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Flask, Python and Socket.io: getting “RuntimeError: working outside of request context” when disconnecting from a threading.Timer

I'm trying to write a simple server that disconnects a user after a min of inactivity.
ive found a simple way of doing it with threading.Timer (restarting the timer every time there is an activity).
im getting RuntimeError when using disconnect in a Timer.
tried using app.app_context and app.test_request_context but either I don't know how and where to use them or it simply doesn't work.
server code:
from flask import Flask, request
from flask_socketio import SocketIO, emit, disconnect
from threading import Timer
app = Flask(__name__)
app.config['SECRET_KEY'] = 'secret!'
sio = SocketIO(app)
clients = {}
class Client:
def __init__(self, user, sid, client_time):
self.user = user
self.sid = sid
self.client_time = client_time
self.activity_timer = Timer(10, self.disc_after_60)
self.start_timer()
def disc_after_60(self):
disconnect(self.sid)
del clients[self.user]
def start_timer(self):
if self.activity_timer.is_alive():
self.activity_timer.cancel()
self.activity_timer.start()
else:
self.activity_timer.start()
#sio.on('register')
def handle_register(client_user, client_time):
clients[client_user] = Client(client_user, request.sid, client_time)
emit('message', ("SERVER", f"{client_user} has joined the server!"), broadcast=True)
client side I just connect using register.
the full error message:
Exception in thread Thread-8:
Traceback (most recent call last):
File "C:\Users\idshi\AppData\Local\Programs\Python\Python38-32\lib\threading.py", line 932, in _bootstrap_inner
self.run()
File "C:\Users\idshi\AppData\Local\Programs\Python\Python38-32\lib\threading.py", line 1254, in run
self.function(*self.args, **self.kwargs)
File "C:\Users\idshi\PycharmProjects\PyChat excersize\Server\fsserver.py", line 24, in disc_after_60
disconnect(self.sid)
File "C:\Users\idshi\AppData\Local\Programs\Python\Python38-32\lib\site-packages\flask_socketio\__init__.py", line 919, in disconnect
socketio = flask.current_app.extensions['socketio']
File "C:\Users\idshi\AppData\Local\Programs\Python\Python38-32\lib\site-packages\werkzeug\local.py", line 348, in __getattr__
return getattr(self._get_current_object(), name)
File "C:\Users\idshi\AppData\Local\Programs\Python\Python38-32\lib\site-packages\werkzeug\local.py", line 307, in _get_current_object
return self.__local()
File "C:\Users\idshi\AppData\Local\Programs\Python\Python38-32\lib\site-packages\flask\globals.py", line 52, in _find_app
raise RuntimeError(_app_ctx_err_msg)
RuntimeError: Working outside of application context.
This typically means that you attempted to use functionality that needed
to interface with the current application object in some way. To solve
this, set up an application context with app.app_context(). See the
documentation for more information.
I would be glad if someone can help me with this. Thanks in advance.

The disconnect() function needs to be called with an application context installed, as that's the only way to know what's the application instance.
Try this:
def disc_after_60(self):
with app.app_context():
disconnect(sid=self.sid, namespace='/')
del clients[self.user]

Celery error “Received 0x00 while expecting 0xce”

