[Django] Cheat Sheet #python #django

django_cheat_sheet.py

# *****************************************************************************
# CODING STYLE > MAKING YOUR CODE READABLE
# *****************************************************************************


# 1. Avoid abbreviating variable names.
# 2. Write out your function argument names.
# 3. Document your classes and methods.
# 4. Comment your code.
# 5. Refactor repeated lines of code into reusable functions or methods.
# 6. Keep functions and methods short. A good rule of thumb is that scrolling
# should not be necessary to read an entire function or method.

# TIP: Use Flake8 for Checking Code Quality.


# *****************************************************************************
# CODING STYLE > THE WORD ON IMPORTS
# *****************************************************************************


# Imports should be grouped in the following order:

# 1. Standard library imports.
# 2. Core Django imports.
# 3. Third-party app imports.
# 4. Imports from your apps.

# Use explicit relative imports.
# Avoid using import *


# *****************************************************************************
# CODING STYLE > OTHERS
# *****************************************************************************


# Use underscores in URL pattern names rather than dashes.


# *****************************************************************************
# DJANGO-ADMIN
# *****************************************************************************


django-admin check                       # Checks the entire django project for potential problems
django-admin changepassword <username>   # Allows changing a user’s password. It prompts you to enter a new password twice for the given user.
django-admin clearsessions               # Can be run as a cron job or directly to clean out expired sessions.
django-admin collectstatic               # Helps to collect all the static files in the one mentioned director
django-admin createsuperuser             # Creates a superuser account (a user who has all permissions).
django-admin compilemessages             # Compiles .po files to .mo files for use with builtin gettext support
django-admin createcachetable            # Creates the tables needed to use the SQL cache backend.
django-admin dbshell                     # Runs the command-line client for specified database, or the default database if none is provided.
django-admin diffsettings                # Displays differences between the current settings.py and Django's default settings.
django-admin dumpdata                    # Output the contents of the database as a fixture of the given format (using each model's default manager unless --all is specified).
django-admin flush                       # Removes ALL DATA from the database, including data added during migrations. Does not achieve a "fresh install" state.
django-admin inspectdb                   # Introspects the database tables in the given database and outputs a Django model module.
django-admin loaddata                    # Installs the named fixture(s) in the database.
django-admin makemessages                # Runs over the entire source tree of the current directory and pulls out all strings marked for translation. It creates (or updates) a message file in the conf/locale (in the django tree) or locale (for projects and applications) directory. You must run this command with one of either the --locale, --exclude, or --all options.
django-admin help                        # display usage information and a list of the commands provided by each application
django-admin makemigrations              # create new migrations to the database based on the changes detected in the models
django-admin migrate                     # synchronize the database state with your current state project models and migrations
django-admin remove_stale_contenttypes   # Deletes stale content types (from deleted models) in your database.y.
django-admin runserver                   # start the development webserver at 127.0.0.1 with the port 8000
django-admin sendtestemail               # Sends a test email to the email addresses specified as arguments.
django-admin shell                       # Runs a Python interactive interpreter. Tries to use IPython or bpython, if one of them is available. Any standard input is executed as code.
django-admin showmigrations              # Shows all available migrations for the current project.
django-admin sqlflush                    # Returns a list of the SQL statements required to return all tables in the database to the state they were in just after they were installed.
django-admin sqlmigrate                  # Prints the SQL statements for the named migration.
django-admin sqlsequencereset            # Prints the SQL statements for resetting sequences for the given app name(s).
django-admin squashmigrations            # Squashes an existing set of migrations (from first until specified) into a single new one.
django-admin startapp <Appname>          # create a new django application with the specified name
django-admin startproject <ProjectName>  # create a new project directory structure
django-admin testserver                  # Runs a development server with data from the given fixture(s).
django-admin version                     # display the current django version

django_deployment.md

Django Deployment to Ubuntu 18.04

In this guide I will go through all the steps to create a VPS, secure it and deploy a Django application. This is a summarized document from this digital ocean doc

Any commands with "$" at the beginning run on your local machine and any "#" run when logged into the server

Create A Digital Ocean Droplet

Use this link and get $10 free. Just select the $5 plan unless this a production app.

Security & Access

Creating SSH keys (Optional)

You can choose to create SSH keys to login if you want. If not, you will get the password sent to your email to login via SSH

To generate a key on your local machine

$ ssh-keygen

Hit enter all the way through and it will create a public and private key at

~/.ssh/id_rsa
~/.ssh/id_rsa.pub

You want to copy the public key (.pub file)

$ cat ~/.ssh/id_rsa.pub

Copy the entire output and add as an SSH key for Digital Ocean

Login To Your Server

If you setup SSH keys correctly the command below will let you right in. If you did not use SSH keys, it will ask for a password. This is the one that was mailed to you

$ ssh root@YOUR_SERVER_IP

Create a new user

It will ask for a password, use something secure. You can just hit enter through all the fields. I used the user "djangoadmin" but you can use anything

# adduser djangoadmin

Give root privileges

# usermod -aG sudo djangoadmin

SSH keys for the new user

Now we need to setup SSH keys for the new user. You will need to get them from your local machine

Exit the server

You need to copy the key from your local machine so either exit or open a new terminal

# exit

You can generate a different key if you want but we will use the same one so lets output it, select it and copy it

$ cat ~/.ssh/id_rsa.pub

Log back into the server

$ ssh root@YOUR_SERVER_IP

Add SSH key for new user

Navigate to the new users home folder and create a file at '.ssh/authorized_keys' and paste in the key

# cd /home/djangoadmin
# mkdir .ssh
# cd .ssh
# nano authorized_keys
Paste the key and hit "ctrl-x", hit "y" to save and "enter" to exit

