what are the rules for automatic django reloading when one of the code files is changed?

  • Last Update :
  • Techknowledgy :

This document contains information about mechanisms available in mod_wsgi for automatic reloading of source code when an application is changed and any issues related to those mechanisms.,What is achievable in the way of automatic source code reloading depends on which mode your WSGI application is running.,If using daemon mode, because mod_wsgi manages directly the processes handling requests and in which your WSGI application runs, there is more avenue for performing automatic source code reloading.,Using such an approach may in some cases be useful if using mod_wsgi as a development platform. It certainly would not be recommended you use this mechanism for a production system.

def application(environ, start_response):
   status = '200 OK'

if not environ['mod_wsgi.process_group']:
   output = u 'EMBEDDED MODE'
   output = u 'DAEMON MODE'

response_headers = [('Content-Type', 'text/plain'),
   ('Content-Length', str(len(output)))

start_response(status, response_headers)

return [output.encode('UTF-8')]
import sys
import sys
path = '/usr/local/wsgi/modules'
if path not in sys.path:
MaxRequestsPerChild 1
if environ['mod_wsgi.process_group'] != '':
   import signal, os
os.kill(os.getpid(), signal.SIGINT)

Suggestion : 2

When DEBUG is True, the template tag includes a small script. This script connects back to the development server and will automatically reload when static assets or templates are modified, or after runserver restarts. (Detecting modification of Django templates requires Django 3.2+.) The reload only happens in the most recently opened tab.,This event source uses StreamingHttpResponse to send events to the worker. The view continues streaming events indefinitely, until disconnected. (This requires a thread and will not work if you use runserver’s --nothreading option.),The middleware automatically inserts the required script tag on HTML responses before </body> when DEBUG is True. It does so to every HTML response, meaning it will be included on Django’s debug pages, admin pages, etc. If you want more control, you can instead insert the script tag in your templates—see below.,The template tag includes a listener script on each page. This listener script starts or connects to a SharedWorker, running a worker script. The worker script then connects to the events view in Django, using an EventSource to receive server-sent events.

python - m pip install django - browser - reload
from django.urls
import include, path

urlpatterns = [
   path("__reload__/", include("django_browser_reload.urls")),
{% load django_browser_reload %}


    {% django_browser_reload_script %}
   % extends "admin/base_site.html" %

   % load django_browser_reload %

   % block extrahead %
} {
} {
   % django_browser_reload_script %
} {
   % endblock %

Suggestion : 3
$ python manage.py runserver
for file changes with StatReloader
Performing system checks...

   System check identified no issues(1 silenced).
January 20, 2021 - 04: 25: 31
Django version 3.1 .5, using settings 'db_buddy.settings'
Starting development server at http: //
   Quit the server with CONTROL - C.
diff--git a / requirements.in b / requirements.in
index c376421. .4407458 100644
-- - a / requirements.in
   ++ + b / requirements.in
@ @ - 28, 2 + 28, 3 @ @ pytest - xdist
python - dotenv +
diff--git a / requirements.txt b / requirements.txt
index 95002 f9. .5 d9073c 100644
-- - a / requirements.txt
   ++ + b / requirements.txt
@ @ - 155, 2 + 155, 4 @ @ pytz == 2020.5
# tzlocal
   pywatchman == 1.4 .1 +
   # via - r requirements.in
requests - mock == 1.8 .0
   "ignore_dirs": ["node_modules"]
$ python manage.py runserver
for file changes with WatchmanReloader
Performing system checks...

   System check identified no issues(1 silenced).
January 20, 2021 - 07: 49: 15
Django version 3.1 .5, using settings 'db_buddy.settings'
Starting development server at http: //
   Quit the server with CONTROL - C.