I use celery 4.3.0 and rabbitmq 3.6.6. There is also a Haproxy for balancing rabbitmq, but right now it only uses one rabbitmq node.
Timeout client/server in Haproxy 24 hours.
Sometimes I get an error and the task execution status is not returned, while the tasks continue to run:
Received 0x00 while expecting 0xce
Traceback (most recent call last):
File "/var/www/serv/app/mod_axmsg/dispatch.py", line 376, in execute
result_value = func_meta.func(*task.args_list, **task.kwargs_dict)
File "/var/www/serv/app/mod_rmc/libs/health.py", line 91, in update_all_health
health.update_all_health()
File "/var/www/serv/app/mod_core/libs/health.py", line 515, in update_all_health
result.join()
File "/usr/local/serv/lib/python3.5/site-packages/celery/result.py", line 765, in join
interval=interval, no_ack=no_ack, on_interval=on_interval,
File "/usr/local/serv/lib/python3.5/site-packages/celery/result.py", line 226, in get
on_message=on_message,
File "/usr/local/serv/lib/python3.5/site-packages/celery/backends/asynchronous.py", line 188, in wait_for_pending
for _ in self._wait_for_pending(result, **kwargs):
File "/usr/local/serv/lib/python3.5/site-packages/celery/backends/asynchronous.py", line 255, in _wait_for_pending
on_interval=on_interval):
File "/usr/local/serv/lib/python3.5/site-packages/celery/backends/asynchronous.py", line 56, in drain_events_until
yield self.wait_for(p, wait, timeout=1)
File "/usr/local/serv/lib/python3.5/site-packages/celery/backends/asynchronous.py", line 65, in wait_for
wait(timeout=timeout)
File "/usr/local/serv/lib/python3.5/site-packages/celery/backends/rpc.py", line 63, in drain_events
return self._connection.drain_events(timeout=timeout)
File "/usr/local/serv/lib/python3.5/site-packages/kombu/connection.py", line 323, in drain_events
return self.transport.drain_events(self.connection, **kwargs)
File "/usr/local/serv/lib/python3.5/site-packages/kombu/transport/pyamqp.py", line 103, in drain_events
return connection.drain_events(**kwargs)
File "/usr/local/serv/lib/python3.5/site-packages/amqp/connection.py", line 505, in drain_events
while not self.blocking_read(timeout):
File "/usr/local/serv/lib/python3.5/site-packages/amqp/connection.py", line 510, in blocking_read
frame = self.transport.read_frame()
File "/usr/local/serv/lib/python3.5/site-packages/amqp/transport.py", line 280, in read_frame
'Received {0:#04x} while expecting 0xce'.format(ch))
amqp.exceptions.UnexpectedFrame: Received 0x00 while expecting 0xce
My code: celery.py
import logging
from app import db
from celery import Celery
LOG = logging.getLogger(__name__)
def make_celery(flask_app):
broker = flask_app.config['AMQP_URL']
celery = Celery('mod_celery', broker=broker, backend="rpc://")
celery.conf.update(flask_app.config)
class ContextTask(celery.Task):
def __call__(self, *args, **kwargs):
with flask_app.app_context():
return self.run(*args, **kwargs)
celery.Task = ContextTask
return celery
def in_tx(task_function):
def tx_wrapper(*args):
try:
task_function(*args)
db.session.commit()
except Exception as ex:
msg = 'Could not execute task {}. Reason: {}.' \
.format(task_function.__name__, str(ex))
LOG.error(msg)
db.session.rollback()
return tx_wrapper
And file tasks.py
from app import celery
from .celery import in_tx
#celery.task(name='app.mod_celery.update_client_health_task')
#in_tx
def update_client_health_task(client_id):
from app.mod_core.libs.health import update_client_health
update_client_health(client_id)
What could be the problem? Please don't offer me redis.
I'm not a developer and I didn't write it the code, but I really need to figure it out. I'm new to python
Thanks.

Integrating Celery with Flask using the application factory pattern: maximum recursion depth error

