flask-security with SQLALCHEMY_BINDS loses connections from pool for static files - flask-login

Question

flask-security with SQLALCHEMY_BINDS loses connections from pool for static files -- at least I think what is happening.
First comment under Caching Flask-Login user_loader suggests using flask-principal's skip_static=True, but I don't see that that flask-principal parameter is accessible when using flask-security.
Using
Flask-Login==0.5.0
Flask-Mail==0.9.1
flask-nav==0.6
Flask-Principal==0.4.0
Flask-Security-Too==3.3.3
Flask-SQLAlchemy==2.4.1
Flask-WTF==0.14.3
SQLAlchemy==1.3.13
I initialize the SQLALCHEMY variables as below
class RealDb(Config):
def __init__(self, configfiles):
if type(configfiles) == str:
configfiles = [configfiles]
# connect to database based on configuration
config = {}
for configfile in configfiles:
config.update(getitems(configfile, 'database'))
dbuser = config['dbuser']
password = config['dbpassword']
dbserver = config['dbserver']
dbname = config['dbname']
# app.logger.debug('using mysql://{uname}:*******#{server}/{dbname}'.format(uname=dbuser,server=dbserver,dbname=dbname))
db_uri = 'mysql://{uname}:{pw}#{server}/{dbname}'.format(uname=dbuser, pw=password, server=dbserver,
dbname=dbname)
self.SQLALCHEMY_DATABASE_URI = db_uri
# https://flask-sqlalchemy.palletsprojects.com/en/2.x/binds/
userdbuser = config['userdbuser']
userpassword = config['userdbpassword']
userdbserver = config['userdbserver']
userdbname = config['userdbname']
userdb_uri = 'mysql://{uname}:{pw}#{server}/{dbname}'.format(uname=userdbuser, pw=userpassword, server=userdbserver,
dbname=userdbname)
self.SQLALCHEMY_BINDS = {
'users': userdb_uri
}
My users model (the main model is empty at this point)
# pypi
from flask_sqlalchemy import SQLAlchemy
from flask_security import UserMixin, RoleMixin
# set up database - SQLAlchemy() must be done after app.config SQLALCHEMY_* assignments
db = SQLAlchemy()
Table = db.Table
Column = db.Column
Integer = db.Integer
Float = db.Float
Boolean = db.Boolean
String = db.String
Text = db.Text
Date = db.Date
Time = db.Time
DateTime = db.DateTime
Sequence = db.Sequence
Enum = db.Enum
UniqueConstraint = db.UniqueConstraint
ForeignKey = db.ForeignKey
relationship = db.relationship
backref = db.backref
object_mapper = db.object_mapper
Base = db.Model
# some string sizes
DESCR_LEN = 512
INTEREST_LEN = 32
APPLICATION_LEN = 32
# role management, some of these are overloaded
USERROLEDESCR_LEN = 512
ROLENAME_LEN = 32
EMAIL_LEN = 100
NAME_LEN = 256
PASSWORD_LEN = 255
UNIQUIFIER_LEN = 255
# common roles
ROLE_SUPER_ADMIN = 'super-admin'
userinterest_table = Table('users_interests', Base.metadata,
Column('user_id', Integer, ForeignKey('user.id')),
Column('interest_id', Integer, ForeignKey('interest.id')),
info={'bind_key': 'users'},
)
appinterest_table = Table('apps_interests', Base.metadata,
Column('application_id', Integer, ForeignKey('application.id')),
Column('interest_id', Integer, ForeignKey('interest.id')),
info={'bind_key': 'users'},
)
class Interest(Base):
__tablename__ = 'interest'
__bind_key__ = 'users'
id = Column(Integer(), primary_key=True)
version_id = Column(Integer, nullable=False, default=1)
interest = Column(String(INTEREST_LEN))
users = relationship("User",
secondary=userinterest_table,
backref=backref("interests"))
applications = relationship("Application",
secondary=appinterest_table,
backref=backref("interests"))
description = Column(String(DESCR_LEN))
public = Column(Boolean)
class Application(Base):
__tablename__ = 'application'
__bind_key__ = 'users'
id = Column(Integer(), primary_key=True)
application = Column(String(APPLICATION_LEN))
# user role management
# adapted from
# https://flask-security-too.readthedocs.io/en/stable/quickstart.html (SQLAlchemy Application)
class RolesUsers(Base):
__tablename__ = 'roles_users'
__bind_key__ = 'users'
id = Column(Integer(), primary_key=True)
user_id = Column('user_id', Integer(), ForeignKey('user.id'))
