Django cheatsheet

# Create et access project folder
~$  mkdir project_name
~$  cd project_name

# Create Python virtual env
~$  python3 -m venv venv

# Activate virtual env
~$  source venv/bin/activate

# If you want to deactivate virtual env
~$  deactivate

# Install django (~= same as 4.2.*)
~$  pip install django~=4.2.0

# New django project (from project_name folder)
~$  django-admin startproject config

# Create app (from project_name folder)
~$  python manage.py startapp app_name

Django create a database table for each models present in your app using those commands:

Makemigrations: Create a file under app_name/migrations with the database structure to create

~$  python manage.py makemigrations

Migrate: Will read the migrations files and create the actual database and tables

~$  python manage.py migrate

~$  python manage.py createsuperuser

~$  python manage.py runserver  => ex.  http://127.0.0.1:8000

# Create a requirements file that contain all your project dependencies
~$  pip freeze > requirements.txt

# Install your project requirements (if a requirements file exist)
~$  pip install -r requirements.txt

# Django shell (Run project code directly)
~$ python manage.py shell

# example of code to run in the shell:
 >>> from app_name.models import User
 >>> user1 = User.objects.first()

# Prepare static folders for production
~$ python manage.py collectstatic

# Take all data from app blog and export in json
~$ python manage.py dumpdata blog > myapp.json

# Take all data in json file and import in app data table
~$ python manage.py loaddata myapp.json

# To Create or Update a message file for Translation, run this command
~$ django-admin makemessages -l de
# Updating message files
~$ django-admin compilemessages

Keyword	Description
contains	Contains the phrase
icontains	Same as contains, but case-insensitive
date	Matches a date
day	Matches a date (day of month, 1-31) (for dates)
endswith	Ends with
iendswith	Same as endswidth, but case-insensitive
exact	An exact match
iexact	Same as exact, but case-insensitive
in	Matches one of the values
isnull	Matches NULL values
gt	Greater than
gte	Greater than, or equal to
hour	Matches an hour (for datetimes)
lt	Less than
lte	Less than, or equal to
minute	Matches a minute (for datetimes)
month	Matches a month (for dates)
quarter	Matches a quarter of the year (1-4) (for dates)
range	Match between
regex	Matches a regular expression
iregex	Same as regex, but case-insensitive
second	Matches a second (for datetimes)
startswith	Starts with
istartswith	Same as startswith, but case-insensitive
time	Matches a time (for datetimes)
week	Matches a week number (1-53) (for dates)
week_day	Matches a day of week (1-7) 1 is Sunday
iso_week_day	Matches a ISO 8601 day of week (1-7) 1 is Monday
year	Matches a year (for dates)
iso_year	Matches an ISO 8601 year (for dates)

Django routing info is store in project_folder/urls.py file

from django.contrib import admin
from django.urls import path, include

urlpatterns = [
    path('admin/', admin.site.urls), # pre-created admin urls routes
    path('', include('app_name.urls')) # include your app urls
]

The 'include()' method allow to link another urls.py file created in your app folder (app_name/urls.py)

from django.urls import path
from app_name import views

urlpatterns = [
    path('posts', views.index, name='posts.index'),
    path('posts/create/', views.create, name='posts.create',
    path('posts/<int:id>/', views.show, name='posts.show'),
    path('posts/<int:id>/edit/', views.edit, name='posts.edit'),
    path('posts/<int:id>/delete/', views.delete, name='posts.delete'),
    path('posts/<int:id>/<int:state>/', views.status, name='posts.status'), # two arguments
]

Templates are store in project_folder/templates or in your app_folder/templates/app_name/*.html

<!-- Extend from another template -->
<!-- can use the same parts of your HTML for different template -->
{% extends 'base.html' %}

<!-- A part of the parent template that is defined and is replaced by a part in the child template -->
{% block contents %} {% endblock contents %}

<!-- include template-->
{% include 'partials/header.html' %}
<!-- include template with One or More Parameters -->
{% include 'body.html' with key1=value1 key2=value2 %}

<!-- If statement in template -->
{% if user.username = 'Mike' %}
Hello Admin
{% elif user.username = 'john' %}
Hello John Doe
{% else %}
Hello User
{% endif %}

