Enable logging of SQL statements

docs/deployment/@relengapi/config.rst

@@ -28,6 +28,10 @@ This is effective for development, but certainly not for production.
 The database for the relengapi core is named ``relengapi``.
 Other blueprints may require additional URIs.
 
+If you ever need to see what SQLAlchemy is doing with the connection pool, it is useful to enable verbose query logging.
+To do so, set ``SQLALCHEMY_DB_LOG = True``.
+Note that this output is *very* verbose and may severely impact site performance.
+
 .. _Deployment-Authentication:
 
 Authentication
@@ -130,19 +134,19 @@ The configuration looks like this::
 
         # Base LDAP URI
         'uri': "ldaps://your.ldap.server/",
-    
+
         # This needs to be a user that has sufficient rights to read users and groups
         'login_dn': "<dn for bind user>",
         'login_password': "<password for bind user>",
-    
+
         # The search bases for users and groups, respectively
         'user_base': 'o=users,dc=example,dc=com',
         'group_base': 'o=groups,dc=example,dc=com',
-    
+
         # set this to True for extra logging
         'debug': False,
     }
- 
+
 Permissions are cumulative: a person has a permission if they are a member of any group configured with that permission.
 In the example above, a user in both ``team_relops`` and ``team_releng`` would have permission to create tasks and to issue and view tokens.
 The group name ``<everyone>`` is treated specially: it grants permission to all authenticated users, regardless of authentication mechanism.

relengapi/lib/db.py

@@ -20,6 +20,7 @@
 from sqlalchemy.orm import scoping
 from sqlalchemy.pool import Pool
 
+
 logger = logging.getLogger(__name__)
 
 
@@ -81,6 +82,13 @@ def _get_db_config(self, dbname):
 
     @synchronized(threading.Lock())
     def engine(self, dbname):
+        # Set the log level for db logs
+        sqla_logger = logging.getLogger('sqlalchemy.engine')
+        if self.app.config.get('SQLALCHEMY_DB_LOG', False):
+            sqla_logger.setLevel(logging.INFO)
+        else:
+            sqla_logger.setLevel(logging.WARNING)
+
         if dbname not in self._engines:
             uri = self._get_db_config(dbname)
             self._engines[dbname] = engine = sa.create_engine(uri)

settings_example.py

@@ -15,6 +15,9 @@
 # configuration is present, is to use '*.db' files in the directory containing
 # the RelengAPI source code.
 
+# set to True to log SQLAlchemy engine activities (very verbose!)
+# SQLALCHEMY_DB_LOG = False
+
 # ===== Authentication and Authorization =====
 
 RELENGAPI_AUTHENTICATION = {