Develop Reference

celery with Django

I am building a app and I am trying to run some tasks everyday. So I saw some answers, blogs and tutorials about using celery, So I liked the idea of using celery for doing background jobs.
But I have some questions about celery :-
As mentioned in Celery Documentation that after setting a celery task , I have to run a command like celery -A proj worker -l INFO which will process all the tasks and after command it will run the tasks, so my question is , I have to stop the running server to execute this command and
what if I deploy Django project with celery on Heroku or Python Anywhere.
Should I have to run command every time Or I can execute this command first then i can start the server ?
If I have to run this command every time to perform background tasks then how is this possible when deploying to Heroku,
Will celery's background tasks will remain running after executing python manage.py run server in only terminal ?
Why I am in doubt ? :-
What I think is, When running celery -A proj worker -l INFO it will process (or Run) the tasks and I cannot execute run server in one terminal.
Any help would be much Appreciated. Thank You

Should I have to run command every time Or I can execute this command first then i can start the server ?
Dockerize your Celecry and write your own script for auto-run.

You can't run celery worker and django application in one terminal simultaneously, because both of them are programs that should be running in parallel. So you should use two terminals, one for django and another for celery worker.
I highly recommend to read this heroku development article for using Celery and Django on heroku.

Deploy django project with celery

After I deploy my django project, all I need is touch uwsgi_touch file. And uwsgi will gracefully restart its workers. But what about celery? Now I just restart celery manually when code base of celery tasks is changed. But even if I do it manually I still can't be sure that I will not kill celery task.
Any solutions?

A better way to manage celery workers is to use supervisor
$ pip install supervisor
$ cd /path/to/your/project
$ echo_supervisord_conf > supervisord.conf
Add these to your supervisord.conf file
[program:celeryworker]
command=/path/to/celery worker -A yourapp -l info
stdout_logfile=/path/to/your/logs/celeryd.log
stderr_logfile=/path/to/your/logs/celeryd.log
Now start supervisor with supervisord command in your terminal & use supervisorctl to manage process.
To restart you can do
$ supervisorctl restart celeryworker

I've found answer in celery FAQ
http://docs.celeryproject.org/en/2.2/faq.html#how-do-i-shut-down-celeryd-safely
Use the TERM signal, and the worker will finish all currently
executing jobs and shut down as soon as possible. No tasks should be
lost.
You should never stop celeryd with the KILL signal (-9), unless you’ve
tried TERM a few times and waited a few minutes to let it get a chance
to shut down. As if you do tasks may be terminated mid-execution, and
they will not be re-run unless you have the acks_late option set
(Task.acks_late / CELERY_ACKS_LATE).

Starting Celery on openshift

I'm currently writing a flask application and going to use openshift. I start my worker in my dev environment using
celery worker -A wsgi.app
My question is how do I start my celery worker in openshift? Because if I started in the openshift shell when I exit the shell the process is killed and my background workers never run so the flask application never runs correctly.
I really appreciate any help. Thanks.

Why can't try like this
celery multi start worker1 \
--pidfile="$HOME/run/celery/%n.pid" \
--logfile="$HOME/log/celery/%n.log"
where mentioned here

Celery worker working from command line but not as daemon, in a virtualenv

System Info
Ubuntu 12.04 LTS
Django 1.5.5
Python 2.7.3
Celery 3.1.9
I am running this on a vagrant virtual machine (with puppet) and attempting to set up celery to run the worker as a daemon as described in the celery docs here as well as the celery setup for django described here. I am using a virtualenv for the project located at
/home/vagrant/virtualenvs/myproj
The actual project files are located at
/srv/myproj
I have been able to start the the worker and the beat scheduler without issue when located in the /srv/myproj directory using the command line statements.
~/virtualenvs/myproj/bin/celery -A app beat
~/virtualenvs/myproj/bin/celery worker -A app
Both beat and the worker start without issue and the scheduled task is passed to the worker and executed. The problem arises when I attempt to attempt to run them as background processes. I am using the scripts found on the celery github repo in /etc/init.d/ and using the following configuration settings in my celeryd and celerybeat files located in /etc/default
CELERY_BIN="/home/vagrant/virtualenvs/myproj/bin/celery"
CELERYD_CHDIR="/srv/myproj"
Attempting to run the services as sudo with
sudo service celeryd start
sudo service celerybeat start
Causes an error message to be thrown, I believe this is because it is using the python located in usr/lib instead of the python in the virtualenv. The error thrown is a cannot import name (the package exists in the virtualenv but not globally hence my assumption).
I also noticed on the Running the worker as a daemon it states that workers should run as unprivileged users, and that you should start workers and beat as using the multi or
--detach command. This way I was able to start the worker (not beat) but all the .log and .pid files are being created in my current directory instead of where I've specified in the /etc/default/celeryd config file.
Does anyone have a solution for getting celery to work in a virtualenv? I feel like I'm really close and am overlooking some simple part of the configuration.

I was eventually able to get this working by using supervisor and setting the environment variables in the [program:celery] environment option.

Upstart job to run Celery doesn't stop all the worker processes

I have written an Upstart job to run celery in my Ubuntu server. Here's my configuration file called celeryd.conf
# celeryd - runs the celery daemon
#
# This task is run on startup to run the celery daemon
description "run celery daemon"
start on startup
expect fork
respawn
exec su - trakklr -c "/app/trakklr/src/trakklr celeryd --events --beat --loglevel=debug --settings=production"
When I execute sudo service celeryd start, the celeryd process starts just fine and all the x number of worker process start fine.
..but when I execute, sudo service celeryd stop, it stops most of the processes but a few processes are left hanging.
Why is this happening? I'm using Celery 2.5.3.
Here's an issue from the Github tracker.
https://github.com/celery/django-celery/issues/142

I still use init.d to run celery so this may not apply. With that in mind, stopping the celery service sends the TERM signal to celery. This tells the workers not to accept new tasks but it does not terminate existing tasks. Therefore, depending on how long your tasks take to execute you may see tasks for some time after telling celery to stop. Eventually, they will all shut down unless you have some other problem.

I wasn't able to figure this out but it seemed to be an issue with my older celery version. I found this issue mentioned on their issue-tracker and I guess it points to the same issue:
https://github.com/celery/django-celery/issues/142
I upgraded my celery and django-celery to the 3.x.x versions and this issue was gone.