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AWS Terraform MCP Server

by stv-io

ExecuteTerragruntCommand

Run Terragrunt commands to manage AWS infrastructure with Terraform, handling remote state, module dependencies, and multi-module operations.

Instructions

Execute Terragrunt workflow commands against an AWS account.

This tool runs Terragrunt commands (init, plan, validate, apply, destroy, run-all) in the
specified working directory, with optional variables and region settings. Terragrunt extends
Terraform's functionality by providing features like remote state management, dependencies
between modules, and the ability to execute Terraform commands on multiple modules at once.

Parameters:
    command: Terragrunt command to execute
    working_directory: Directory containing Terragrunt files
    variables: Terraform variables to pass
    aws_region: AWS region to use
    strip_ansi: Whether to strip ANSI color codes from output
    include_dirs: Directories to include in a multi-module run
    exclude_dirs: Directories to exclude from a multi-module run
    run_all: Run command on all modules in subdirectories
    terragrunt_config: Path to a custom terragrunt config file (not valid with run-all)

Returns:
    A TerragruntExecutionResult object containing command output and status

Input Schema

TableJSON Schema
NameRequiredDescriptionDefault
commandYesTerragrunt command to execute
working_directoryYesDirectory containing Terragrunt files
variablesNoTerraform variables to pass
aws_regionNoAWS region to use
strip_ansiNoWhether to strip ANSI color codes from output
include_dirsNoDirectories to include in a multi-module run
exclude_dirsNoDirectories to exclude from a multi-module run
run_allNoRun command on all modules in subdirectories
terragrunt_configNoPath to a custom terragrunt config file (not valid with run-all)

Implementation Reference

  • Main handler function that implements the Terragrunt command execution logic, including security checks, command building, subprocess execution, output processing, and result formatting.
    async def execute_terragrunt_command_impl(
        request: TerragruntExecutionRequest,
    ) -> TerragruntExecutionResult:
        """Execute Terragrunt workflow commands against an AWS account.
    
        This tool runs Terragrunt commands (init, plan, validate, apply, destroy, run-all) in the
        specified working directory, with optional variables and region settings.
    
        Parameters:
            request: Details about the Terragrunt command to execute
    
        Returns:
            A TerragruntExecutionResult object containing command output and status
        """
        logger.info(f"Executing 'terragrunt {request.command}' in {request.working_directory}")
    
        # Helper function to clean output text
        def clean_output_text(text: str) -> str:
            """Clean output text by removing or replacing problematic Unicode characters.
    
            Args:
                text: The text to clean
    
            Returns:
                Cleaned text with ASCII-friendly replacements
            """
            if not text:
                return text
    
            # First remove ANSI escape sequences (color codes, cursor movement)
            ansi_escape = re.compile(r'\x1B(?:[@-Z\\-_]|\[[0-?]*[ -/]*[@-~])')
            text = ansi_escape.sub('', text)
    
            # Remove C0 and C1 control characters (except common whitespace)
            control_chars = re.compile(r'[\x00-\x08\x0B-\x0C\x0E-\x1F\x7F-\x9F]')
            text = control_chars.sub('', text)
    
            # Replace HTML entities
            html_entities = {
                '->': '->',  # Replace HTML arrow
                '<': '<',  # Less than
                '>': '>',  # Greater than
                '&': '&',  # Ampersand
            }
            for entity, replacement in html_entities.items():
                text = text.replace(entity, replacement)
    
            # Replace box-drawing and other special Unicode characters with ASCII equivalents
            unicode_chars = {
                '\u2500': '-',  # Horizontal line
                '\u2502': '|',  # Vertical line
                '\u2514': '+',  # Up and right
                '\u2518': '+',  # Up and left
                '\u2551': '|',  # Double vertical
                '\u2550': '-',  # Double horizontal
                '\u2554': '+',  # Double down and right
                '\u2557': '+',  # Double down and left
                '\u255a': '+',  # Double up and right
                '\u255d': '+',  # Double up and left
                '\u256c': '+',  # Double cross
                '\u2588': '#',  # Full block
                '\u25cf': '*',  # Black circle
                '\u2574': '-',  # Left box drawing
                '\u2576': '-',  # Right box drawing
                '\u2577': '|',  # Down box drawing
                '\u2575': '|',  # Up box drawing
            }
            for char, replacement in unicode_chars.items():
                text = text.replace(char, replacement)
    
            return text
    
        # Set environment variables for AWS region if provided
        env = os.environ.copy()
        if request.aws_region:
            env['AWS_REGION'] = request.aws_region
    