I am working from the cookiecutter Flask template, which uses the application factory pattern. I had Celery working for tasks that did not use the application context, but one of my tasks does need to know it; it makes a database query and updates a database object. Right now I have not a circular import error (though I've had them with other attempts) but a maximum recursion depth error.
I consulted this blog post about how to use Celery with the application factory pattern, and I'm trying to follow this Stack Overflow answer closely, since it has a structure apparently also derived from cookiecutter Flask.
Relevant portions of my project structure:
cookiecutter_mbam
│ celeryconfig.py
│
└───cookiecutter_mbam
| __init__.py
│ app.py
│ run_celery.py
│
└───utility
| celery_utils.py
|
└───derivation
| tasks.py
|
└───storage
| tasks.py
|
└───xnat
tasks.py
__init__.py:
"""Main application package."""
from celery import Celery
celery = Celery('cookiecutter_mbam', config_source='cookiecutter_mbam.celeryconfig')
Relevant portion of app.py:
from cookiecutter_mbam import celery
def create_app(config_object='cookiecutter_mbam.settings'):
"""An application factory, as explained here: http://flask.pocoo.org/docs/patterns/appfactories/.
:param config_object: The configuration object to use.
"""
app = Flask(__name__.split('.')[0])
app.config.from_object(config_object)
init_celery(app, celery=celery)
register_extensions(app)
# ...
return app
run_celery.py:
from cookiecutter_mbam.app import create_app
from cookiecutter_mbam import celery
from cookiecutter_mbam.utility.celery_utils import init_celery
app = create_app(config_object='cookiecutter_mbam.settings')
init_celery(app, celery)
celeryconfig.py:
broker_url = 'redis://localhost:6379'
result_backend = 'redis://localhost:6379'
task_serializer = 'json'
result_serializer = 'json'
accept_content = ['json']
enable_utc = True
imports = {'cookiecutter_mbam.xnat.tasks', 'cookiecutter_mbam.storage.tasks', 'cookiecutter_mbam.derivation.tasks'}
Relevant portion of celery_utils.py:
def init_celery(app, celery):
"""Add flask app context to celery.Task"""
class ContextTask(celery.Task):
def __call__(self, *args, **kwargs):
with app.app_context():
return self.run(*args, **kwargs)
celery.Task = ContextTask
return celery
When I try to start the worker using celery -A cookiecutter_mbam.run_celery:celery worker I get a RecursionError: maximum recursion depth exceeded while calling a Python object error. (I also have tried several other ways to invoke the worker, all with the same error.) Here's an excerpt from the stack trace:
Traceback (most recent call last):
File "/Users/katie/anaconda/bin/celery", line 11, in <module>
sys.exit(main())
File "/Users/katie/anaconda/lib/python3.6/site-packages/celery/__main__.py", line 16, in main
_main()
File "/Users/katie/anaconda/lib/python3.6/site-packages/celery/bin/celery.py", line 322, in main
cmd.execute_from_commandline(argv)
File "/Users/katie/anaconda/lib/python3.6/site-packages/celery/bin/celery.py", line 496, in execute_from_commandline
super(CeleryCommand, self).execute_from_commandline(argv)))
File "/Users/katie/anaconda/lib/python3.6/site-packages/celery/bin/base.py", line 275, in execute_from_commandline
return self.handle_argv(self.prog_name, argv[1:])
File "/Users/katie/anaconda/lib/python3.6/site-packages/celery/bin/celery.py", line 488, in handle_argv
return self.execute(command, argv)
File "/Users/katie/anaconda/lib/python3.6/site-packages/celery/bin/celery.py", line 420, in execute
).run_from_argv(self.prog_name, argv[1:], command=argv[0])
File "/Users/katie/anaconda/lib/python3.6/site-packages/celery/bin/worker.py", line 221, in run_from_argv
*self.parse_options(prog_name, argv, command))
File "/Users/katie/anaconda/lib/python3.6/site-packages/celery/bin/base.py", line 398, in parse_options
self.parser = self.create_parser(prog_name, command)
File "/Users/katie/anaconda/lib/python3.6/site-packages/celery/bin/base.py", line 414, in create_parser
self.add_arguments(parser)
File "/Users/katie/anaconda/lib/python3.6/site-packages/celery/bin/worker.py", line 277, in add_arguments
default=conf.worker_state_db,
File "/Users/katie/anaconda/lib/python3.6/site-packages/celery/utils/collections.py", line 126, in __getattr__
return self[k]
File "/Users/katie/anaconda/lib/python3.6/site-packages/celery/utils/collections.py", line 429, in __getitem__
return getitem(k)
File "/Users/katie/anaconda/lib/python3.6/site-packages/celery/utils/collections.py", line 278, in __getitem__
return mapping[_key]
File "/Users/katie/anaconda/lib/python3.6/collections/__init__.py", line 989, in __getitem__
if key in self.data:
File "/Users/katie/anaconda/lib/python3.6/site-packages/celery/utils/collections.py", line 126, in __getattr__
return self[k]
File "/Users/katie/anaconda/lib/python3.6/collections/__init__.py", line 989, in __getitem__
if key in self.data:
File "/Users/katie/anaconda/lib/python3.6/site-packages/celery/utils/collections.py", line 126, in __getattr__
return self[k]
I understand the basic sense of this error -- something is calling itself infinitely. Maybe create_app. But I can't see why, and I don't know how to go about debugging this.
I'm also getting this when I try to load my site:
File "~/cookiecutter_mbam/cookiecutter_mbam/xnat/tasks.py", line 14, in <module>
#celery.task
AttributeError: module 'cookiecutter_mbam.celery' has no attribute 'task'
I did not have this problem when I was using the make_celery method described here, but that method creates circular import problems when you need your tasks to access the application context. Pointers on how to do this correctly with the Cookiecutter Flask template would be much appreciated.