role_id = Column('role_id', Integer(), ForeignKey('role.id'))
class Role(Base, RoleMixin):
__tablename__ = 'role'
__bind_key__ = 'users'
id = Column(Integer(), primary_key=True)
version_id = Column(Integer, nullable=False, default=1)
name = Column(String(ROLENAME_LEN), unique=True)
description = Column(String(USERROLEDESCR_LEN))
class User(Base, UserMixin):
__tablename__ = 'user'
__bind_key__ = 'users'
id = Column(Integer, primary_key=True)
version_id = Column(Integer, nullable=False, default=1)
email = Column( String(EMAIL_LEN), unique=True ) # = username
password = Column( String(PASSWORD_LEN) )
name = Column( String(NAME_LEN) )
given_name = Column( String(NAME_LEN) )
last_login_at = Column( DateTime() )
current_login_at = Column( DateTime() )
last_login_ip = Column( String(100) )
current_login_ip = Column( String(100) )
login_count = Column( Integer )
active = Column( Boolean() )
fs_uniquifier = Column( String(UNIQUIFIER_LEN) )
confirmed_at = Column( DateTime() )
roles = relationship('Role', secondary='roles_users',
backref=backref('users', lazy='dynamic'))
Logging connection pool:
logging.basicConfig()
logging.getLogger('sqlalchemy.pool').setLevel(logging.DEBUG)
Using the above I see connections not released for static files which eventually causes sqlalchemy.exc.TimeoutError: QueuePool limit of size 10 overflow 10 reached, connection timed out, timeout 30 (Background on this error at: http://sqlalche.me/e/3o7r). (I believe the db.session.commit() within /admin/users causes that connection to be returned).
DEBUG:sqlalchemy.pool.impl.QueuePool:Created new connection <_mysql.connection open to '127.0.0.1' at 0000020389174368>
DEBUG:sqlalchemy.pool.impl.QueuePool:Connection <_mysql.connection open to '127.0.0.1' at 0000020389174368> checked out from pool
127.0.0.1 - - [10/Mar/2020 15:10:03] "GET /static/js/jquery-ui-1.12.1.custom/images/ui-bg_glass_50_3baae3_1x400.png HTTP/1.1" 200 -
INFO:werkzeug:127.0.0.1 - - [10/Mar/2020 15:10:03] "GET /static/js/jquery-ui-1.12.1.custom/images/ui-bg_glass_50_3baae3_1x400.png HTTP/1.1" 200 -
DEBUG:sqlalchemy.pool.impl.QueuePool:Created new connection <_mysql.connection open to '127.0.0.1' at 00000203891761C8>
DEBUG:sqlalchemy.pool.impl.QueuePool:Connection <_mysql.connection open to '127.0.0.1' at 00000203891761C8> checked out from pool
request.path = /admin/users
DEBUG:sqlalchemy.pool.impl.QueuePool:Connection <_mysql.connection open to '127.0.0.1' at 00000203891761C8> being returned to pool
DEBUG:sqlalchemy.pool.impl.QueuePool:Connection <_mysql.connection open to '127.0.0.1' at 00000203891761C8> rollback-on-return
DEBUG:sqlalchemy.pool.impl.QueuePool:Connection <_mysql.connection open to '127.0.0.1' at 00000203891761C8> checked out from pool
[2020-03-10 15:10:05,773] DEBUG in tables: rendertemplate(): self.templateargs = {}
DEBUG:members:rendertemplate(): self.templateargs = {}
127.0.0.1 - - [10/Mar/2020 15:10:05] "GET /admin/users HTTP/1.1" 200 -
INFO:werkzeug:127.0.0.1 - - [10/Mar/2020 15:10:05] "GET /admin/users HTTP/1.1" 200 -
DEBUG:sqlalchemy.pool.impl.QueuePool:Created new connection <_mysql.connection open to '127.0.0.1' at 0000020389175298>
DEBUG:sqlalchemy.pool.impl.QueuePool:Connection <_mysql.connection open to '127.0.0.1' at 0000020389175298> checked out from pool
127.0.0.1 - - [10/Mar/2020 15:10:06] "GET /static/js/jquery-ui-1.12.1.custom/jquery-ui.css HTTP/1.1" 200 -
INFO:werkzeug:127.0.0.1 - - [10/Mar/2020 15:10:06] "GET /static/js/jquery-ui-1.12.1.custom/jquery-ui.css HTTP/1.1" 200 -
DEBUG:sqlalchemy.pool.impl.QueuePool:Created new connection <_mysql.connection open to '127.0.0.1' at 00000203891770F8>
:
Traceback (most recent call last):
File "C:\Users\lking\Documents\Lou's Software\projects\members\members\venv\lib\site-packages\flask\app.py", line 2463, in __call__
return self.wsgi_app(environ, start_response)
File "C:\Users\lking\Documents\Lou's Software\projects\members\members\venv\lib\site-packages\flask\app.py", line 2449, in wsgi_app
