» Module Sources

As documented in the Usage section, the only required parameter when using a module is source.

The source parameter tells Terraform where the module can be found. Terraform manages modules for you: it downloads them, organizes them on disk, checks for updates, etc. Terraform uses this source parameter to determine where it should retrieve and update modules from.

Terraform supports the following sources:

Each is documented further below.

» Local File Paths

The easiest source is the local file path. For maximum portability, this should be a relative file path into a subdirectory. This allows you to organize your Terraform configuration into modules within one repository, for example:

module "consul" {
  source = "./consul"
}

Updates for file paths are automatic: when "downloading" the module using the get command, Terraform will create a symbolic link to the original directory. Therefore, any changes are automatically available.

» Terraform Registry

The Terraform Registry is an index of modules written by the Terraform community. The Terraform Registry is the easiest way to get started with Terraform and to find modules.

The registry is integrated directly into Terraform. You can reference any registry module with a source string of <NAMESPACE>/<NAME>/<PROVIDER>. Each module's information page on the registry includes its source string.

module "consul" {
  source = "hashicorp/consul/aws"
  version = "0.1.0"
}

The above example would use the Consul module for AWS from the public registry.

Registry modules support versioning. You can provide a specific version, or use flexible version constraints.

You can learn more about the registry at the Terraform Registry documentation.

» Private Registries

Terraform Enterprise provides a private module registry, to help you share code within your organization. Other services can also provide private registries by implementing Terraform's registry API.

Source strings for private registry modules are similar to public modules, but also include a hostname. They should follow the format <HOSTNAME>/<NAMESPACE>/<NAME>/<PROVIDER>.

module "vpc" {
  source = "app.terraform.io/example_corp/vpc/aws"
  version = "0.9.3"
}

Modules from private registries support versioning, just like modules from the public Terraform Registry.

» GitHub

Terraform will automatically recognize GitHub URLs and turn them into a link to the specific Git repository. The syntax is simple:

module "consul" {
  source = "github.com/hashicorp/example"
}

Subdirectories within the repository can also be referenced:

module "consul" {
  source = "github.com/hashicorp/example//subdir"
}

These will fetch the modules using HTTPS. If you want to use SSH instead:

module "consul" {
  source = "git@github.com:hashicorp/example.git//subdir"
}

Note: The double-slash, //, is important. It is what tells Terraform that that is the separator for a subdirectory, and not part of the repository itself.

GitHub source URLs require that Git is installed on your system and that you have access to the repository.

You can use the same parameters to GitHub repositories as you can generic Git repositories (such as tags or branches). See the documentation for generic Git repositories for more information.

» Private GitHub Repos

If you need Terraform to fetch modules from private GitHub repos, you must provide Terraform with credentials to authenticate as a user with read access to those repos.

  • If you run Terraform only on your local machine, you can specify the module source as an SSH URI (like git@github.com:hashicorp/example.git) and Terraform will use your default SSH key to authenticate.
  • If you use Terraform Enterprise, consider using the private module registry. It makes handling credentials easier, and provides full versioning support. (See Private Registries above for more info.)

    If you need to use modules directly from Git, you can use SSH URIs with Terraform Enterprise. You'll need to add an SSH private key to your organization and assign it to any workspace that fetches modules from private repos. See the Terraform Enterprise docs about SSH keys for cloning modules.

  • If you need to run Terraform on a remote machine like a CI worker, you either need to write an SSH key to disk and set the GIT_SSH_COMMAND environment variable appropriately during the worker's provisioning process, or create a GitHub machine user with read access to the repos in question and embed its credentials into the modules' source parameters:

    module "private-infra" {
      source = "git::https://MACHINE-USER:MACHINE-PASS@github.com/org/privatemodules//modules/foo"
    }
    

    Note that Terraform does not support interpolations in the source parameter of a module, so you must hardcode the machine username and password if using this method.