I'm suspicious of that bit of code that's making the Flask app available to celery. It's skipping over some essential code by going directly to run(). (See https://github.com/celery/celery/blob/master/celery/app/task.py#L387)
Try calling the inherited __call__. Here's a snippet from one of my (working) apps.
# Arrange for tasks to have access to the Flask app
TaskBase = celery.Task
class ContextTask(TaskBase):
def __call__(self, *args, **kwargs):
with app.app_context():
return TaskBase.__call__(self, *args, **kwargs) ## << here
celery.Task = ContextTask
I also don't see where you're creating an instance of Celery and configuring it. I assume you have
celery = Celery(__name__)
and then need to
celery.config_from_object(...)
from somewhere within init_celery()

This is solved. I had my configcelery.py in the wrong place. I needed to move it to the package directory, not the parent repo directory. It is incredibly unintuitive/uninformative that a misplaced config file, rather than causing an "I can't find that file"-type error, causes an infinite recursion. But at least I finally saw it and corrected it.

Flask - Not bounded to current context

I am trying to write a class, ChangeBackStatusOnErrorTask which does exactly as its name implies.
class ChangeBackStatusOnErrorTask(Task):
abstract = True
def on_failure(self, exc, task_id, args, kwargs, einfo):
server = Server.query.get(server_id)
server.status = RemoteStatus.ERROR
db.session.commit()
#celery.task(bind=True, base=ChangeBackStatusOnErrorTask)
def deploy_server(self, server_id):
try:
server.status = RemoteStatus.LAUNCHING
db.session.commit()
host = server.ssh_user + '#' + server.ip
execute(fabric_deploy_server, self, server, hosts=host)
server.status = RemoteStatus.LAUNCHED
db.session.commit()
except Exception as e:
server.status = RemoteStatus.ERROR
db.session.commit()
traceback.print_exc()
raise e
However, this code is not working due to the fact that ChangeBackStatusOnErrorTask is not bounded to my Flask context:
File "/Users/vng/.virtualenvs/AutomataHeroku/lib/python2.7/site-packages/celery/app/trace.py", line 367, in trace_task
R = retval = fun(*args, **kwargs)
File "/Users/vng/.virtualenvs/AutomataHeroku/lib/python2.7/site-packages/celery/app/trace.py", line 622, in __protected_call__
return self.run(*args, **kwargs)
File "/Users/vng/Dropbox/Code/Affiliate/AutomataHeroku/automata/server/tasks.py", line 59, in deploy_server
server = Server.query.get(server_id)
File "/Users/vng/.virtualenvs/AutomataHeroku/lib/python2.7/site-packages/flask_sqlalchemy/__init__.py", line 498, in __get__
return type.query_class(mapper, session=self.sa.session())
File "/Users/vng/.virtualenvs/AutomataHeroku/lib/python2.7/site-packages/sqlalchemy/orm/scoping.py", line 78, in __call__
return self.registry()
File "/Users/vng/.virtualenvs/AutomataHeroku/lib/python2.7/site-packages/sqlalchemy/util/_collections.py", line 990, in __call__
return self.registry.setdefault(key, self.createfunc())
File "/Users/vng/.virtualenvs/AutomataHeroku/lib/python2.7/site-packages/sqlalchemy/orm/session.py", line 2861, in __call__
return self.class_(**local_kw)
File "/Users/vng/.virtualenvs/AutomataHeroku/lib/python2.7/site-packages/flask_sqlalchemy/__init__.py", line 143, in __init__
self.app = app = db.get_app()
File "/Users/vng/.virtualenvs/AutomataHeroku/lib/python2.7/site-packages/flask_sqlalchemy/__init__.py", line 957, in get_app
'application not registered on db instance and no application'
RuntimeError: application not registered on db instance and no application bound to current context
How can I fix this?