response = self.handle_exception(e)
File "C:\Users\lking\Documents\Lou's Software\projects\members\members\venv\lib\site-packages\flask\app.py", line 1866, in handle_exception
reraise(exc_type, exc_value, tb)
File "C:\Users\lking\Documents\Lou's Software\projects\members\members\venv\lib\site-packages\flask\_compat.py", line 39, in reraise
raise value
File "C:\Users\lking\Documents\Lou's Software\projects\members\members\venv\lib\site-packages\flask\app.py", line 2446, in wsgi_app
response = self.full_dispatch_request()
File "C:\Users\lking\Documents\Lou's Software\projects\members\members\venv\lib\site-packages\flask\app.py", line 1951, in full_dispatch_request
rv = self.handle_user_exception(e)
File "C:\Users\lking\Documents\Lou's Software\projects\members\members\venv\lib\site-packages\flask\app.py", line 1820, in handle_user_exception
reraise(exc_type, exc_value, tb)
File "C:\Users\lking\Documents\Lou's Software\projects\members\members\venv\lib\site-packages\flask\_compat.py", line 39, in reraise
raise value
File "C:\Users\lking\Documents\Lou's Software\projects\members\members\venv\lib\site-packages\flask\app.py", line 1947, in full_dispatch_request
rv = self.preprocess_request()
File "C:\Users\lking\Documents\Lou's Software\projects\members\members\venv\lib\site-packages\flask\app.py", line 2241, in preprocess_request
rv = func()
File "C:\Users\lking\Documents\Lou's Software\projects\members\members\venv\lib\site-packages\flask_principal.py", line 477, in _on_before_request
identity = loader()
File "C:\Users\lking\Documents\Lou's Software\projects\members\members\venv\lib\site-packages\flask_security\core.py", line 405, in _identity_loader
if not isinstance(current_user._get_current_object(), AnonymousUserMixin):
File "C:\Users\lking\Documents\Lou's Software\projects\members\members\venv\lib\site-packages\werkzeug\local.py", line 306, in _get_current_object
return self.__local()
File "C:\Users\lking\Documents\Lou's Software\projects\members\members\venv\lib\site-packages\flask_login\utils.py", line 26, in <lambda>
current_user = LocalProxy(lambda: _get_user())
File "C:\Users\lking\Documents\Lou's Software\projects\members\members\venv\lib\site-packages\flask_login\utils.py", line 346, in _get_user
current_app.login_manager._load_user()
File "C:\Users\lking\Documents\Lou's Software\projects\members\members\venv\lib\site-packages\flask_login\login_manager.py", line 318, in _load_user
user = self._user_callback(user_id)
File "C:\Users\lking\Documents\Lou's Software\projects\members\members\venv\lib\site-packages\flask_security\core.py", line 345, in _user_loader
user = _security.datastore.find_user(id=user_id)
File "C:\Users\lking\Documents\Lou's Software\projects\members\members\venv\lib\site-packages\flask_security\datastore.py", line 382, in find_user
return query.filter_by(**kwargs).first()
File "C:\Users\lking\Documents\Lou's Software\projects\members\members\venv\lib\site-packages\sqlalchemy\orm\query.py", line 3287, in first
ret = list(self[0:1])
File "C:\Users\lking\Documents\Lou's Software\projects\members\members\venv\lib\site-packages\sqlalchemy\orm\query.py", line 3065, in __getitem__
return list(res)
File "C:\Users\lking\Documents\Lou's Software\projects\members\members\venv\lib\site-packages\sqlalchemy\orm\query.py", line 3389, in __iter__
return self._execute_and_instances(context)
File "C:\Users\lking\Documents\Lou's Software\projects\members\members\venv\lib\site-packages\sqlalchemy\orm\query.py", line 3411, in _execute_and_instances
querycontext, self._connection_from_session, close_with_result=True
File "C:\Users\lking\Documents\Lou's Software\projects\members\members\venv\lib\site-packages\sqlalchemy\orm\query.py", line 3426, in _get_bind_args
mapper=self._bind_mapper(), clause=querycontext.statement, **kw
File "C:\Users\lking\Documents\Lou's Software\projects\members\members\venv\lib\site-packages\sqlalchemy\orm\query.py", line 3404, in _connection_from_session
conn = self.session.connection(**kw)
