push_file_to_sandbox

Copy files from your local system to a Modal sandbox environment for uploading inputs, transferring configurations, or deploying code to isolated cloud-based Python environments.

Instructions

Copies a file from the local filesystem to a Modal sandbox. Parameters: - sandbox_id: The unique identifier of the sandbox - local_path: Path to the source file on local filesystem - sandbox_path: Destination path in the sandbox - read_file_mode: Optional mode for reading local file (default: "rb") - writefile_mode: Optional mode for writing to sandbox (default: "wb") Returns a PushFileToSandboxResponse containing: - success: Boolean indicating if copy was successful - message: Descriptive message about the copy operation - local_path: The source path on local filesystem - sandbox_path: The destination path in sandbox - file_size: Size of the file in bytes This tool is useful for: - Uploading input files to sandboxes - Transferring configuration files - Setting up sandbox environments - Deploying code to sandboxes The tool will: 1. Verify sandbox is running and local file exists 2. Read contents from local file 3. Write contents to sandbox path 4. Return status of the operation

Input Schema

TableJSON Schema

Name	Required	Default
`sandbox_id`	Yes
`local_path`	Yes
`sandbox_path`	Yes
`read_file_mode`	No	rb
`writefile_mode`	No	wb

Implementation Reference

src/mcp4modal_sandbox/backend/mcp_server.py:318-356 (handler)
The handler function that implements the push_file_to_sandbox tool logic: reads local file content and writes it to the sandbox using a thread executor.
async def push_file_to_sandbox( self, sandbox_id: str, local_path: str, sandbox_path: str, read_file_mode: str = "rb", writefile_mode: str = "wb" ) -> PushFileToSandboxResponse: # Get sandbox from Modal using from_id modal_sandbox = await modal.Sandbox.from_id.aio(sandbox_id) # Check if sandbox is running before copying file sandbox_status = await modal_sandbox.poll.aio() if sandbox_status is not None: raise ToolError(f"Sandbox {sandbox_id} is not running") if not path.exists(local_path): raise ToolError(f"Local file {local_path} does not exist") # Get file size file_size = os.path.getsize(local_path) # Read local file asynchronously async with aiofiles.open(local_path, read_file_mode) as file_pointer: content = await file_pointer.read() # Write to sandbox using thread executor await self._write_sandbox_file_in_thread(modal_sandbox, sandbox_path, content, writefile_mode) logger.info(f"Copied file from {local_path} to {sandbox_path} in sandbox {sandbox_id}") return PushFileToSandboxResponse( success=True, message=f"File copied successfully to {sandbox_path}", local_path=local_path, sandbox_path=sandbox_path, file_size=file_size, )
src/mcp4modal_sandbox/backend/response_schema.py:49-55 (schema)
Pydantic model defining the response schema for the push_file_to_sandbox tool.
class PushFileToSandboxResponse(BaseModel): success: bool message: str local_path: str sandbox_path: str file_size: int
src/mcp4modal_sandbox/backend/mcp_server.py:121-125 (registration)
Registration of the push_file_to_sandbox tool with the FastMCP server.
mcp_app.tool( name="push_file_to_sandbox", description=ToolDescriptions.PUSH_FILE_TO_SANDBOX, )(self.push_file_to_sandbox)
src/mcp4modal_sandbox/backend/mcp_server.py:92-98 (helper)
Helper function used by the handler to write file content to the sandbox in a synchronous manner via thread pool executor.
async def _write_sandbox_file_in_thread(self, modal_sandbox, file_path: str, content, mode: str = 'wb'): def _sync_write(): with modal_sandbox.open(file_path, mode) as f: f.write(content) loop = asyncio.get_event_loop() return await loop.run_in_executor(self.thread_pool_executor, _sync_write)

MCP4Modal Sandbox