AWS provider version 4.0.0 issues: How do I lock the version in the Reference Architecture (or Terragrunt for that matter)?

[yorinasub17]

When using terragrunt with the Service Catalog, I can't lock the provider version because injecting a terraform block with required_providers (e.g., via generate) results in an error:

╷
│ Error: Duplicate required providers configuration
│
│   on provider_version.tf line 3, in terraform:
│    3:   required_providers {
│
│ A module may have only one required providers configuration. The required
│ providers were previously configured at main.tf:11,3-21.
╵

This is especially problematic now that AWS provider version 4.0 is released and it is breaking all the modules. How do I work around this and lock my provider version to 3.x series?

[yorinasub17]

You can work around this by using an override file in the generate block. The following generate block is confirmed to properly lock the version and work around this error. You can add this to the root terragrunt.hcl file to ensure all your modules use the 3.x series of the aws provider.

# Use an override file to lock the provider version, regardless of if required_providers is defined in the modules.
generate "provider_version" {
  path      = "provider_version_override.tf"
  if_exists = "overwrite_terragrunt"
  contents  = <<EOF
terraform {
  required_providers {
    aws = {
      source  = "hashicorp/aws"
      version = "~> 3.0"
    }
  }
}
EOF
}

Note that you may have to remove the .terraform.lock.hcl file to ensure terraform downloads the proper provider version.