Volume io

volume_io

Streaming helpers for moving files in and out of a transient Modal volume

Additional Information

• Both the server and the Modal container runtime use the helpers defined here to copy files into or out of a transient per-job ephemeral Modal Volume

• This volume is what allows the container to access local files for processing and send back processed files for the server to save locally

• Each transfer is streamed in chunks and reported through a themed transfer bar, so neither side ever loads a whole multi-GB media file into memory

• See the modal_processing.worker module for more information on this

download_from_volume(volume, vol_fp, local_path, *, desc=None)

Copies the vol_fp file out of a Modal.Volume to local_path

The file is read from the volume in chunks (never loaded whole into memory) while a themed transfer bar reports the progress. The destination's parent directory is created if missing. The stream lands on a uniquely named temporary sibling and is atomically renamed into place, so a reader (and the Modal-host volume syncer) never sees a partially written file. The temporary is removed on failure

Parameters:

Name	Type	Description	Default
volume	Volume	The volume to read from	required
vol_fp	str	The file's path inside the volume	required
local_path	str | PathLike[str]	The local destination file	required
desc	str | None	Optional bar label. Defaults to f"Downloading {vol_fp} From Volume"	None

Returns:

Type	Description
Path	The local destination path

Raises:

Type	Description
ModalVolumeError	If the download fails

upload_to_volume(volume, local_path, vol_fp, *, desc=None)

Stream a local file into a Modal.Volume under the vol_fp key

The file is read from disk in chunks (never loaded whole into memory) while a themed transfer bar reports the progress

Parameters:

Name	Type	Description	Default
volume	Volume	The modal volume to upload into	required
local_path	str | PathLike[str]	The local file to upload	required
vol_fp	str	The destination path inside the volume	required
desc	str | None	Optional bar label. Defaults to f"Uploading {name} To Volume"	None

Raises:

Type	Description
ModalVolumeError	If the source is missing or the upload fails