I will assume that you use sqlachemy and the flask-sqlalchemy extension. And that you get your db object from some dedicated module and this object is also bound to the flask instance(please edit your question to clarify those point).
Inside your app module declare your celery config:
app = Flask(__name__)
app.config[CELERY_BROKER_URL] = 'redis://localhost:6379'
app.config[CELERY_RESULT_BACKEND] = 'redis://localhost:6379'
Then inside your celery module you need to bound it to flask:
from celery import Celery
from app import current_app as app
def bound_celery(app):
celery = Celery(
app.import_name,
backend=app.config['CELERY_RESULT_BACKEND'],
broker=app.config['CELERY_BROKER_URL']
)
celery.conf.update(app.config)
TaskBase = celery.Task
class ContextTask(TaskBase):
abstract = True
def __call__(self, *args, **kwargs):
with app.app_context():
return TaskBase.__call__(self, *args, **kwargs)
celery.Task = ContextTask
return celery
celery = bound_celery(app)
And finally use the celery created object to decorate your tasks:
#celery.task(bind=True, base=ChangeBackStatusOnErrorTask)
def deploy_server(self, server_id):
...
Source: flask doc

Connection is closed when a SQLAlchemy event triggers a Celery task

When one of my unit tests deletes a SQLAlchemy object, the object triggers an after_delete event which triggers a Celery task to delete a file from the drive.
The task is CELERY_ALWAYS_EAGER = True when testing.
gist to reproduce the issue easily
The example has two tests. One triggers the task in the event, the other outside the event. Only the one in the event closes the connection.
To quickly reproduce the error you can run:
git clone https://gist.github.com/5762792fc1d628843697.git
cd 5762792fc1d628843697
virtualenv venv
. venv/bin/activate
pip install -r requirements.txt
python test.py
The stack:
$ python test.py
E
======================================================================
ERROR: test_delete_task (__main__.CeleryTestCase)
----------------------------------------------------------------------
Traceback (most recent call last):
File "test.py", line 73, in test_delete_task
db.session.commit()
File "/home/brice/Code/5762792fc1d628843697/venv/local/lib/python2.7/site-packages/sqlalchemy/orm/scoping.py", line 150, in do
return getattr(self.registry(), name)(*args, **kwargs)
File "/home/brice/Code/5762792fc1d628843697/venv/local/lib/python2.7/site-packages/sqlalchemy/orm/session.py", line 776, in commit
self.transaction.commit()
File "/home/brice/Code/5762792fc1d628843697/venv/local/lib/python2.7/site-packages/sqlalchemy/orm/session.py", line 377, in commit
self._prepare_impl()
File "/home/brice/Code/5762792fc1d628843697/venv/local/lib/python2.7/site-packages/sqlalchemy/orm/session.py", line 357, in _prepare_impl
self.session.flush()
File "/home/brice/Code/5762792fc1d628843697/venv/local/lib/python2.7/site-packages/sqlalchemy/orm/session.py", line 1919, in flush
self._flush(objects)
File "/home/brice/Code/5762792fc1d628843697/venv/local/lib/python2.7/site-packages/sqlalchemy/orm/session.py", line 2037, in _flush
transaction.rollback(_capture_exception=True)
File "/home/brice/Code/5762792fc1d628843697/venv/local/lib/python2.7/site-packages/sqlalchemy/util/langhelpers.py", line 63, in __exit__
compat.reraise(type_, value, traceback)
