Zeroconf Async Migration

Zeroconf Async Migration

Fix common issues when using python-zeroconf for mDNS service discovery.

Async API (zeroconf >= 0.131)

WRONG (sync, deprecated):

info = zeroconf.get_service_info(service_type, name, timeout=3000)

Error: Use AsyncServiceInfo.async_request from the event loop

RIGHT (async):

info = await zeroconf.async_get_service_info(service_type, name)

Thread Safety

ServiceBrowser fires callbacks from its own internal thread. Store the loop:

# Store it:
def set_event_loop(self, loop):
    self._loop = loop

# Callback (zeroconf thread):
def on_change(self, zc, st, name, sc):
    if hasattr(self, '_loop') and self._loop:
        asyncio.run_coroutine_threadsafe(
            self._handle(zc, st, name), self._loop)

# Handler (async thread):
async def _handle(self, zc, st, name):
    info = await zc.async_get_service_info(st, name)

Registration Conflicts

try:
    zeroconf.register_service(info)
except Exception as e:
    if "already" in str(e).lower():
        info.name = f"{self._name}-{suffix}.{SERVICE_TYPE}"
        zeroconf.register_service(info)

Properties Are Bytes

# Reading properties:
device_id = info.properties.get(b"device_id", b"").decode()

Cleanup

def stop(self):
    if self._zeroconf:
        try: self._zeroconf.unregister_service(self._service_info)
        except: pass
        self._zeroconf.close()