fix: Use utcnow() in refresh calculation (#890)

Author: enkelli

google/cloud/sql/connector/refresh_utils.py

@@ -220,7 +220,7 @@ def _seconds_until_refresh(
     :returns: Time in seconds to wait before performing next refresh.
     """
 
-    duration = int((expiration - datetime.datetime.now()).total_seconds())
+    duration = int((expiration - datetime.datetime.utcnow()).total_seconds())
 
     # if certificate duration is less than 1 hour
     if duration < 3600:
@@ -237,7 +237,7 @@ async def _is_valid(task: asyncio.Task) -> bool:
     try:
         metadata = await task
         # only valid if now is before the cert expires
-        if datetime.datetime.now() < metadata.expiration:
+        if datetime.datetime.utcnow() < metadata.expiration:
             return True
     except Exception:
         # supress any errors from task

tests/unit/mocks.py

@@ -66,11 +66,11 @@ def __init__(
 
 
 async def instance_metadata_success(*args: Any, **kwargs: Any) -> MockMetadata:
-    return MockMetadata(datetime.datetime.now() + datetime.timedelta(minutes=10))
+    return MockMetadata(datetime.datetime.utcnow() + datetime.timedelta(minutes=10))
 
 
 async def instance_metadata_expired(*args: Any, **kwargs: Any) -> MockMetadata:
-    return MockMetadata(datetime.datetime.now() - datetime.timedelta(minutes=10))
+    return MockMetadata(datetime.datetime.utcnow() - datetime.timedelta(minutes=10))
 
 
 async def instance_metadata_error(*args: Any, **kwargs: Any) -> None:

tests/unit/test_refresh_utils.py

@@ -326,7 +326,9 @@ def test_seconds_until_refresh_over_1_hour() -> None:
     """
     # using pytest.approx since sometimes can be off by a second
     assert (
-        pytest.approx(_seconds_until_refresh(datetime.now() + timedelta(minutes=62)), 1)
+        pytest.approx(
+            _seconds_until_refresh(datetime.utcnow() + timedelta(minutes=62)), 1
+        )
         == 31 * 60
     )
 
@@ -340,7 +342,9 @@ def test_seconds_until_refresh_under_1_hour_over_4_mins() -> None:
     """
     # using pytest.approx since sometimes can be off by a second
     assert (
-        pytest.approx(_seconds_until_refresh(datetime.now() + timedelta(minutes=5)), 1)
+        pytest.approx(
+            _seconds_until_refresh(datetime.utcnow() + timedelta(minutes=5)), 1
+        )
         == 60
     )
 
@@ -351,4 +355,4 @@ def test_seconds_until_refresh_under_4_mins() -> None:
 
     If expiration is under 4 minutes, should return 0.
     """
-    assert _seconds_until_refresh(datetime.now() + timedelta(minutes=3)) == 0
+    assert _seconds_until_refresh(datetime.utcnow() + timedelta(minutes=3)) == 0