosts, etc.

To define multiple provider instances, repeat the provider configuration multiple times, but set the alias field and name the provider. For example:

# The default provider
provider "aws" {
  # ...
}

# West coast region
provider "aws" {
  alias  = "west"
  region = "us-west-2"
}

After naming a provider, you reference it in resources with the provider field:

resource "aws_instance" "foo" {
  provider = "aws.west"

  # ...
}

If a provider isn't specified, then the default provider configuration is used (the provider configuration with no alias set). The value of the provider field is TYPE.ALIAS, such as "aws.west" above.

Syntax

The full syntax is:

provider NAME {
  CONFIG ...
  [alias = ALIAS]
}

where CONFIG is:

KEY = VALUE

KEY {
  CONFIG
}

Interpolation

Providers support interpolation syntax allowing dynamic configuration at run time.

provider "aws" {
  region = "${var.aws_region}"
}

-> 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 and data sources, including remote state may be used in an interpolation inside a provider stanza.