Added lag_aware_tolerance parameter to LagAwareHealthcheck (#3752)

Author: vladvildanov

redis/multidb/healthcheck.py

@@ -86,6 +86,7 @@ def __init__(
         self,
         retry: Retry = Retry(retries=DEFAULT_HEALTH_CHECK_RETRIES, backoff=DEFAULT_HEALTH_CHECK_BACKOFF),
         rest_api_port: int = 9443,
+        lag_aware_tolerance: int = 100,
         timeout: float = DEFAULT_TIMEOUT,
         auth_basic: Optional[Tuple[str, str]] = None,
         verify_tls: bool = True,
@@ -104,6 +105,7 @@ def __init__(
         Args:
             retry: Retry configuration for health checks
             rest_api_port: Port number for Redis Enterprise REST API (default: 9443)
+            lag_aware_tolerance: Tolerance in lag between databases in MS (default: 100)
             timeout: Request timeout in seconds (default: DEFAULT_TIMEOUT)
             auth_basic: Tuple of (username, password) for basic authentication
             verify_tls: Whether to verify TLS certificates (default: True)
@@ -130,6 +132,7 @@ def __init__(
             client_key_password=client_key_password
         )
         self._rest_api_port = rest_api_port
+        self._lag_aware_tolerance = lag_aware_tolerance
 
     def check_health(self, database) -> bool:
         if database.health_check_url is None:
@@ -163,7 +166,8 @@ def check_health(self, database) -> bool:
             logger.warning("LagAwareHealthCheck failed: Couldn't find a matching bdb")
             raise ValueError("Could not find a matching bdb")
 
-        url = f"/v1/local/bdbs/{matching_bdb['uid']}/endpoint/availability"
+        url = (f"/v1/local/bdbs/{matching_bdb['uid']}/endpoint/availability"
+               f"?extend_check=lag&availability_lag_tolerance_ms={self._lag_aware_tolerance}")
         self._http_client.get(url, expect_json=False)
 
         # Status checked in an http client, otherwise HttpError will be raised

tests/test_multidb/test_healthcheck.py

@@ -4,7 +4,6 @@
 
 from redis.backoff import ExponentialBackoff
 from redis.multidb.database import Database
-from redis.multidb.healthcheck import EchoHealthCheck
 from redis.http.http_client import HttpError
 from redis.multidb.healthcheck import EchoHealthCheck, LagAwareHealthCheck
 from redis.multidb.circuit import State as CBState
@@ -74,7 +73,7 @@ def test_database_is_healthy_when_bdb_matches_by_dns_name(self, mock_client, moc
 
         hc = LagAwareHealthCheck(
             retry=Retry(backoff=ExponentialBackoff(cap=1.0), retries=3),
-            rest_api_port=1234,
+            rest_api_port=1234, lag_aware_tolerance=150
         )
         # Inject our mocked http client
         hc._http_client = mock_http
@@ -89,7 +88,7 @@ def test_database_is_healthy_when_bdb_matches_by_dns_name(self, mock_client, moc
         first_call = mock_http.get.call_args_list[0]
         second_call = mock_http.get.call_args_list[1]
         assert first_call.args[0] == "/v1/bdbs"
-        assert second_call.args[0] == "/v1/local/bdbs/bdb-1/endpoint/availability"
+        assert second_call.args[0] == "/v1/local/bdbs/bdb-1/endpoint/availability?extend_check=lag&availability_lag_tolerance_ms=150"
         assert second_call.kwargs.get("expect_json") is False
 
     def test_database_is_healthy_when_bdb_matches_by_addr(self, mock_client, mock_cb):
@@ -121,7 +120,7 @@ def test_database_is_healthy_when_bdb_matches_by_addr(self, mock_client, mock_cb
 
         assert hc.check_health(db) is True
         assert mock_http.get.call_count == 2
-        assert mock_http.get.call_args_list[1].args[0] == "/v1/local/bdbs/bdb-42/endpoint/availability"
+        assert mock_http.get.call_args_list[1].args[0] == "/v1/local/bdbs/bdb-42/endpoint/availability?extend_check=lag&availability_lag_tolerance_ms=100"
 
     def test_raises_value_error_when_no_matching_bdb(self, mock_client, mock_cb):
         """