<!-- for loop in template -->
{% for product in products %}
row: {{ forloop.counter }} # starting index 1 {{ forloop.counter0 }} # starting index 0
The product name is {{ product.name }}

The product name is {{ product.price }}

  {% endfor %}

  <!-- Access to the variable in the template -->
  {{ var_name }}

  <!-- Template variables formating  -->
  {{ title | lower }} {{ blog.post | truncatwords:50 }} {{ order.date | date:"D M Y" }} {{ list_items | slice:":3" }} {{
  total | default:"nil" }}

  <!-- Current path (ex. posts/1/show) -->
  {{ request.path }}

  <!-- URL by name with param -->
  {% url 'posts.delete' id=post.id %}

  <!-- Use static in template: -->
  {% load static %} {% static 'css/main.css' %}

  <!-- Define the variable in the template -->
  {% with name="World" %}
  
    
Hello {{ name }}!
  
  {% endwith %}

  <!-- Template translate text -->
  {% load i18n %}
  <title>{% trans "This is the title." %}</title>
  <!-- Use variable translate in the template -->
  <title>{% trans object.title %}</title>

  <!-- Define the list in the template -->
  <input type="number" <!--swig29-->>

  <!-- Safely Pass Data to JavaScript in a Django Template: -->
  <!--+ Use data attributes for simple values -->
  <script data-username="{{ username }}">
    const data = document.currentScript.dataset;
    const username = data.username;
  </script>

  <!-- + Separate script files: can use document.currentScript for separate script files -->
  <script src="{% static 'index.js' %}" data-username="{{ username }}"></script>

  <!-- + Case conversion -->
  <script src="{% static 'index.js' %}" data-full-name="{{ full_name }}"></script>
  <!--  Read it in JavaScript as fullName: -->
  <script>
    const data = document.currentScript.dataset;
    const fullName = data.fullName;
  </script>

  <!-- + Non-string types -->
  <script src="{% static 'index.js' %}" data-follower-count="{{ follower_count }}"></script>

  <!--  parseInt() to convert this value from a string: -->
  <script>
    const data = document.currentScript.dataset;
    const followerCount = parseInt(data.followerCount, 10);
  </script>

  <!-- + There’s no limit: A <script> can have as many data attributes as you like: -->
  <script
    src="{% static 'index.js' %}"
    defer
    data-settings-url="{% url 'settings' %}"
    data-configuration-url="{% url 'configuration' %}"
    data-options-url="{% url 'options' %}"
    data-preferences-url="{% url 'preferences' %}"
    data-setup-url="{% url 'setup' %}"
  ></script>
</p>

For example, if your custom tags/filters are in a file called basetags.py, your app layout might look like this:

app_name/
└─── templatetags/
     └─── basetags.py
     __init__.py
     models.py
     views.py

• And in your template you would use the following:

{% load basetags %}

• the module must contain a module-level variable named register that is a template.Library instance, in which all the tags and filters are registered. So, near the top of your module, put the following:

Custom filters are Python functions that take one or two arguments: The value of the variable (input) – not necessarily a string. The value of the argument – this can have a default value, or be left out altogether. For example, in the filter {{ var|foo:"bar" }}, the filter foo would be passed the variable var and the argument "bar".

The Library.filter() method takes two arguments: The name of the filter – a string. The compilation function – a Python function (not the name of the function as a string). You can use register.filter() as a decorator instead:

# basetags.py
from django import template

register = template.Library()

@register.filter(name="cut")
def cut(value, arg):
    """Removes all values of arg from the given string"""
    return value.replace(arg, "")

# Most filters don’t take arguments. In this case, leave the argument out of your function
@register.filter()
def lower(value): # Only one argument.
    """Converts a string into all lowercase"""
    return value.lower()


@register.simple_tag
def to_class_name(object):
    return str(object.__class__.__name__)

