hawkapi-websockets

WebSocket utilities for HawkAPI. Connection manager with rooms + broadcasting, optional Redis pub/sub backplane for multi-process fan-out, and a heartbeat monitor.

Install

pip install hawkapi-websockets                # local-only (single-process)
pip install 'hawkapi-websockets[redis]'       # + Redis backplane

Quickstart

from hawkapi import Depends, HawkAPI, WebSocket
from hawkapi_websockets import ConnectionManager, get_manager, init_websockets

app = HawkAPI()
init_websockets(app)


@app.websocket("/ws/{room}")
async def ws_room(websocket: WebSocket, room: str, m: ConnectionManager = Depends(get_manager)):
    await websocket.accept()
    conn = await m.connect(websocket, rooms=[room])
    try:
        await m.broadcast_json({"event": "joined", "id": conn.id}, room=room)
        async for msg in websocket.iter_text():
            await m.broadcast_text(msg, room=room, exclude=[conn.id])
    finally:
        await m.disconnect(conn.id)
        await m.broadcast_json({"event": "left", "id": conn.id}, room=room)

Authentication & Security

WebSockets bypass CORS, so the browser's same-origin protections do not apply. A page on any site can open a WebSocket to your server and ride the user's cookies (Cross-Site WebSocket Hijacking, CSWSH). This library is secure-by-default where it can be and provides hooks where enforcement has to live in your app.

Validate the Origin (CSWSH)

Pass allowed_origins and call check_origin before accept():

m = ConnectionManager(allowed_origins={"https://app.example.com"})
# or: init_websockets(app, allowed_origins={"https://app.example.com"})


@app.websocket("/ws/{room}")
async def ws_room(websocket, room, m=Depends(get_manager)):
    if not m.check_origin(websocket):
        await websocket.close(code=4403)  # forbidden
        return
    await websocket.accept()
    ...

When allowed_origins is None (the default) check_origin returns True and performs no validation — you are responsible for enforcing it out of band. Leaving it unset on a cookie-authenticated endpoint exposes you to CSWSH.

Authenticate the connection

Provide an on_connect hook. It runs inside connect() before the connection is tracked; return False (or raise) to reject — connect() raises PermissionError. Authenticate with a token sent in a header (e.g. Authorization / Sec-WebSocket-Protocol), never in the query string — query strings leak into logs, referrers, and proxies.

async def authenticate(websocket, metadata: dict) -> bool:
    token = (getattr(websocket, "headers", {}) or {}).get("authorization", "")
    user = await verify_token(token)
    if user is None:
        return False
    metadata["user_id"] = user.id   # mutate metadata to attach identity
    return True


m = ConnectionManager(on_connect=authenticate)

Authorize rooms

room_validator is enforced for both join() and the initial rooms=[...] passed to connect(). A denial raises PermissionError, so an unauthenticated client can never enter a room it isn't allowed into.

DoS limits

• max_connections defaults to 10_000. Set it to None only if you have your own admission control — None means unbounded and is an A05 DoS risk.

• max_message_bytes defaults to 1_048_576 (1 MiB). It is advisory: your receive loop must enforce it. The receive_text(conn) / receive_json(conn) helpers wrap the underlying receive, reject oversized frames (closing with code 1009), and drop the connection:

  conn = await m.connect(websocket)
  while True:
      msg = await m.receive_text(conn)   # raises ValueError if over the limit
      ...
  

Tenant isolation

• require_room=True makes room-less broadcast_text/broadcast_json raise ValueError, preventing accidental cross-tenant fan-out.
• The Redis backplane drops room-less messages by default (they would otherwise broadcast to every connection). Set bind_manager(bp, m, allow_global=True) — or init_websockets(app, allow_global_broadcast=True) — only if you really want server-wide broadcasts.

Logging

Security-relevant events are logged on the hawkapi_websockets logger: info on connect/disconnect, warning on Origin rejection, on_connect/room_validator denial, oversized messages, dropped room-less backplane messages, and when max_connections is hit.

Broadcasting

await m.broadcast_text("hi")                              # everyone
await m.broadcast_json({"event": "x"}, room="lobby")      # one room
await m.broadcast_text("hi", exclude=[conn.id])           # skip the sender
await m.send_to(connection_id, {"private": True})         # direct

Failed sends auto-drop the broken connection, so a misbehaving client never blocks the broadcast.

Redis backplane

When you run multiple worker processes, broadcasts must travel across them. Plug in the Redis backplane and every publish() is fanned out to every replica's ConnectionManager.

from hawkapi_websockets import RedisBackplane, init_websockets

backplane = RedisBackplane(url="redis://localhost:6379/0", channel="hawkapi:ws")
m = init_websockets(app, backplane=backplane)


# Anywhere in your code:
await backplane.publish({"kind": "json", "room": "lobby", "payload": {"event": "tick"}})

The backplane subscribes during app.on_startup and shuts down with the app.

Heartbeat

from hawkapi_websockets import HeartbeatConfig, HeartbeatMonitor

monitor = HeartbeatMonitor(manager=m, config=HeartbeatConfig(interval_seconds=30, timeout_seconds=90))
monitor.start()             # background task pings every interval, drops stale connections


@app.websocket("/ws")
async def ws(websocket):
    await websocket.accept()
    conn = await m.connect(websocket)
    monitor.touch(conn.id)
    try:
        async for msg in websocket.iter_text():
            monitor.touch(conn.id)        # client liveness signal
            ...
    finally:
        await m.disconnect(conn.id)

Testing

The manager works with any object implementing WebSocketLike (send_text/send_bytes/close), so you can test broadcast logic without a real WebSocket connection.

class FakeWS:
    def __init__(self): self.sent: list[str] = []
    async def send_text(self, data): self.sent.append(data)
    async def send_bytes(self, data): ...
    async def close(self, code=1000): ...


async def test_chat_broadcast():
    m = ConnectionManager()
    a, b = FakeWS(), FakeWS()
    await m.connect(a, connection_id="alice", rooms=["lobby"])
    await m.connect(b, connection_id="bob", rooms=["lobby"])
    await m.broadcast_text("hi", room="lobby", exclude=["alice"])
    assert b.sent == ["hi"]

Development

git clone https://github.com/Hawk-API/hawkapi-websockets.git
cd hawkapi-websockets
uv sync --extra dev
uv run pytest -q
uv run ruff check . && uv run ruff format --check .
uv run pyright src/

License

MIT.