#658 stateless code sandbox Pull request opened by samhita-alla Add

flyte.sandbox.create()

for containerized execution This PR introduces a lightweight sandbox runtime for executing arbitrary code inside an ephemeral stateless container, along with improvements to file handling. Sandbox execution API

flyte.sandbox.create()

runs arbitrary Python code or shell commands inside a one-off Docker container. The container is built on demand from the declared

packages

/

system_packages

, executed once, and discarded. Supported execution modes Auto-IO mode (default): minimal boilerplate • Triggered when

code

is provided and

auto_io=True

• Flyte auto-generates an argparse preamble • Declared inputs become local variables • Declared scalar outputs are written automatically to

/var/outputs/

• No manual I/O handling required sandbox = flyte.sandbox.create( name="double", code="result = x * 2", inputs={"x": int}, outputs={"result": int}, ) result = await sandbox.run.aio(x=21) # -> 42 Verbatim mode: full script control • Triggered when code is provided and

auto_io=False

• Script runs exactly as written • No CLI args injected • Script handles all I/O manually via

/var/inputs/

and

/var/outputs/

sandbox = flyte.sandbox.create( name="etl", code=""" import json, pathlib data = json.loads(pathlib.Path("/var/inputs/payload").read_text()) pathlib.Path("/var/outputs/total").write_text( str(sum(data["values"])) ) """, inputs={"payload": File}, outputs={"total": int}, auto_io=False, ) Command mode: run arbitrary commands • Triggered when command is provided • Executes any binary, shell pipeline, or test runner sandbox = flyte.sandbox.create( name="test-runner", command=["/bin/bash", "-c", pytest_cmd], arguments=["_", "/var/inputs/solution.py", "/var/inputs/tests.py"], inputs={"solution.py": File, "tests.py": File}, outputs={"exit_code": str}, ) Execution Call

.run()

on the returned sandbox to build the image and execute. Container improvements (

_container.py

) • Adds support for parsing

File

input from

kwargs

Deterministic remote file paths (

_file.py

) -

File.named_remote(name)

Creates a File reference whose remote path is derived deterministically from name. Unlike

File.new_remote()

, which generates a random path on each call, this method produces the same path for the same name within a task execution, making it safe across retries. • First attempt uploads to the path • Retries resolve to the identical location • Avoids duplicate uploads If extraction fails, it falls back to the run base directory. file = File.named_remote("report.csv") async with file.open("wb") as f: await f.write(b"...") New error type `InvalidPackageError`: Introduced to signal invalid or unavailable packages during sandbox image build. flyteorg/flyte-sdk