# Template
# And here’s an example of how that filter would be used in Template:
<!--swig18-->

# Put the result of simple tag into a variable
<!--swig54-->
<p>Model Class Name: <!--swig19--></p>

Model manager allow model database reads and writes

# One line create and save
Article.objects.create(name='Item 1', price=19.95)

# Read all
Article.objects.all()

# Create
user = User.objects.first()
article = Article(user=user, name='Item 1', price=19.95)

# Save
article.save()

# Read one
Article.objects.get(id=1)

# Select Related (to avoid n+1 query)
posts = Post.objects.select_related('user', 'category').all()

# Read or render a 404 not found page
from django.shortcuts import get_object_or_404
article = get_object_or_404(Article, id=512)

# Filter
Article.objects.filter(model='dyson', name__icontains='dyson') # __icontains
Article.objects.filter(year__gt=2016) # __gt = greater than
Article.objects.filter(year__lt=2001) # __lt = less than

# Filter on relationship sub model field
Article.objects.get(user__username='mike')

# Ordering
Article.objects.order_by('name')     # ascending
Article.objects.order_by('-name')   # descending

# Slicing return first
Article.objects.all().order_by('name')[0]

# Slicing return last
Article.objects.all().order_by('-name')[0]

# Slicing limit/offset
Article.objects.all().order_by('name')[1..10]

# Updating
article = Article.objects.first()
article.name = 'new name'
article.save()

# One line update
Article.objects.filter(id=4).update(name='new name')

# Deleting
article = Article.objects.first()
article.delete()

# One line delete
article.objects.get(id=1).delete()

# Delete all
Article.objects.all().delete()

# Set ForeignKey field value
model1 = Model(name='dyson')
article.model = model1

# Get ForeignKey value
article1.model.name
model1.article_set.all()

# Add Many-to-Many
article1.tags.add(tag1)
article1.tags.all()
tag1.articles_set.all()

# forms.py
from django.core.exceptions import ValidationError

# field validation
def clean_first_name(self):
    data = self.cleaned_data['first_name']
    if data = 'Mike':
        raise ValidationError('Your name must not be Mike')
    return data

# form validation
def clean(self):
    first_name = self.cleaned_data['first_name']
    last_name = self.cleaned_data['last_name']
    if first_name + last_name = 'MikeTaylor':
        raise ValidationError('Your name must not be Mike Taylor')

User Model (pre-created)

# Get a reference to Django pre-created User model
from django.contrib.auth import get_user_model

User = get_user_model()

# Or if you want to custom user model
from django.contrib.auth.models import AbstractUser

class User(AbstractUser):
    # add custom fields and methods

# To make Django use that model go to settings.py and add: AUTH_USER_MODEL = 'app_name.User'

# LoginView is already pre-created by Django
from django.contrib.auth.views import LoginView

# Add a url to reach that view
path('login/', LoginView.as_view(), name='login')

# By default the LoginView will try to open a template name 'registration/login.html' and send a login form with it.

<!-- Create a template under registration/login.html -->
{% extends "base.html" %} {% block content %}
<form method="post">
  {% csrf_token %} {{ form }}
  <button type="submit">Login</button>
</form>
{% endblock content %}

<!-- When user click the Login button, the LoginView will try to authenticate the user with the form username ans password -->

<!-- If successful il will then login the user and redirect to LOGIN_REDIRECT_URL specified in your settings.py -->

#Authentication : LogoutView

# LogoutView is already pre-created by Django
from django.contrib.auth.views import LogoutView

# Add a url to reach that view
path('logout/', LoginView.as_view(), name='logout')

# Include a link in a template
<a> href="{% url 'logout' %}">Logout</a>

# After link is execute, the user will be logout and redirect to LOGOUT_REDIRECT_URL specified in your settings.py

#Authentication : SignupView

# Create a SignupView (that view is not created by default)
# import sinupview form pre-created by Django
from django.contrib.auth.forms import UserCreationForm
from django.views.generic import CreateView

class SignupView(CreateView):
    template_name = 'registration/signup.html'
    form_class = UserCreationForm

    def get_success_url(self):
        return reverse("login")

<!-- Create template: registration/signup.html -->
{% extends "base.html" %} {% block content %}
<form method="post">
  {% csrf_token %} {{ form }}
  <button type="submit">Signup</button>
</form>
{% endblock content %}

# Add a url to reach that view
from posts.views import SignupView

path('signup/', SignupView.as_view(), name='signup')

# Optional: Customize the UserCreationForm
# (forms.py)
from django.contrib.auth import get_user_model
from django.contrib.auth.forms import UserCreationForm

