sw-serverless

Write SW-Serverless adapters in Python 3.12 or later. The package has no dependencies: it speaks the host's protocol — gRPC over a Unix socket — with the standard library alone, so it vendors into an adapter package as plain files, for any platform.

import sw_serverless as sw


class Greeter:
    def __init__(self):
        sw.expect("Greeting", "Hello", description="What to say")
        sw.expect("ApiKey", secret=True)

    @sw.command(description="Greets someone")
    def greet(self, name: str) -> str:
        return f"{sw.value_of('Greeting')}, {name}"


if __name__ == "__main__":
    sw.run(Greeter)

• Settings are declared with sw.expect(name, default=None, *, required, secret, description, type) and read with sw.value_of(name): the call's own properties, then the values the adapter was started with, then the default.
• Commands are methods marked @sw.command(name, description=...). A command takes at most one argument. A str argument or result is raw text, bytes are passed as they are, and anything else is JSON; a dataclass is read from and written as a JSON object. Commands may be sync or async; sync ones run on a worker thread.
• Errors raised by a command reach the caller with their type and message. Raise sw.AdapterError(message, type="Acme.Rejected") to choose the type.
• Resident adapters have a start method and run until stopped, with optional stop, status (returns connected, state, details…) and reset(session_id). In a command, sw.context() publishes events (await ctx.publish(...)), keeps small state (get_state/set_state/delete_state) and records metrics.
• Logging through Python's logging reaches the host.
• python main.py --describe prints what the adapter is; sw-serverless build writes it into the manifest.

An application with a contract of its own declares it with @sw.implements("orders", 1, "processor") on the adapter class, and can give its adapter authors base classes that do it for them. sw-serverless init --lang python starts an adapter.

Tests: PYTHONPATH=src python -m unittest discover -s tests.