File "C:\Users\lking\Documents\Lou's Software\projects\members\members\venv\lib\site-packages\sqlalchemy\orm\session.py", line 1133, in connection
execution_options=execution_options,
File "C:\Users\lking\Documents\Lou's Software\projects\members\members\venv\lib\site-packages\sqlalchemy\orm\session.py", line 1139, in _connection_for_bind
engine, execution_options
File "C:\Users\lking\Documents\Lou's Software\projects\members\members\venv\lib\site-packages\sqlalchemy\orm\session.py", line 432, in _connection_for_bind
conn = bind._contextual_connect()
File "C:\Users\lking\Documents\Lou's Software\projects\members\members\venv\lib\site-packages\sqlalchemy\engine\base.py", line 2242, in _contextual_connect
self._wrap_pool_connect(self.pool.connect, None),
File "C:\Users\lking\Documents\Lou's Software\projects\members\members\venv\lib\site-packages\sqlalchemy\engine\base.py", line 2276, in _wrap_pool_connect
return fn()
File "C:\Users\lking\Documents\Lou's Software\projects\members\members\venv\lib\site-packages\sqlalchemy\pool\base.py", line 363, in connect
return _ConnectionFairy._checkout(self)
File "C:\Users\lking\Documents\Lou's Software\projects\members\members\venv\lib\site-packages\sqlalchemy\pool\base.py", line 773, in _checkout
fairy = _ConnectionRecord.checkout(pool)
File "C:\Users\lking\Documents\Lou's Software\projects\members\members\venv\lib\site-packages\sqlalchemy\pool\base.py", line 492, in checkout
rec = pool._do_get()
File "C:\Users\lking\Documents\Lou's Software\projects\members\members\venv\lib\site-packages\sqlalchemy\pool\impl.py", line 131, in _do_get
code="3o7r",
sqlalchemy.exc.TimeoutError: QueuePool limit of size 10 overflow 10 reached, connection timed out, timeout 30 (Background on this error at: http://sqlalche.me/e/3o7r)
If I don't use the SQLALCHEMY_BINDS the connections are released to the pool, similar to below:
DEBUG:sqlalchemy.pool.impl.QueuePool:Created new connection <_mysql.connection open to '127.0.0.1' at 000002A68ED917D8>
DEBUG:sqlalchemy.pool.impl.QueuePool:Created new connection <_mysql.connection open to '127.0.0.1' at 000002A68ED94F88>
DEBUG:sqlalchemy.pool.impl.QueuePool:Connection <_mysql.connection open to '127.0.0.1' at 000002A68ED917D8> checked out from pool
DEBUG:sqlalchemy.pool.impl.QueuePool:Connection <_mysql.connection open to '127.0.0.1' at 000002A68ED94F88> checked out from pool
request.path = /admin/users
DEBUG:sqlalchemy.pool.impl.QueuePool:Connection <_mysql.connection open to '127.0.0.1' at 000002A68ED917D8> being returned to pool
DEBUG:sqlalchemy.pool.impl.QueuePool:Connection <_mysql.connection open to '127.0.0.1' at 000002A68ED917D8> rollback-on-return, via agent
127.0.0.1 - - [10/Mar/2020 15:25:44] "GET /static/js/jquery-ui-1.12.1.custom/images/ui-icons_ffffff_256x240.png HTTP/1.1" 200 -
INFO:werkzeug:127.0.0.1 - - [10/Mar/2020 15:25:44] "GET /static/js/jquery-ui-1.12.1.custom/images/ui-icons_ffffff_256x240.png HTTP/1.1" 200 -
DEBUG:sqlalchemy.pool.impl.QueuePool:Connection <_mysql.connection open to '127.0.0.1' at 000002A68ED94F88> being returned to pool
DEBUG:sqlalchemy.pool.impl.QueuePool:Connection <_mysql.connection open to '127.0.0.1' at 000002A68ED94F88> rollback-on-return
DEBUG:sqlalchemy.pool.impl.QueuePool:Connection <_mysql.connection open to '127.0.0.1' at 000002A68ED917D8> checked out from pool
[2020-03-10 15:25:44,829] DEBUG in tables: rendertemplate(): self.templateargs = {}
DEBUG:runningroutes:rendertemplate(): self.templateargs = {}
DEBUG:sqlalchemy.pool.impl.QueuePool:Connection <_mysql.connection open to '127.0.0.1' at 000002A68ED917D8> being returned to pool
DEBUG:sqlalchemy.pool.impl.QueuePool:Connection <_mysql.connection open to '127.0.0.1' at 000002A68ED917D8> rollback-on-return, via agent
:

Answer 1

Issue was that I was using two different SQLAlchemy() instances. Not sure how I could have been looking at this for two days, and within five minutes after posting to stackoverflow I had an epiphany.