Login as new user

You should now get let in as the new user

$ ssh djangoadmin@YOUR_SERVER_IP

Disable root login

# sudo nano /etc/ssh/sshd_config

Change the following

PermitRootLogin no
PasswordAuthentication no

Reload sshd service

# sudo systemctl reload sshd

Simple Firewall Setup

See which apps are registered with the firewall

# sudo ufw app list

Allow OpenSSH

### sudo ufw allow OpenSSH

Enable firewall

# sudo ufw enable

To check status

# sudo ufw status

We are now done with access and security and will move on to installing software

Software

Update packages

# sudo apt update
# sudo apt upgrade

Install Python 3, Postgres & NGINX

# sudo apt install python3-pip python3-dev libpq-dev postgresql postgresql-contrib nginx curl

Postgres Database & User Setup

# sudo -u postgres psql

You should now be logged into the pg shell

Create a database

CREATE DATABASE btre_prod;

Create user

CREATE USER dbadmin WITH PASSWORD 'abc123!';

Set default encoding, tansaction isolation scheme (Recommended from Django)

ALTER ROLE dbadmin SET client_encoding TO 'utf8';
ALTER ROLE dbadmin SET default_transaction_isolation TO 'read committed';
ALTER ROLE dbadmin SET timezone TO 'UTC';

Give User access to database

GRANT ALL PRIVILEGES ON DATABASE btre_prod TO dbadmin;

Quit out of Postgres

\q

Vitrual Environment

You need to install the python3-venv package

# sudo apt install python3-venv

Create project directory

# mkdir pyapps
# cd pyapps

Create venv

# python3 -m venv ./venv

Activate the environment

# source venv/bin/activate

Git & Upload

Pip dependencies

From your local machine, create a requirements.txt with your app dependencies. Make sure you push this to your repo

$ pip freeze > requirements.txt

Create a new repo and push to it (you guys know how to do that)

Clone the project into the app folder on your server (Either HTTPS or setup SSH keys)

# git clone https://github.com/yourgithubname/btre_project.git

Install pip modules from requirements

You could manually install each one as well

# pip install -r requirements.txt

Local Settings Setup

Add code to your settings.py file and push to server

try:
    from .local_settings import *
except ImportError:
    pass

Create a file called local_settings.py on your server along side of settings.py and add the following

• SECRET_KEY
• ALLOWED_HOSTS
• DATABASES
• DEBUG
• EMAIL_*

Run Migrations

# python manage.py makemigrations
# python manage.py migrate

Create super user

# python manage.py createsuperuser

Create static files

python manage.py collectstatic

Create exception for port 8000

# sudo ufw allow 8000

Run Server

# python manage.py runserver 0.0.0.0:8000

Test the site at YOUR_SERVER_IP:8000

Add some data in the admin area

Gunicorn Setup

Install gunicorn

# pip install gunicorn

Add to requirements.txt

# pip freeze > requirements.txt

Test Gunicorn serve

# gunicorn --bind 0.0.0.0:8000 btre.wsgi

Your images, etc will be gone

Stop server & deactivate virtual env

ctrl-c
# deactivate

Open gunicorn.socket file

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

Copy this code, paste it in and save

[Unit]
Description=gunicorn socket

[Socket]
ListenStream=/run/gunicorn.sock

[Install]
WantedBy=sockets.target

Open gunicorn.service file

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

Copy this code, paste it in and save

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

[Service]
User=djangoadmin
Group=www-data
WorkingDirectory=/home/djangoadmin/pyapps/btre_project
ExecStart=/home/djangoadmin/pyapps/venv/bin/gunicorn \
          --access-logfile - \
          --workers 3 \
          --bind unix:/run/gunicorn.sock \
          btre.wsgi:application

[Install]
WantedBy=multi-user.target

Start and enable Gunicorn socket

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

Check status of guinicorn

# sudo systemctl status gunicorn.socket

Check the existence of gunicorn.sock

# file /run/gunicorn.sock

NGINX Setup

Create project folder

# sudo nano /etc/nginx/sites-available/btre_project

Copy this code and paste into the file

server {
    listen 80;
    server_name YOUR_IP_ADDRESS;

    location = /favicon.ico { access_log off; log_not_found off; }
    location /static/ {
        root /home/djangoadmin/pyapps/btre_project;
    }
    
    location /media/ {
        root /home/djangoadmin/pyapps/btre_project;    
    }

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

Enable the file by linking to the sites-enabled dir

# sudo ln -s /etc/nginx/sites-available/btre_project /etc/nginx/sites-enabled

Test NGINX config

# sudo nginx -t

Restart NGINX

# sudo systemctl restart nginx

Remove port 8000 from firewall and open up our firewall to allow normal traffic on port 80

# sudo ufw delete allow 8000
# sudo ufw allow 'Nginx Full'

You will probably need to up the max upload size to be able to create listings with images

Open up the nginx conf file

# sudo nano /etc/nginx/nginx.conf

Add this to the http{} area

client_max_body_size 20M;

Reload NGINX

# sudo systemctl restart nginx

Media File Issue

You may have some issues with images not showing up. I would suggest, deleting all data and starting fresh as well as removeing the "photos" folder in the "media folder"

# sudo rm -rf media/photos

Domain Setup

Go to your domain registrar and create the following a record

@  A Record  YOUR_IP_ADDRESS
www  CNAME  example.com

Go to local_settings.py on the server and change "ALLOWED_HOSTS" to include the domain

ALLOWED_HOSTS = ['IP_ADDRESS', 'example.com', 'www.example.com']

Edit /etc/nginx/sites-available/btre_project

server {
    listen: 80;
    server_name xxx.xxx.xxx.xxx example.com www.example.com;
}

Reload NGINX & Gunicorn

# sudo systemctl restart nginx
# sudo systemctl restart gunicorn