User = get_user_model()
class CustomUserCreationForm(UserCreattionForm):
    class Meta:
        model = User
        fields = ['username']
        fields_classes = {'username': UsernameField}

#Optional pre-created Authentication routes

# urls.py
urlpatterns += path('', include('django.contrib.auth.urls'))
# /login, /lougout, /signup, etc.

#Template Authentication helpers

<!-- Authentication links -->
<a href="{% url 'login' %}">Login</a>
<a href="{% url 'signup' %}">Signup</a>
<a href="{% url 'logout' %}">Logout</a>

<!-- Check if user login -->
{% if request.user.is_authenticated %} Logged in as: {{ request.user.username }} {% endif %}

#Authorization: LoginRequiredMixin and login_required

from django.contrib.auth.mixins import LoginRequiredMixin

# Restrict views to auth user only (views.py)
class PostsCreateView(LoginRequiredMixin, generic.CreateView):
    ...
    ...


from django.contrib.auth.decorators import login_required

@login_required(login_url='/login')
def search_page(request):
    ...
    ...

#Manual Authentication , Login and Logout

from django.contrib.auth import authenticate, login

def login_page(request):
    if request.method == "POST":
        username = request.POST.get("username")
        password = request.POST.get("password")
        user = authenticate(request, username=username, password=password)
        if user is not None:
            login(request, user)
            return redirect("index")

return render(request, "registration/login.html", {})


def logout_page(request):
    logout(request)
    return redirect("index")

#User Change password

# set_password will hash the password
user.set_password('raw password')

$ pip install python-decouple

Create a file name '.env' in the root folder of your project

SECRET_KEY = 'your secret key'
ALLOWED_HOST = 127.0.0.1

In settings.py change security related settings to point to the .env file

from decouple import config

SECRET_KEY = config('SECRET_KEY')
ALLOWED_HOST = config('ALLOWED_HOST')

Celery is a distributed task queue that can collect, record, schedule, and perform tasks outside of your main program.

#Step 1: Install Celery Using pip

~$ pip install celery       # pip install celery[redis]

#Step 2. Add celery.py File in Your Project Module

# your_project/celery.py
import os
from celery import Celery

os.environ.setdefault('DJANGO_SETTINGS_MODULE','your_project_name.settings')
app = Celery('your_project_name')
app.config_from_object('django.conf:settings', namespace='CELERY')
app.autodiscover_tasks()

@app.task(bind=True)
def debug_task(self):
    print(f'Request: {self.request!r}')

#Step 3: Import the Celery App to Django

To ensure that the Celery app is loaded when Django starts, add the following code into the __init__.py file that sits on the project module beside on settings.py file.

# your_project/__init__.py
from .celery import app as celery_app

__all__ = ('celery_app',)

#Step 4: Download and Run Redis as a Celery ‘broker’

~$ redis-server

You can test that Redis is working properly by typing this into your terminal:

~$ redis-cli ping

Redis should reply with PONG - try it!

#Step 5: Add Redis as a Dependency in the Django Project:

~$ pip install redis

#Step 6: Celery Stuff Configure to the Django Settings File

Once Redis is up, add the following code to your settings.py file and use celery-result

~$ pip install django-celery-results

This extension enables you to store Celery task results using the Django ORM.
It defines a single model (django_celery_results.models.TaskResult) used to store task results, and you can query this database table like any other Django model.

INSTALLED_APPS = [
                … ,
                'django_celery_results',
                ]

BROKER_URL = 'redis://localhost:6379'
CELERY_RESULT_BACKEND = 'redis://localhost:6379'
CELERY_ACCEPT_CONTENT = ['application/json']
CELERY_TASK_SERIALIZER = 'json'
CELERY_RESULT_SERIALIZER = 'json'
CELERY_TIMEZONE = TIME_ZONE
CELERY_RESULT_BACKEND = 'django-db'
CELERY_CACHE_BACKEND = 'django-cache'

CACHES = {
    'default': {
        'BACKEND': 'django.core.cache.backends.db.DatabaseCache',
        'LOCATION': 'redis://localhost:6379/1',
        "OPTIONS": {
                    "CLIENT_CLASS": "django_redis.client.DefaultClient",
        }
    }
}

#That’s it! You should now be able to use Celery with Django

Test that the Celery worker is ready to receive tasks:

~$ celery -A your_project_name worker -l info

The most important task is: Always run a worker is needed to execute the celery task if any error throws from Redis like this:

AttributeError: 'str' object has no attribute 'items'

• the solution is: you have to use Redis old version

#Step 1: Add tasks.py File to Your Django App.

