[sqlserver] fix bug where tempdb is wrongly excluded in database files metrics (#19803)

* fix bug where tempdb is wronly excluded

* add changelog

Author: lu-zhengda

sqlserver/changelog.d/19803.fixed

@@ -0,0 +1 @@
+Fix a bug where `tempdb` is wrongly excluded from database files metrics due to all instances inherited from `SqlserverDatabaseMetricsBase` share the same reference of auto-discovered databases.

sqlserver/datadog_checks/sqlserver/database_metrics/base.py

@@ -3,6 +3,7 @@
 # Licensed under a 3-clause BSD style license (see LICENSE)
 
 
+import copy
 from typing import Callable, List, Optional
 
 from datadog_checks.base.log import get_check_logger
@@ -28,7 +29,7 @@ def __init__(
         ] = new_query_executor
         self.execute_query_handler: Callable[[str, Optional[str]], List[tuple]] = execute_query_handler
         self.track_operation_time: bool = track_operation_time
-        self._databases: Optional[List[str]] = databases
+        self._databases: Optional[List[str]] = copy.copy(databases)
         self._query_executors: List[QueryExecutor] = []
         self.log = get_check_logger()
 

sqlserver/tests/test_database_metrics.py

@@ -34,6 +34,7 @@
     SqlserverServerStateMetrics,
     SqlserverTempDBFileSpaceUsageMetrics,
 )
+from datadog_checks.sqlserver.utils import Database
 
 from .common import (
     CHECK_NAME,
@@ -1491,3 +1492,35 @@ def test_sqlserver_database_metrics_defaults(
             databases=AUTODISCOVERY_DBS,
         )
         assert database_metrics.enabled == enabled
+
+
+@pytest.mark.unit
+def test_sqlserver_database_metrics_init(
+    init_config,
+    instance_docker_metrics,
+):
+    instance_docker_metrics['database_autodiscovery'] = True
+    instance_docker_metrics['database_metrics'] = {
+        'index_usage_metrics': {
+            'enabled': True,
+            'enabled_tempdb': False,
+        },
+    }
+
+    sqlserver_check = SQLServer(CHECK_NAME, init_config, [instance_docker_metrics])
+    sqlserver_check.databases = {Database(db) for db in AUTODISCOVERY_DBS + ['tempdb']}
+    assert sqlserver_check.database_metrics is not None
+
+    index_usage_metrics = [
+        metric for metric in sqlserver_check.database_metrics if isinstance(metric, SqlserverIndexUsageMetrics)
+    ]
+    assert len(index_usage_metrics) == 1
+    assert index_usage_metrics[0].enabled is True
+    assert 'tempdb' not in index_usage_metrics[0].databases
+
+    database_file_metrics = [
+        metric for metric in sqlserver_check.database_metrics if isinstance(metric, SqlserverDatabaseFilesMetrics)
+    ]
+    assert len(database_file_metrics) == 1
+    assert database_file_metrics[0].enabled is True
+    assert 'tempdb' in database_file_metrics[0].databases