Async P4Runtime/gNMI Framework
Project description
🐟 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.
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