terraform_validate hook doesn't run terraform init if a provider is not installed even when using --retry-once-with-cleanup=true

[fwolfheimer]

Describe the bug

In a situation where the Terraform providers are not installed the terraform_validate hook doesn't execute terraform init to install the providers even if the hook is configured with the option --retry-once-with-cleanup=true. I ran in a situation where the terraform_validate hook terminated with an error showing the following error output (from Terraform apparently):

Validation failed: my-project
{
  "format_version": "1.0",
  "valid": false,
  "error_count": 6,
  "warning_count": 0,
  "diagnostics": [
    {
      "severity": "error",
      "summary": "Missing required provider",
      "detail": "This configuration requires provider registry.terraform.io/hashicorp/external, but that provider isn't available. You may be able to install it automatically by running:
  terraform init"
    },
    {
      "severity": "error",
      "summary": "Missing required provider",
      "detail": "This configuration requires provider registry.terraform.io/hashicorp/google, but that provider isn't available. You may be able to install it automatically by running:
  terraform init"
    },
    {
      "severity": "error",
      "summary": "Missing required provider",
      "detail": "This configuration requires provider registry.terraform.io/hashicorp/null, but that provider isn't available. You may be able to install it automatically by running:
  terraform init"
    },
    {
      "severity": "error",
      "summary": "Missing required provider",
      "detail": "This configuration requires provider registry.terraform.io/hashicorp/random, but that provider isn't available. You may be able to install it automatically by running:
  terraform init"
    },
    {
      "severity": "error",
      "summary": "Missing required provider",
      "detail": "This configuration requires provider registry.terraform.io/hashicorp/tls, but that provider isn't available. You may be able to install it automatically by running:
  terraform init"
    },
    {
      "severity": "error",
      "summary": "Missing required provider",
      "detail": "This configuration requires provider registry.terraform.io/techbeck03/guacamole, but that provider isn't available. You may be able to install it automatically by running:
  terraform init"
    }
  ]
}

The problem is that the function match_validate_errors in the terraform_validate.sh script doesn't have the error Missing required provider in its list of errors for which terraform init should be called to fix them.

How can we reproduce it?

Use it with a fresh TF config where no provider has been installed, yet.

[antonbabenko]

This issue has been resolved in version 1.83.6 🎉