Collect Provider Metadata

This topic describes how to create an inferface in the providers you develop that allows you to collect metadata that is unrelated to the resources in the module, such as usage statistics. This is an advanced topic and is not required to use Terraform.

Introduction

In some situations it is beneficial for a provider to offer an interface through which modules can pass it information unrelated to the resources in the module, but scoped on a per-module basis.

Provider metadata allows a provider to declare metadata fields it expects, which individual modules can then populate independently of any provider configuration. While provider configurations are often shared between modules, provider metadata is always module-specific.

Provider metadata is intended primarily for the situation where an official module is developed by the same vendor that produced the provider it is intended to work with, to allow the vendor to indirectly obtain usage statistics for each module via the provider. For that reason, this documentation is presented from the perspective of the provider developer rather than the module developer.

Defining the Schema

Before a provider can receive information from a module, the provider must strictly define the data it can accept. You can do this by setting the ProviderMeta property on your schema.Provider struct. Its value functions similarly to the provider config: a map of strings to the schema.Schema describing the values those strings accept.

Using the Data

When Terraform calls your provider, you can use the schema.ResourceData that your Create, Read, and Update functions already use to get access to the provider metadata being passed. First define a struct that matches your schema, then call the GetProviderSchema method on your schema.ResourceData, passing a pointer to a variable of that type. The variable will be populated with the provider metadata, and will return an error if there was an issue with parsing the data into the struct.

Specifying Data in Modules

To include data in your modules, create a provider_meta nested block under your module's terraform block, with the name of the provider it's trying to pass information to:

terraform {
  provider_meta "my-provider" {
    hello = "world"
  }
}

The provider_meta block must match the schema the provider has defined.

Versioning Your Modules

Any module taking advantage of this functionality must make sure that the provider metadata supplied matches the schema defined in the provider, and that the version of Terraform that is being run has support for the provider metadata functionality. It's therefore recommended that any module taking advantage of this functionality should specify a minimum Terraform version of 0.13.0 or higher, and a minimum version of each of the providers it specifies metadata as the first version the schema being used was supported by the provider.