fix: use utcnow() for refresh calculation (#155)

Author: jackwotherspoon

google/cloud/alloydb/connector/refresh.py

@@ -35,15 +35,17 @@
 _refresh_buffer: int = 4 * 60  # 4 minutes
 
 
-def _seconds_until_refresh(expiration: datetime, now: datetime = datetime.now()) -> int:
+def _seconds_until_refresh(
+    expiration: datetime, now: datetime = datetime.utcnow()
+) -> int:
     """
     Calculates the duration to wait before starting the next refresh.
     Usually the duration will be half of the time until certificate
     expiration.
 
     Args:
         expiration (datetime.datetime): Time of certificate expiration.
-        now (datetime.datetime): Current time. Defaults to datetime.now()
+        now (datetime.datetime): Current time. Defaults to datetime.utcnow()
     Returns:
         int: Time in seconds to wait before performing next refresh.
     """
@@ -107,7 +109,7 @@ async def _is_valid(task: asyncio.Task) -> bool:
     try:
         result = await task
         # valid if current time is before cert expiration
-        if datetime.now() < result.expiration:
+        if datetime.utcnow() < result.expiration:
             return True
     except Exception:
         # suppress any errors from task

tests/unit/mocks.py

@@ -29,7 +29,7 @@ def __init__(self) -> None:
     def refresh(self, request: Callable) -> None:
         """Refreshes the access token."""
         self.token = "12345"
-        self.expiry = datetime.now() + timedelta(minutes=60)
+        self.expiry = datetime.utcnow() + timedelta(minutes=60)
 
     @property
     def expired(self) -> bool:
@@ -67,7 +67,7 @@ def generate_cert(
     # generate private key
     key = rsa.generate_private_key(public_exponent=65537, key_size=2048)
     # calculate expiry time
-    now = datetime.now()
+    now = datetime.utcnow()
     expiration = now + timedelta(minutes=expires_in)
     # configure cert subject
     subject = issuer = x509.Name(
@@ -103,8 +103,8 @@ def __init__(
         name: str = "test-instance",
         ip_address: str = "127.0.0.1",
         server_name: str = "00000000-0000-0000-0000-000000000000.server.alloydb",
-        cert_before: datetime = datetime.now(),
-        cert_expiry: datetime = datetime.now() + timedelta(hours=1),
+        cert_before: datetime = datetime.utcnow(),
+        cert_expiry: datetime = datetime.utcnow() + timedelta(hours=1),
     ) -> None:
         self.project = project
         self.region = region