HCP Terraform: Defining Provider Paths in Nested Terraform Modules for 3rd Party Providers – HashiCorp Help Center

Introduction:

This article addresses the issue of incorrect provider paths in nested Terraform modules when using third-party providers. It provides a solution to prevent `terraform init` failures due to missing `required_providers` blocks.

Expected Outcome

Users should be able to correctly define provider paths in nested Terraform modules, ensuring successful execution of automation tasks.

Prerequisites

Basic understanding of Terraform and its module structure.
Familiarity with third-party providers in Terraform.

Use Case

Consider a scenario with a multi-layer Terraform code with nested modules. The Level 1 module uses a third-party provider to perform a task. The Level 2 module loads the Level 1 module to complete an automation task, and the Level 3 module loads the Level 2 module for comprehensive automation. If the `required_providers` block is not defined in the Level 1 module, Terraform may fail to initialize due to an incorrect provider path.

Solution

To resolve this issue, the `required_providers` block should be defined in the Level 1 module. This block should declare the third-party providers with their sources and versions. By doing this, Terraform will have a central location to reference the third-party providers, ensuring the correct provider paths are used in the lower-level modules. This central location in the top-level module provides the necessary information about all required providers used throughout the nested modules.

Sample Code:

terraform {
   required_providers {
      aws = {
      source = "hashicorp/aws"
      version = "~> 3.0"
      }
      thirdparty-provider = {
      source = "thirdparty-provider/provider"
      version = "~> 1.0"
      }
   }
}

provider "aws" {
    region = "us-east-2"
}

module "level1" {
    source = "./modules/level1"
    // pass any required variables
}

module "level2" {
    source = "./modules/level2"
    // pass any required variables
}

module "level3" {
    source = "./modules/level3"
    // pass any required variables
}

In this example, the `required_providers` block is defined in the top-level module. It declares the AWS provider and a third-party provider with their sources and versions. The module blocks load the Level 1, Level 2, and Level 3 modules.

Additional Information

Provider Requirements documentation:
https://developer.hashicorp.com/terraform/language/providers/requirements

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