useshards

The Python SDK for shard, the sandbox manager. Shard is for blocking code and AsyncShard is for asyncio. Both have the same verbs.

pip install useshards

To run the code on main instead, install it from the repository:

pip install "useshards @ git+https://github.com/presmihaylov/shard#subdirectory=sdks/python"

Python 3.11 or later. The runtime dependencies are HTTPX, attrs and typing-extensions.

Connect

The SDK talks to shard serve over HTTPS, or over HTTP on localhost or a trusted encrypted network, where it warns once per client as the CLI does. Mint a key on the host with shard tokens mint, then:

export SHARD_REMOTE=https://shard.example.com
export SHARD_API_KEY=<the token>

An argument beats the environment: Shard(remote=..., api_key=...). ca_file= (or SHARD_CA_FILE) trusts a private CA, for an https remote only. A remote with no port takes 443 for https and 80 for http.

Quickstart

from useshards import Shard

with Shard() as shard:
    sandbox = shard.create("docker.io/library/alpine:3")
    try:
        result = sandbox.exec(["uname", "-sr"])
        print(result.exit_code, result.stdout)

        sandbox.files.write("/tmp/hello.txt", "hello\n")
        print(sandbox.exec("cat /tmp/hello.txt").stdout)
    finally:
        sandbox.remove(force=True)

The same on asyncio:

import asyncio
from useshards import AsyncShard

async def main() -> None:
    async with AsyncShard() as shard:
        sandbox = await shard.create("docker.io/library/alpine:3")
        try:
            results = await asyncio.gather(*(sandbox.exec(f"echo {n}") for n in range(3)))
            print([r.stdout for r in results])
        finally:
            await sandbox.remove(force=True)

asyncio.run(main())

examples/ has both in full. Set SHARD_REMOTE and SHARD_API_KEY, then run python examples/quickstart.py.

What to know

• create() runs no command. It returns a running sandbox, or one in state failed with info.failed_reason. Run commands in it with exec().
• A sandbox outlives its app. shard.run(image, command) returns an App. When the app exits, its sandbox stays running, so you can still exec into it. Only stop() or remove() ends it.
• A string command runs under /bin/sh -c. A list runs as it is.
• exec(..., background=True) returns a Command. wait(), kill(), write_stdin(), close_stdin() and resize() act on it. commands.get(id) finds it again from another client. In the foreground stdin= is the whole input; in the background stdin=True keeps the input open for write_stdin().
• A cancel never kills the remote command. An asyncio cancel, a timeout or a dropped connection ends only the wait. The command runs on until it exits or you call kill().
• Output may hold only its end. A result keeps the newest 8 MiB of stdout and stderr together (output_limit_bytes=, 0 keeps none). on_stdout= and on_stderr= see every chunk as it arrives. result.lost_bytes is different: it counts output the daemon dropped before any client read it. logs() is bounded on the daemon too, so a long app may hold only its end.
• Files stream. files.download() writes to a temporary file and renames it at the end, so a large file never sits in memory. An upload sends its length first: files.upload() takes a path, and files.write() takes bytes, a seekable file, or a stream with size=.
• A verb the provider lacks raises UnsupportedError. shard.capabilities() says which of the eight lifecycle verbs the daemon's provider supports (create, start, stop, remove, pause, resume, fork and snapshot), before you call them.

Lists

shard.list() returns SandboxList(sandboxes, warnings). shard.secrets.list() returns SecretList(secrets, warnings). The async client returns the same result types. The warnings name entries the daemon could not read. Both lists collect warnings from every page, keeping each exact text once in first-seen order. Check them before you treat the result as complete. Other lists return plain lists.

Errors

ShardError is the base of every exception below, which covers the daemon, the transport and the settings. A bad local argument raises the native exception instead: an upload of a missing file raises FileNotFoundError, and create() with neither an image nor a snapshot raises ValueError.

ProtocolError is an answer the SDK cannot read, UnknownLengthError an upload of unknown size or one whose source changed size while it was sent, and UnsafeArchiveError a download_dir tar entry the SDK refuses to land, as one outside the destination, named by entry and reason. A non-zero exit code is not an exception. Read result.exit_code.

An APIError can carry holders, the sandbox ids that prevent an operation such as secret removal. The attribute is None when the error has no holders field.

License

Apache-2.0.