        # Security check for command injection
        allowed_commands = ['init', 'plan', 'validate', 'apply', 'destroy', 'output', 'run-all']
        if request.command not in allowed_commands:
            logger.error(f'Invalid Terragrunt command: {request.command}')
            return TerragruntExecutionResult(
                command=f'terragrunt {request.command}',
                status='error',
                error_message=f'Invalid Terragrunt command: {request.command}. Allowed commands are: {", ".join(allowed_commands)}',
                working_directory=request.working_directory,
                outputs=None,
                affected_dirs=None,
            )
    
        # Validate that terragrunt_config is not used with run-all
        if request.terragrunt_config and request.command == 'run-all':
            logger.error('terragrunt_config cannot be used with run-all command')
            return TerragruntExecutionResult(
                command=f'terragrunt {request.command}',
                status='error',
                error_message='Invalid configuration: --terragrunt-config cannot be used with run-all command',
                working_directory=request.working_directory,
                outputs=None,
                affected_dirs=None,
            )
    
        # Check for potentially dangerous characters or command injection attempts
        dangerous_patterns = get_dangerous_patterns()
        logger.debug(f'Checking for {len(dangerous_patterns)} dangerous patterns')
    
        for pattern in dangerous_patterns:
            if request.variables:
                # Check if the pattern is in any of the variable values
                for var_name, var_value in request.variables.items():
                    if pattern in str(var_value) or pattern in str(var_name):
                        logger.error(
                            f'Potentially dangerous pattern detected in variable {var_name}: {pattern}'
                        )
                        return TerragruntExecutionResult(
                            command=f'terragrunt {request.command}',
                            status='error',
                            error_message=f"Security violation: Potentially dangerous pattern '{pattern}' detected in variable '{var_name}'",
                            working_directory=request.working_directory,
                            outputs=None,
                            affected_dirs=None,
                        )
    
            # Check terragrunt_config for dangerous patterns
            if request.terragrunt_config and pattern in str(request.terragrunt_config):
                logger.error(f'Potentially dangerous pattern detected in terragrunt_config: {pattern}')
                return TerragruntExecutionResult(
                    command=f'terragrunt {request.command}',
                    status='error',
                    error_message=f"Security violation: Potentially dangerous pattern '{pattern}' detected in terragrunt_config",
                    working_directory=request.working_directory,
                    outputs=None,
                    affected_dirs=None,
                )
    
            # Also check include_dirs and exclude_dirs for dangerous patterns
            if request.include_dirs:
                for dir_path in request.include_dirs:
                    if pattern in str(dir_path):
                        logger.error(
                            f'Potentially dangerous pattern detected in include_dirs: {pattern}'
                        )
                        return TerragruntExecutionResult(
                            command=f'terragrunt {request.command}',
                            status='error',
                            error_message=f"Security violation: Potentially dangerous pattern '{pattern}' detected in include_dirs",
                            working_directory=request.working_directory,
                            outputs=None,
                            affected_dirs=None,
                        )
    
            if request.exclude_dirs:
                for dir_path in request.exclude_dirs:
                    if pattern in str(dir_path):
                        logger.error(
                            f'Potentially dangerous pattern detected in exclude_dirs: {pattern}'
                        )
                        return TerragruntExecutionResult(
                            command=f'terragrunt {request.command}',
                            status='error',
                            error_message=f"Security violation: Potentially dangerous pattern '{pattern}' detected in exclude_dirs",
                            working_directory=request.working_directory,
                            outputs=None,
                            affected_dirs=None,
                        )
    
        # Build the command
        base_cmd = ['terragrunt']
    
        # Handle run-all command differently
        if request.command == 'run-all':
            base_cmd.append('run-all')
            # The actual terraform command becomes the first argument
            # Default to 'apply' if not specified in the command
            base_cmd.append('apply')
        else:
            base_cmd.append(request.command)
    
        # Add auto-approve flag for apply and destroy commands to make them non-interactive
        if request.command in ['apply', 'destroy'] or (request.command == 'run-all'):
            logger.info(f'Adding -auto-approve flag to {request.command} command')
            base_cmd.append('-auto-approve')
    
        # Add terragrunt_config if specified and not using run-all
        if request.terragrunt_config:
            logger.info(f'Using custom terragrunt config file: {request.terragrunt_config}')
            base_cmd.append(f'--terragrunt-config={request.terragrunt_config}')
    