Suggestion : 4

Another cool Django feature is the cached template loader, which doesn’t reload and parse template files on every template render. Template parsing is a very expensive operation and uses a lot of resources. By default, Django templates are parsed on every request, but this is bad, especially during production, where you can process thousands of requests in a short span of time.,This also makes your code easier to unit test because you can test the email logic in one place, rather than repeatedly in every controller where this takes place.,Check out the cached.Loader configuration section for a good example and details on how to do this. Don’t use the loader in development mode because it doesn’t reload parsed templates from the file system; you will need to restart your project using python manage.py startapp on every template change. This can be annoying during development, but it is perfect for the production environment.,Django has a lot of other big features like a URL router that can parse incoming requests and build new URLs from a router schema. As a whole, the Django framework is a pleasant experience and whenever you need help, just read the documentation.

Check out the minimal configuration example:

from split_settings.tools
import optional, include


      # the project different envs settings optional('envs/devel/*.py'),

      for any local settings optional(‘local_settings.py '),)

Here is example structure for a portal application which has a lot of resources and Python modules.

root @c5b96c395cfb: /test# tree project/apps / portal /
   project / apps / portal / ├──__init__.py├── admin.py├── apps.py├── management│├── __init__.py│└── commands│├── __init__.py│└── update_portal_feeds.py├── migrations│└── __init__.py├── models.py├── static│└── portal│├── css│├── img│└── js├── templates│└── portal│└── index.html├── templatetags│├── __init__.py│└── portal.py├── tests.py├── urls.py└── views.py

11 directories, 14 files

You’ll end up with a project structure like this:

root @c5b96c395cfb: /test# tree -L 3
   .├──deploy│├── chef│└── docker│├── devel│└── production├── docs├── logs├── manage.py├── media├── project│├── __init__.py│├── apps││├── auth││├── blog││├── faq││├── pages││├── portal││└── users│├── conf│├── settings.py│├── static│├── templates│├── urls.py│└── wsgi.py└── static└── admin├── css├── fonts├── img└── js

25 directories, 5 files

Suggestion : 5

Live code reloading is a simple yet effective way for developers to get quick feedback on code changes. While Django provides this functionality out-of-the-box, Celery does not. So, you'll have to manually restart the workers every time you make code changes to a task, which can make for a very difficult developer experience.,The worker should restart automatically when the Django autoreload utility is triggered on changes to the codebase.,Watchdog, a helpful tool for monitoring file system events, provides a shell utility called watchmedo that can be used to restart Celery workers based on file changes.,Describe two solutions for solving the Celery worker auto-reload problem so that when changes are made to the codebase Celery workers are restarted

$ pip install watchdog argh PyYAML
$ celery - A django_celery_example worker--loglevel = info
$ watchmedo auto - restart - d django_celery_example / -p '*.py'--celery - A django_celery_example worker--loglevel = info
$ watchmedo auto - restart--help`
on_any_event(self=<watchdog.tricks.AutoRestartTrick object at 0x105a4e490>, event=<FileModifiedEvent: src_path='django_celery_example/celery.py'>)

      worker: Hitting Ctrl+C again will terminate all running tasks!

      worker: Warm shutdown (MainProcess)
argh == 0.26 .2
PyYAML == 6.0
watchdog == 2.1 .6

Suggestion : 6

Run pip freeze, and then save the output to a file named requirements.txt., Run pip freeze, and then save the output to a file named requirements.txt. (eb-virt) ~/ebdjango$ pip freeze > requirements.txt Elastic Beanstalk uses requirements.txt to determine which package to install on the EC2 instances that run your application. ,Elastic Beanstalk uses requirements.txt to determine which package to install on the EC2 instances that run your application.,Next, you'll create your application environment and deploy your configured application with Elastic Beanstalk.

~$ virtualenv~/eb-virt
C: \ > virtualenv % HOMEPATH % \eb - virt
~$ source~/eb-virt/bin / activate(eb - virt) ~$
C: \ > % HOMEPATH % \eb - virt\ Scripts\ activate(eb - virt) C: \ >

Use pip to install Django.

(eb - virt) ~$ pip install django == 2.2

To verify that Django is installed, enter the following.

(eb - virt) ~$ pip freeze
Django == 2.2