Summary

This PR refactors the terragrunt module to explicitly separate terragrunt-specific arguments from terraform command arguments, improving API clarity and usability.

Motivation

The previous implementation used a single ExtraArgs field for all arguments, making it unclear which arguments were for terragrunt vs terraform. The -- separator logic was also handled inconsistently across different commands.

Changes

• Options struct refactoring: Replaced single ExtraArgs field with:
  • TerragruntArgs: For terragrunt-specific flags (e.g., --no-color, --terragrunt-log-level)
  • TerraformArgs: For terraform commands passed after -- separator (e.g., plan, apply, -upgrade)
• Automatic separator handling: The -- separator is now automatically added when TerraformArgs are present
• Test updates: All tests updated to use the new argument structure

Benefits

• ✅ Clear separation of concerns between terragrunt and terraform arguments
• ✅ Automatic handling of -- separator reduces boilerplate
• ✅ Better type safety - prevents accidental mixing of argument types
• ✅ More intuitive and maintainable API

Testing

All existing tests have been updated and are passing:

go test ./modules/terragrunt -v
# PASS
# ok github.com/gruntwork-io/terratest/modules/terragrunt

Breaking Changes

This is a breaking change for the beta terragrunt module. Users will need to update their code to use TerragruntArgs and TerraformArgs instead of ExtraArgs.

Migration Example

Before:

options := &terragrunt.Options{
    TerragruntDir: "/path/to/config",
    ExtraArgs: []string{"--no-color", "plan", "-out=tfplan"},
}

After:

options := &terragrunt.Options{
    TerragruntDir: "/path/to/config",
    TerragruntArgs: []string{"--no-color"},
    TerraformArgs: []string{"plan", "-out=tfplan"},
}