terraform/website/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.

When terraform init is re-run with providers already installed, it will use an already-installed provider that meets the constraints in preference to downloading a new version. To upgrade to the latest acceptable version of each provider, run terraform init -upgrade. This command also upgrades to the latest versions of all Terraform modules.

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}"
}

An exception to this is the special version attribute that applies to all provider blocks for specifying provider versions; interpolation is not supported for provider versions since provider compatibility is a property of the configuration rather than something dynamic, and provider plugin installation happens too early for variables to be resolvable in this context.

-> 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. Local values can also be used, but currently may fail when running terraform destroy.

Third-party Plugins

At present Terraform can automatically install only the providers distributed by HashiCorp. Third-party providers can be manually installed by placing their plugin executables in one of the following locations depending on the host operating system:

• On Windows, in the sub-path terraform.d/plugins beneath your user's "Application Data" directory.
• On all other systems, in the sub-path .terraform.d/plugins in your user's home directory.

terraform init will search this directory for additional plugins during plugin initialization.

The naming scheme for provider plugins is terraform-provider-NAME-vX.Y.Z, and Terraform uses the name to understand the name and version of a particular provider binary. Third-party plugins will often be distributed with an appropriate filename already set in the distribution archive so that it can be extracted directly into the plugin directory described above.

Provider Plugin Cache

By default, terraform init downloads plugins into a subdirectory of the working directory so that each working directory is self-contained. As a consequence, if you have multiple configurations that use the same provider then a separate copy of its plugin will be downloaded for each configuration.

Given that provider plugins can be quite large (on the order of hundreds of megabytes), this default behavior can be inconvenient for those with slow or metered Internet connections. Therefore Terraform optionally allows the use of a local directory as a shared plugin cache, which then allows each distinct plugin binary to be downloaded only once.

To enable the plugin cache, use the plugin_cache_dir setting in the CLI configuration file. For example:

# (Note that the CLI configuration file is _not_ the same as the .tf files
#  used to configure infrastructure.)

plugin_cache_dir = "$HOME/.terraform.d/plugin-cache"

Please note that on Windows it is necessary to use forward slash separators (/) rather than the conventional backslash (\) since the configuration file parser considers a backslash to begin an escape sequence.

Setting this in the configuration file is the recommended approach for a persistent setting. Alternatively, the TF_PLUGIN_CACHE_DIR environment variable can be used to enable caching or to override an existing cache directory within a particular shell session:

export TF_PLUGIN_CACHE_DIR="$HOME/.terraform.d/plugin-cache"

When a plugin cache directory is enabled, the terraform init command will still access the plugin distribution server to obtain metadata about which plugins are available, but once a suitable version has been selected it will first check to see if the selected plugin is already available in the cache directory. If so, the already-downloaded plugin binary will be used.

If the selected plugin is not already in the cache, it will be downloaded into the cache first and then copied from there into the correct location under your current working directory.

When possible, Terraform will use hardlinks or symlinks to avoid storing a separate copy of a cached plugin in multiple directories. At present, this is not supported on Windows and instead a copy is always created.

The plugin cache directory must not be the third-party plugin directory or any other directory Terraform searches for pre-installed plugins, since the cache management logic conflicts with the normal plugin discovery logic when operating on the same directory.

Please note that Terraform will never itself delete a plugin from the plugin cache once it's been placed there. Over time, as plugins are upgraded, the cache directory may grow to contain several unused versions which must be manually deleted.