# app_name/tasks.py
from celery import shared_task
from celery.decorators import task
from time import sleep


@task(name='my_first_task')
def my_first_task(duration):
    sleep(duration)
    return('first_task_done')

@shared_task
def test_func():
    for i in range(10):
        print(i)
    return 'End_OK'

@shared_task
def adding(x, y):
    time.sleep(10)
    result = x + y
    return result

#Step 2: Assign Task to the Celery.

You need to assign a task to the celery. To assign this task you need to call this function with something different. celery gives us two methods delay() and apply_async() to call task.

# Normal function call in python
~$ my_first_task()

# add task to the celery with function call
~$ my_first_task.delay()

You can send argument to the function using the delay method. To check celery on the action open a separate tab of the terminal then go to the project directory (activate environment if you are using one) and run this command again

~$ celery -A your_project_name worker -l info

# app_name/views.py
from django.http import HttpResponse
from app_name.tasks import my_first_task, test_func, adding

def index(request):
    my_first_task.delay(10)
    result = adding.delay(x=4, y=5)
    return HttpResponse(f'response done. {result}')

def test(request):
    test_func.delay()
    return HttpResponse("Done")

#Then call the view from your app URL

# app_name/urls.py
from django.urls import path
from app_name.views import index, test
urlpatterns = [
    path('celery-index/', index, name='celery_index_url'),
    path('celery-test/', test, name='celery_test_url'),
]

#Step 1: Install Supervisor on Ubuntu Server

~$ sudo apt-get install supervisor

#Step 2: Add .conf File in Supervisor

~$ sudo nano /etc/supervisor/conf.d/app_name.conf

app_name can be anything you like, it should be similar to your project name.

#Step 3: Add some Configure in app_name.conf

[program:your_app_name]
command=/path/to/env/bin/celery worker -A your_project_name --loglevel=INFO
directory=/path/to/workflow/your_project_name/
user=www-data
autostart=true
autorestart=true
stdout_logfile=/path/to/workflow/your_project_name/logs/celeryd.log
redirect_stderr=true

Describe the configure file:

[program:your_app_name]
#The name of your supervisord program

command=/path/to/env/bin/celery worker -A your_project_name --loglevel=INFO
#Set full path to celery program if using virtualenv

directory=/path/to/workflow/your_project_name/
#The directory to your Django project

user=www-data
#The web server has to be run under a specific user. That user must exist.

autostart=true
#If true, this program will start automatically when supervisord is started

autorestart=true
#May be one of false, unexpected, or true. If false, the process will never be autorestarted. If unexpected, the process will be restart when the program exits with an exit code that is not one of the exit codes associated with this process’ configuration (see exitcodes). If true, the process will be unconditionally restarted when it exits, without regard to its exit code.

stdout_logfile=/path/to/workflow/your_project_name/logs/celeryd.log
#Put process stdout output in this file

redirect_stderr=true
#If true, cause the process’ stderr output to be sent back to supervisord on its stdout file descriptor (in UNIX shell terms, this is the equivalent of executing /the/program 2>&1).

#Step 4: Inform Configuration to the Server

After adding a new program, we should run the following two commands, to inform the server to reread the configuration files and to apply any changes.

~$ sudo supervisorctl reread
~$ sudo supervisorctl update

#Managing Supervisor App

~$ sudo supervisorctl

You will be greeted with a list of the registered processes. You will see a process called your_app_name with a RUNNING status.

your_app_name                 RUNNING   pid 6853, uptime 0:22:30
supervisor>

Type help for a list of available commands.

supervisor> help
default commands (type help <topic>):
=====================================
add    exit      open  reload  restart   start   tail
avail  fg        pid   remove  shutdown  status  update
clear  maintail  quit  reread  signal    stop    version

In a nutshell, we can start, stop and restart programs bypassing the program name as an argument to the respective command. We can also take a look at the program output with the tail command. Once you are finished, you can quit.