File "/home/brice/Code/5762792fc1d628843697/venv/local/lib/python2.7/site-packages/sqlalchemy/orm/session.py", line 2037, in _flush
transaction.rollback(_capture_exception=True)
File "/home/brice/Code/5762792fc1d628843697/venv/local/lib/python2.7/site-packages/sqlalchemy/orm/session.py", line 393, in rollback
self._assert_active(prepared_ok=True, rollback_ok=True)
File "/home/brice/Code/5762792fc1d628843697/venv/local/lib/python2.7/site-packages/sqlalchemy/orm/session.py", line 223, in _assert_active
raise sa_exc.ResourceClosedError(closed_msg)
ResourceClosedError: This transaction is closed
----------------------------------------------------------------------
Ran 1 test in 0.014s
FAILED (errors=1)

I think I found the problem - it's in how you set up your Celery task. If you remove the app context call from your celery setup, everything runs fine:
class ContextTask(TaskBase):
abstract = True
def __call__(self, *args, **kwargs):
# deleted --> with app.app_context():
return TaskBase.__call__(self, *args, **kwargs)
There's a big warning in the SQLAlchemy docs about never modifying the session during after_delete events: http://docs.sqlalchemy.org/en/latest/orm/events.html#sqlalchemy.orm.events.MapperEvents.after_delete
So I suspect the with app.app_context(): is being called during the delete, trying to attach to and/or modify the session that Flask-SQLAlchemy stores in the app object, and therefore the whole thing is bombing.
Flask-SQlAlchemy does a lot of magic behind the scenes for you, but you can bypass this and use SQLAlchemy directly. If you need to talk to the database during the delete event, you can create a new session to the db:
#celery.task()
def my_task():
# obviously here I create a new object
session = db.create_scoped_session()
session.add(User(id=13, value="random string"))
session.commit()
return
But it sounds like you don't need this, you're just trying to delete an image path. In that case, I would just change your task so it takes a path:
# instance will call the task
#event.listens_for(User, "after_delete")
def after_delete(mapper, connection, target):
my_task.delay(target.value)
#celery.task()
def my_task(image_path):
os.remove(image_path)
Hopefully that's helpful - let me know if any of that doesn't work for you. Thanks for the very detailed setup, it really helped in debugging.

Similar to the answer suggested by deBrice, but using the approach similar to Rachel.
class ContextTask(TaskBase):
abstract = True
def __call__(self, *args, **kwargs):
import flask
# tests will be run in unittest app context
if flask.current_app:
return TaskBase.__call__(self, *args, **kwargs)
else:
# actual workers need to enter worker app context
with app.app_context():
return TaskBase.__call__(self, *args, **kwargs)

Ask, the creator of celery, suggested that solution on github
from celery import signals
def make_celery(app):
...
#signals.task_prerun.connect
def add_task_flask_context(sender, **kwargs):
if not sender.request.is_eager:
sender.request.flask_context = app.app_context().__enter__()
#signals.task_postrun.connect
def cleanup_task_flask_context(sender, **kwargs):
flask_context = getattr(sender.request, 'flask_context', None)
if flask_context is not None:
flask_context.__exit__(None, None, None)