        # Add variables only for commands that accept them (plan, apply, destroy, output)
        if request.command in ['plan', 'apply', 'destroy', 'output', 'run-all'] and request.variables:
            logger.info(f'Adding {len(request.variables)} variables to {request.command} command')
            for key, value in request.variables.items():
                base_cmd.append(f'-var={key}={value}')
    
        # Add include-dirs if specified
        if request.include_dirs and request.command == 'run-all':
            for dir_path in request.include_dirs:
                base_cmd.append(f'--queue-include-dir={dir_path}')
    
        # Add exclude-dirs if specified
        if request.exclude_dirs and request.command == 'run-all':
            for dir_path in request.exclude_dirs:
                base_cmd.append(f'--queue-exclude-dir={dir_path}')
    
        # Execute command
        try:
            process = subprocess.run(
                base_cmd, cwd=request.working_directory, capture_output=True, text=True, env=env
            )
    
            # Prepare the result
            stdout = process.stdout
            stderr = process.stderr if process.stderr else ''
    
            # Clean output text if requested
            if request.strip_ansi:
                logger.debug('Cleaning command output text (ANSI codes and control characters)')
                stdout = clean_output_text(stdout)
                stderr = clean_output_text(stderr)
    
            # Extract affected directories for run-all command
            affected_dirs = None
            if request.command == 'run-all':
                affected_dirs = []
                # Look for directory paths in the output
                dir_pattern = re.compile(r'Module at\s+"([^"]+)"')
                for match in dir_pattern.finditer(stdout):
                    affected_dirs.append(match.group(1))
    
            result = {
                'command': f'terragrunt {request.command}',
                'status': 'success' if process.returncode == 0 else 'error',
                'return_code': process.returncode,
                'stdout': stdout,
                'stderr': stderr,
                'working_directory': request.working_directory,
                'outputs': None,
                'affected_dirs': affected_dirs,
            }
    
            # Get outputs if this was a successful apply or output command
            if (
                request.command in ['apply', 'output'] or (request.command == 'run-all')
            ) and process.returncode == 0:
                try:
                    logger.info('Getting Terragrunt outputs')
                    output_process = subprocess.run(
                        ['terragrunt', 'output', '-json'],
                        cwd=request.working_directory,
                        capture_output=True,
                        text=True,
                        env=env,
                    )
    
                    if output_process.returncode == 0 and output_process.stdout:
                        # Get output and clean it if needed
                        output_stdout = output_process.stdout
                        if request.strip_ansi:
                            output_stdout = clean_output_text(output_stdout)
    
                        # Parse the JSON output
                        raw_outputs = json.loads(output_stdout)
    
                        # Process outputs to extract values from complex structure
                        processed_outputs = {}
                        for key, value in raw_outputs.items():
                            # Terraform outputs in JSON format have a nested structure
                            # with 'value', 'type', and sometimes 'sensitive'
                            if isinstance(value, dict) and 'value' in value:
                                processed_outputs[key] = value['value']
                            else:
                                processed_outputs[key] = value
    
                        result['outputs'] = processed_outputs
                        logger.info(f'Extracted {len(processed_outputs)} Terragrunt outputs')
                except Exception as e:
                    logger.warning(f'Failed to get Terragrunt outputs: {e}')
    
            # Return the output
            return TerragruntExecutionResult(**result)
        except Exception as e:
            return TerragruntExecutionResult(
                command=f'terragrunt {request.command}',
                status='error',
                error_message=str(e),
                working_directory=request.working_directory,
                outputs=None,
                affected_dirs=None,
            )
  • MCP tool registration with @mcp.tool decorator, defines input parameters with descriptions, creates request model, and delegates to impl.
    @mcp.tool(name='ExecuteTerragruntCommand')
    async def execute_terragrunt_command(
        command: Literal['init', 'plan', 'validate', 'apply', 'destroy', 'output', 'run-all'] = Field(
            ..., description='Terragrunt command to execute'
        ),
        working_directory: str = Field(..., description='Directory containing Terragrunt files'),
        variables: Optional[Dict[str, str]] = Field(None, description='Terraform variables to pass'),
        aws_region: Optional[str] = Field(None, description='AWS region to use'),
        strip_ansi: bool = Field(True, description='Whether to strip ANSI color codes from output'),
        include_dirs: Optional[List[str]] = Field(
            None, description='Directories to include in a multi-module run'
        ),
        exclude_dirs: Optional[List[str]] = Field(
            None, description='Directories to exclude from a multi-module run'
        ),
        run_all: bool = Field(False, description='Run command on all modules in subdirectories'),
        terragrunt_config: Optional[str] = Field(
            None, description='Path to a custom terragrunt config file (not valid with run-all)'
        ),
    ) -> TerragruntExecutionResult:
        """Execute Terragrunt workflow commands against an AWS account.
    