» Bitbucket

Terraform will automatically recognize public Bitbucket URLs and turn them into a link to the specific Git or Mercurial repository, for example:

module "consul" {
  source = "bitbucket.org/hashicorp/consul"
}

Subdirectories within the repository can also be referenced:

module "consul" {
  source = "bitbucket.org/hashicorp/consul//subdir"
}

Note: The double-slash, //, is important. It is what tells Terraform that this is the separator for a subdirectory, and not part of the repository itself.

Bitbucket URLs will require that Git or Mercurial is installed on your system, depending on the type of repository.

» Private Bitbucket Repos

Private bitbucket repositories must be specified similar to the Generic Git Repository section below.

module "consul" {
  source = "git::https://bitbucket.org/foocompany/module_name.git"
}

You can also specify branches and version withs the ?ref query

module "consul" {
  source = "git::https://bitbucket.org/foocompany/module_name.git?ref=hotfix"
}

You will need to run a terraform get -update=true if you want to pull the latest versions. This can be handy when you are rapidly iterating on a module in development.

» Generic Git Repository

Generic Git repositories are also supported. The value of source in this case should be a complete Git-compatible URL. Using generic Git repositories requires that Git is installed on your system.

module "consul" {
  source = "git://hashicorp.com/consul.git"
}

You can also use protocols such as HTTP or SSH to reference a module, but you'll have specify to Terraform that it is a Git module, by prefixing the URL with git:: like so:

module "consul" {
  source = "git::https://hashicorp.com/consul.git"
}

module "ami" {
  source = "git::ssh://git@github.com/owner/repo.git"
}

If you do not specify the type of source then Terraform will attempt to use the closest match, for example assuming https://hashicorp.com/consul.git is a HTTP URL.

Terraform will cache the module locally by default terraform get is run, so successive updates to master or a specified branch will not be factored into future plans. Run terraform get -update=true to get the latest version of the branch. This is handy in development, but potentially bothersome in production if you don't have control of the repository.

» Parameters

The URLs for Git repositories support the following query parameters:

  • ref - The ref to checkout. This can be a branch, tag, commit, etc.
module "consul" {
  source = "git::https://hashicorp.com/consul.git?ref=master"
}

» Generic Mercurial Repository

Generic Mercurial repositories are supported. The value of source in this case should be a complete Mercurial-compatible URL. Using generic Mercurial repositories requires that Mercurial is installed on your system. You must tell Terraform that your source is a Mercurial repository by prefixing it with hg::.

module "consul" {
  source = "hg::http://hashicorp.com/consul.hg"
}

URLs for Mercurial repositories support the following query parameters:

  • rev - The rev to checkout. This can be a branch, tag, commit, etc.
module "consul" {
  source = "hg::http://hashicorp.com/consul.hg?rev=default"
}

» HTTP URLs

An HTTP or HTTPS URL can be used to redirect Terraform to get the module source from one of the other sources. For HTTP URLs, Terraform will make a GET request to the given URL. An additional GET parameter, terraform-get=1, will be appended, allowing you to optionally render the page differently when Terraform is requesting it.

Terraform then looks for the resulting module URL in the following order:

  1. Terraform will look to see if the header X-Terraform-Get is present. The header should contain the source URL of the actual module.

  2. Terraform will look for a <meta> tag with the name of terraform-get, for example:

<meta name="terraform-get" content="github.com/hashicorp/example" />

» S3 Bucket

Terraform can also store modules in an S3 bucket. To access the bucket you must have appropriate AWS credentials in your configuration or available via shared credentials or environment variables.

There are a variety of S3 bucket addressing schemes, most are documented in the S3 configuration. Here are a couple of examples.

Using the s3 protocol.

module "consul" {
  source = "s3::https://s3-eu-west-1.amazonaws.com/consulbucket/consul.zip"
}

Or directly using the bucket's URL.

module "consul" {
  source = "consulbucket.s3-eu-west-1.amazonaws.com/consul.zip"
}

» Unarchiving

Terraform will automatically unarchive files based on the extension of the file being requested (over any protocol). It supports the following archive formats:

  • tar.gz and tgz
  • tar.bz2 and tbz2
  • zip
  • gz
  • bz2