finsy 0.7.0

P4Runtime Client Library

🐟 Finsy P4Runtime Library

Finsy is a P4Runtime controller library written in Python using asyncio. Finsy includes support for gNMI.

import asyncio
import finsy as fy

async def main():
    async with fy.Switch("sw1", "127.0.0.1:50001") as sw1:
        print(sw1.p4info)

asyncio.run(main())

Multiple Switches

With Finsy, you can write a P4Runtime controller that manages multiple switches.

Each switch is managed by an async ready_handler function. Your ready_handler function can read or update various P4Runtime entities in the switch. It can also create tasks to listen for packets or digests.

When you write P4Runtime updates to the switch, you use a unary operator (+, -, ~) to specify the operation: INSERT (+), DELETE (-) or MODIFY (~).

async def ready_handler(sw: fy.Switch):
    await sw.delete_all()
    await sw.write(
        [
            # Insert multicast group with ports 1, 2, 3 and CONTROLLER.
            +fy.P4MulticastGroupEntry(1, replicas=[1, 2, 3, 255]),
            # Modify default table entry to flood all unmatched packets.
            ~fy.P4TableEntry(
                "ipv4",
                action=fy.P4TableAction("flood"),
                is_default_action=True,
            ),
        ]
    )

    async for packet in sw.read_packets():
        print(f"{sw.name}: {packet}")

Use the SwitchOptions class to specify each switch's settings, including the p4info/p4blob and ready_handler. Use the Controller class to drive multiple switch connections. Each switch will call back into your ready_handler function after the P4Runtime connection is established.

from pathlib import Path

options = fy.SwitchOptions(
    p4info=Path("hello.p4info.txt"),
    p4blob=Path("hello.json"),
    ready_handler=ready_handler,
)

controller = fy.Controller([
    fy.Switch("sw1", "127.0.0.1:50001", options),
    fy.Switch("sw2", "127.0.0.1:50002", options),
    fy.Switch("sw3", "127.0.0.1:50003", options),
])

asyncio.run(controller.run())

If the switch disconnects or its role changes to backup, the task running your ready_handler (and any tasks it spawned) will be cancelled and the ready_handler will begin again.

For more examples, see the examples directory.