terraform/website/docs/internals/provider-meta.html.md

layout	page_title	sidebar_current	description
docs	Provider Metadata	docs-internals-provider-meta	For advanced use cases, modules can provide some pre-defined metadata for providers.

Provider Metadata

In some situations it's 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. The provider metadata functionality allows a provider to do this in a straightforward way.

~> Advanced Topic! This page covers technical details of Terraform. You don't need to understand these details to effectively use Terraform. The details are documented here for module authors and provider developers working on advanced functionality.

~> Experimental Feature! This functionality is still considered experimental, and anyone taking advantage of it should coordinate with the Terraform team to help the team understand how the feature is being used and to make sure their use case is taken into account as the feature develops.

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.