Ensure SSL certificate loading is done in a non-blocking fashion

pyproject.toml

@@ -15,7 +15,7 @@ name = "kingspan-connect-sensor"
 packages = [{include = "connectsensor", from = "src"}]
 readme = "README.md"
 repository = "https://github.com/masaccio/kingspan-connect-sensor"
-version = "3.0.4"
+version = "3.0.5"
 
 [tool.poetry.dependencies]
 async-property = "^0.2.1"

src/connectsensor/client.py

@@ -4,6 +4,7 @@
 from zeep import Client as SoapClient
 from zeep import AsyncClient as AsyncSoapClient
 
+from asyncio import get_running_loop
 from .tank import Tank, AsyncTank
 from .exceptions import APIError
 
@@ -70,17 +71,28 @@ def _get_history(self, signalman_no, start_date=None, end_date=None):
 
 class AsyncSensorClient:
     def __init__(self, base=DEFAULT_SERVER):
-        url = urljoin(base, WSDL_PATH)
-        self._soap_client = AsyncSoapClient(url)
-        self._soap_client.set_ns_prefix(None, "http://mobileapp/")
+        self._soap_url = urljoin(base, WSDL_PATH)
+        self._soap_client = None
 
     async def __aenter__(self):
         return self
 
     async def __aexit__(self, exc_t, exc_v, exc_tb):
         pass
 
+    async def _init_zeep(self):
+        # Zeep.AsyncClient uses httpx which loads SSL cerficates at construction
+        # time. An alternative would be disabling certificate verification.
+        loop = get_running_loop()
+        self._soap_client = await loop.run_in_executor(
+            None, AsyncSoapClient, self._soap_url
+        )
+        self._soap_client.set_ns_prefix(None, "http://mobileapp/")
+
     async def login(self, username, password):
+        if self._soap_client is None:
+            await self._init_zeep()
+
         self._username = username
         self._password = password