~$ supervisor> quit

#Step 1 — Installing the Packages from the Ubuntu Repositories

sudo apt update
sudo apt install python3-venv python3-dev libpq-dev postgresql postgresql-contrib nginx curl

#Step 2 — Creating the PostgreSQL Database and User

sudo -u postgres psql

• First, create a database for your project:

postgres=# CREATE DATABASE myproject;

• Next, create a database user for our project. Make sure to select a secure password:

postgres=# CREATE USER myprojectuser WITH PASSWORD 'password';

• Afterwards, you’ll modify a few of the connection parameters for the user that you just created

postgres=# ALTER ROLE myprojectuser SET client_encoding TO 'utf8';
postgres=# ALTER ROLE myprojectuser SET default_transaction_isolation TO 'read committed';
postgres=# ALTER ROLE myprojectuser SET timezone TO 'UTC';

• Now, you can give the new user access to administer the new database:

postgres=# GRANT ALL PRIVILEGES ON DATABASE myproject TO myprojectuser;

• When you are finished, exit out of the PostgreSQL prompt by typing:

postgres=# \q

#Step 3 — Creating a Python Virtual Environment for your Project

• thin the project directory, create a Python virtual environment by typing:

mkdir ~/myprojectdir
cd ~/myprojectdir

• Within the project directory, create a Python virtual environment by typing:

python3 -m venv myprojectenv

• Before installing your project’s Python requirements, you will need to activate the virtual environment. You can do that by typing:

source myprojectenv/bin/activate

• With your virtual environment active, install Django, Gunicorn, and the psycopg2 PostgreSQL adaptor with the local instance of pip

(myprojectenv)$ pip install django gunicorn psycopg2-binary

#Step 4 — Creating and Configuring a New Django Project

• With your Python components installed, you can now create the actual Django project files.

(myprojectenv)$ django-admin startproject myproject ~/myprojectdir

• The first thing you should do with your newly created project files is adjust the settings. Open the settings file in your text editor:

(myprojectenv)$ nano ~/myprojectdir/myproject/settings.py

• Start by locating the ALLOWED_HOSTS directive.

# ~/myprojectdir/myproject/settings.py
ALLOWED_HOSTS = ['your_server_domain_or_IP', 'second_domain_or_IP', . . ., 'localhost']

• Next, find the section that configures database access. It will start with DATABASES. The configuration in the file is for a SQLite database.

. . .
DATABASES = {
    'default': {
        'ENGINE': 'django.db.backends.postgresql_psycopg2',
        'NAME': 'myproject',
        'USER': 'myprojectuser',
        'PASSWORD': 'password',
        'HOST': 'localhost',
        'PORT': '',
    }
}
. . .

• Next, move down to the bottom of the file and add a setting indicating where the static files should be placed.

. . .
STATIC_URL = 'static/'

# Default primary key field type
# https://docs.djangoproject.com/en/4.0/ref/settings/#default-auto-field

DEFAULT_AUTO_FIELD = 'django.db.models.BigAutoField'

import os
STATIC_ROOT = os.path.join(BASE_DIR, 'static/')

#Step 5 — Completing Initial Project Setup

• Now, you can migrate the initial database schema to our PostgreSQL database using the management script:

(myprojectenv)$ ~/myprojectdir/manage.py makemigrations
(myprojectenv)$ ~/myprojectdir/manage.py migrate

• Create an administrative user for the project by typing:

(myprojectenv)$ ~/myprojectdir/manage.py createsuperuser

• You can collect all of the static content into the directory location that you configured by typing:

(myprojectenv)$ ~/myprojectdir/manage.py collectstatic

#Step 6 — Testing Gunicorn’s Ability to Serve the Project

(myprojectenv)$ cd ~/myprojectdir
(myprojectenv)$ gunicorn --bind 0.0.0.0:8000 myproject.wsgi

• You’re now finished configuring your Django application. You can back out of our virtual environment by typing:

