I'm working on a Django webapp that's running under nginx and uWSGI. When I deploy new Django code (e.g., settings.py), do I need to restart uWSGI? If so, why?
Background: I had a scenario where I updated settings.py and some other code and deployed it. I did not see the changes in the webapp behavior until I restarted uWSGI.
Yes, you need to restart the uWSGI process.
Python keeps the compiled code in memory so it won't get re-read until the process restarts. The django development server (manage.py runserver) actively monitors files for changes, but that won't happen by default with other servers. If you want to enable automatic reloading in uWSGI, the touch-reload and py-auto-reload uWSGI arguments might help.
Related
I'm using Djnago 1.8.17. I have deployed the code to a remote server, checked that it is up to date, but the changes do not refresh in the web page.
Things I've tried so far:
Restarted gunicorn and nginx
Using manage.py instead of gunicorn
Clear memcached
Restarted server
Delete all .pyc files
Open in incognito
I've this module that is working fine in other servers, but for some reason this one is showing an old version.
The problem may come from static files
https://docs.djangoproject.com/en/1.8/ref/contrib/staticfiles/
you try to update them with
python manage.py collectstatic
In all standard django productions setup templates I've seen, gunicorn is run with supervisor, whereas nginx/postgres are not configured under supervisor.
Any reason? Is this required for a production system? If not, why not?
In this architecture, Gunicorn works as the application server which runs our Django code. Supervisor is just a process management utility which restarts the Gunicorn server if it crashes. The Gunicorn server may crash due to our bad code, but nginx and postgres remain intact. So in the basic config we only look after the gunicorn process through supervisor. Though we could do the same for nginx and postgres too.
You need supervisor for gunicorn because it's an simply server without any tools to restart it, run it at system startup, stop it at system shutdown or reload when it crashes.
Postgresql and nginx can take care of themselves in that aspect, so there is no need for them to be running under supervisor.
Actually, you can just use init.d, upstart or system.d to start, stop and restart gunicorn, supervisor is just easier way to handle such small servers like gunicorn.
Consider also that it is common to run multiple django apps on one system, and that requires multiple separated instances of gunicorn. Supervisor will handle them better than init, upstart or system.d
There is also uWSGI server that won't need supervisor, because it has built-in features to handle multiple instances, starting, stopping and also auto-reloading on code change. Look at uWSGI emperor system.
What is the best practice when I have an update for my Django app pushed in my production? Shall I restart both gunicorn and nginx services, with
sudo service gunicorn restart
sudo service nginx restart
or restarting only gunicorn is enough? Finally does the order of the restarts makes any difference if I have to do both the restarts? Thanks!
It entirely depends on how you've configured your box.
To keep downtime to an absolute minimum, I actually load my new release into a different directory on the box while the old release is still running. I create a new virtual environment based on my new release's requirements.txt. Then I start a second instance of gunicorn with the new release running in it (done via supervisord with entries in supervisord.conf), and leave the old instance still running.
I then update my nginx vhost file to point the server to the new release's gunicorn socket, and finally reload nginx. I do a quick check that the new site is up and functioning, and then I stop the old gunicorn instance. If for some reason it's not responding, I switch my nginx config back to point to the old one again, and then go figure out what's wrong.
I do all this using an Ansible script, but here's a great article with some Fabric scripts to do something similar: https://medium.com/#healthchecks/deploying-a-django-app-with-no-downtime-f4e02738ab06
If, on the other hand, you just update your code in-place, then there should be no changes needed to your nginx config, so you shouldn't need to reload it. Just reload gunicorn and you're good to go.
After changing the view function without runserver again, and press F5 to refresh the page, Django will not reload the new view but use the previous one. but if you change the template, Django always uses the new one.
So, Is there a way to make Django reload the view every time the user refresh the page, I think that is very convenient for develop to modify the view function frequently.
If you are running django using the dev server (./manage.py runserver) then it will always reload when it detects any code changes. This is even more efficient than reloading with every request. If you make a change, it reloads when it needs to.
If you are running a production server (nginx, apache, etc) and you want code-reload, then you need to add something to your wsgi module to detect code changes.
Code reloading with apache: http://code.google.com/p/modwsgi/wiki/ReloadingSourceCode
Code reloading with uwsgi: http://projects.unbit.it/uwsgi/wiki/TipsAndTricks
It is a known issue with PyDev. I would suggest running the server from terminal/cmd.
cd to your project directory where manage.py is present and run the server using
python manage.py runserver
You don't need to run the project from eclipse menu.
Any changes made in eclipse would be reflected as soon as they are made.
If you are running Django as a WSGI application in daemon mode you just need to touch the wsgi.py for your site and it will reload the application next time there is a request. (So no need for any special options).
I noticed it is a setting in pyDev run configurations. I wonder why but it seems --noreload is configured by default. So I edit arguments of run settings and now the server is reloading also when editing views.
Try using gunicorn or nginx as running server... They dont restart on code change
try typing
gunicorn --bind 0.0.0.0:8080 app.wsgi:application
Essentially,
I am doing some of the development for my Django app straight on my shared server rather than on a local machine (I know that initially is the problem) however regardless, I would like to know if there is a way to restart the apache server on my shared hosted server (Bluehost) for when I modify any of the python files.
I'm not sure how the Django framework is setup, maybe restarting the webserver is not needed?
THanks!
How is the apache configured to run python codes? are you using fcgi, wsgi or something else?
What i do is, i use a fcgi process and restart fcgi process without the need to restart the webserver. In my case web server is nginx but it should be same in apache if you are using fcgi.