        This tool runs Terragrunt commands (init, plan, validate, apply, destroy, run-all) in the
        specified working directory, with optional variables and region settings. Terragrunt extends
        Terraform's functionality by providing features like remote state management, dependencies
        between modules, and the ability to execute Terraform commands on multiple modules at once.
    
        Parameters:
            command: Terragrunt command to execute
            working_directory: Directory containing Terragrunt files
            variables: Terraform variables to pass
            aws_region: AWS region to use
            strip_ansi: Whether to strip ANSI color codes from output
            include_dirs: Directories to include in a multi-module run
            exclude_dirs: Directories to exclude from a multi-module run
            run_all: Run command on all modules in subdirectories
            terragrunt_config: Path to a custom terragrunt config file (not valid with run-all)
    
        Returns:
            A TerragruntExecutionResult object containing command output and status
        """
        request = TerragruntExecutionRequest(
            command=command,
            working_directory=working_directory,
            variables=variables,
            aws_region=aws_region,
            strip_ansi=strip_ansi,
            include_dirs=include_dirs,
            exclude_dirs=exclude_dirs,
            run_all=run_all,
            terragrunt_config=terragrunt_config,
        )
        return await execute_terragrunt_command_impl(request)
  • Pydantic models for input (TerragruntExecutionRequest) and output (TerragruntExecutionResult) schema validation and type definitions.
    class TerragruntExecutionRequest(BaseModel):
        """Request model for Terragrunt command execution with parameters.
    
        Attributes:
            command: The Terragrunt command to execute (init, plan, validate, apply, destroy, etc.).
            working_directory: Directory containing Terragrunt configuration files.
            variables: Optional dictionary of Terraform variables to pass.
            aws_region: Optional AWS region to use.
            strip_ansi: Whether to strip ANSI color codes from command output.
            include_dirs: Optional list of directories to include in a multi-module run.
            exclude_dirs: Optional list of directories to exclude from a multi-module run.
            run_all: Whether to run the command in all subdirectories with terragrunt.hcl files.
        """
    
        command: Literal['init', 'plan', 'validate', 'apply', 'destroy', 'output', 'run-all'] = Field(
            ..., description='Terragrunt command to execute'
        )
        working_directory: str = Field(..., description='Directory containing Terragrunt files')
        variables: Optional[Dict[str, str]] = Field(None, description='Terraform variables to pass')
        aws_region: Optional[str] = Field(None, description='AWS region to use')
        strip_ansi: bool = Field(True, description='Whether to strip ANSI color codes from output')
        include_dirs: Optional[List[str]] = Field(
            None, description='Directories to include in a multi-module run'
        )
        exclude_dirs: Optional[List[str]] = Field(
            None, description='Directories to exclude from a multi-module run'
        )
        run_all: bool = Field(False, description='Run command on all modules in subdirectories')
        terragrunt_config: Optional[str] = Field(
            None, description='Path to a custom terragrunt config file (not valid with run-all)'
        )
    
    
    class TerragruntExecutionResult(BaseModel):
        """Result model for Terragrunt command execution.
    
        Attributes:
            command: The Terragrunt command that was executed.
            status: Execution status (success/error).
            return_code: The command's return code (0 for success).
            stdout: Standard output from the Terragrunt command.
            stderr: Standard error output from the Terragrunt command.
            working_directory: Directory where the command was executed.
            error_message: Optional error message if execution failed.
            outputs: Dictionary of output values from Terragrunt (for apply command).
            affected_dirs: List of directories affected by a run-all command.
        """
    
        command: str
        status: Literal['success', 'error']
        return_code: Optional[int] = None
        stdout: Optional[str] = None
        stderr: str = ''
        working_directory: str
        error_message: Optional[str] = None
        outputs: Optional[Dict[str, Any]] = Field(
            None, description='Terragrunt outputs (for apply or output command)'
        )
        affected_dirs: Optional[List[str]] = Field(
            None, description='Directories affected by a run-all command'
        )

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