(myprojectenv)$ deactivate

#Step 7 — Creating systemd Socket and Service Files for Gunicorn You have tested tha

sudo nano /etc/systemd/system/gunicorn.socket

• Inside, you will create a [Unit] section to describe the socket, a [Socket] section to define the socket location, and an [Install] section to make sure the socket is created at the right time:

[Unit]
Description=gunicorn socket

[Socket]
ListenStream=/run/gunicorn.sock

[Install]
WantedBy=sockets.target

• Save and close the file when you are finished.
• Next, create and open a systemd service file for Gunicorn with sudo privileges in your text editor. The service filename should match the socket filename with the exception of the extension:

sudo nano /etc/systemd/system/gunicorn.service

[Unit]
Description=gunicorn daemon
Requires=gunicorn.socket
After=network.target

[Service]
User=sammy
Group=www-data
WorkingDirectory=/home/sammy/myprojectdir
ExecStart=/home/sammy/myprojectdir/myprojectenv/bin/gunicorn \
          --access-logfile - \
          --workers 3 \
          --bind unix:/run/gunicorn.sock \
          myproject.wsgi:application

[Install]
WantedBy=multi-user.target

• You can now start and enable the Gunicorn socket. This will create the socket file at /run/gunicorn.sock now and at boot. When a connection is made to that socket, systemd will automatically start the gunicorn.service to handle it

sudo systemctl start gunicorn.socket
sudo systemctl enable gunicorn.socket

#Step 8 — Checking for the Gunicorn Socket File

• Check the status of the process to find out whether it was able to start:

sudo systemctl status gunicorn.socket

• Next, check for the existence of the gunicorn.sock file within the /run directory:

file /run/gunicorn.sock

#Step 9 — Testing Socket Activation

sudo systemctl status gunicorn

• To test the socket activation mechanism, you can send a connection to the socket through curl by typing:

curl --unix-socket /run/gunicorn.sock localhost

• You should receive the HTML output from your application in the terminal. This indicates that Gunicorn was started and was able to serve your Django application. You can verify that the Gunicorn service is running by typing:

sudo systemctl status gunicorn

• Check your /etc/systemd/system/gunicorn.service file for problems. If you make changes to the /etc/systemd/system/gunicorn.service file, reload the daemon to reread the service definition and restart the Gunicorn process by typing

sudo systemctl daemon-reload
sudo systemctl restart gunicorn

#Step 10 — Configure Nginx to Proxy Pass to Gunicorn

• Start by creating and opening a new server block in Nginx’s sites-available directory:

sudo nano /etc/nginx/sites-available/myproject

server {
    listen 80;
    server_name server_domain_or_IP;

    location = /favicon.ico { access_log off; log_not_found off; }
    location /static/ {
        alias /home/sammy/myprojectdir/staticfiles/;
    }

    location /media {
        autoindex on;
        alias /home/sammy/myprojectdir/media/;
    }

    location / {
        include proxy_params;
        proxy_pass http://unix:/run/gunicorn.sock;
    }
}

• Save and close the file when you are finished. Now, you can enable the file by linking it to the sites-enabled directory:

sudo ln -s /etc/nginx/sites-available/myproject /etc/nginx/sites-enabled

• Test your Nginx configuration for syntax errors by typing:

sudo nginx -t

• If no errors are reported, go ahead and restart Nginx by typing:

sudo systemctl restart nginx

• you need to open up your firewall to normal traffic on port 80

sudo ufw allow 'Nginx Full'

You should now be able to go to your server’s domain or IP address to view your application.

#Step 11 — Troubleshooting Nginx and Gunicorn

• Nginx Is Showing the Default Page Instead of the Django Application

sudo tail -F /var/log/nginx/error.log

• Django Is Displaying: “could not connect to server: Connection refused”

sudo systemctl status postgresql

• If it is not, you can start it and enable it to start automatically at boot (if it is not already configured to do so) by typing:

sudo systemctl start postgresql
sudo systemctl enable postgresql

If you change Gunicorn socket or service files, reload the daemon and restart the process by typing:

sudo systemctl daemon-reload
sudo systemctl restart gunicorn.socket gunicorn.service

If you change the Nginx server block configuration, test the configuration and then Nginx by typing:

sudo nginx -t && sudo systemctl restart nginx