[Tutorial] How to Deploy a Python/Django app

[hades]

Tinand cont ca pe internet e plin de tutoriale de genu (o mare parte din ele nu prea sunt de actualitate) am zis sa scriu un mini-tutorial despre cum trebuie configurat si pregatit un server pentru deploy-ul unei aplicatii Django.

1. Pregatirea serverului & instalarea librariilor

sudo apt-get update
sudo apt-get upgrade
sudo apt-get install python-dev python virtualenv

2. Instalam nginx:

sudo apt--get install nginx

3. Install mysql:

sudo apt-get install mysql-server
sudo apt-get install libmysqlclient-dev
sudo apt-get install mysql-python

4. Creem un user nou; User ce-l vom folosi pentru deploy-ul propriuzis.

adduser example

5. Creem directorul proiectului; Virtualenv pentru el. Instalam requirements-urile proiectului

mkdir app
cd app; virtualenv venv
cd venv; source bin/activate

Acum ca avem virtualenv-ul activat, facem un pip install -r requirements.txt (asta depinde de unde se afla requirements-urile voastre.

6. Instalam gunicorn (un python wsgi http server de unix)

pip install gunicorn

Pentru a testa daca totul functioneaza cum trebuie pana aici:

gunicorn -b 0.0.0.0:8080 project.wsgi

7. Creem un mic bash script pentru gunicorn, ce va fi folosit de supervisor.

Bash scriptul o sa arate cam asa:

#!/bin/bash

NAME="app"                                         # Numele Aplicatiei
DJANGODIR=/home/example/app/project/               # Django project directory
SOCKFILE=/home/example/app/project/gunicorn.sock   # we will communicte using this unix socket
USER=example                                       # the user to run as
GROUP=www-data                                     # the group to run as
NUM_WORKERS=3                                      # how many worker processes should Gunicorn spawn
DJANGO_SETTINGS_MODULE=app.settings                # which settings file should Django use
DJANGO_WSGI_MODULE=app.wsgi                        # WSGI module name

echo "Starting $NAME as `whoami`"

# Activam virtualenv
cd $DJANGODIR
. ../venv/bin/activate
export DJANGO_SETTINGS_MODULE=$DJANGO_SETTINGS_MODULE
export PYTHONPATH=$DJANGODIR:$PYTHONPATH

RUNDIR=$(dirname $SOCKFILE)
test -d $RUNDIR || mkdir -p $RUNDIR

# Start gunicorn
../venv/bin/gunicorn ${DJANGO_WSGI_MODULE}:application \
  --name $NAME \
  --workers $NUM_WORKERS \
  --bind=unix:$SOCKFILE \
  --user="$USER" \
  --log-level=debug \
  --log-file=-

8. Scriem configul pentru supervisor:

[program:app]
command = /home/example/app/venv/gunicorn_script.sh
user = example
group = www-data
stdout_logfile = /home/example/app/project/logs/supervisor.log
redirect_stderr = true
enviroment=LANG=en_US.UTF-8,LC_ALL=en_US.UTF-8

Il pornim:

sudo supervisorctl start app

9. Ce mai ramane acum de facut e sa scriem configul de nginx in asa fel incat sa ne foloseasca drept proxy pentru servirea aplicatiei.

Un config foarte basic de nginx arata cam asa:

upstream app_server {
  # fail_timeout=0 means we always retry an upstream even if it failed
  # to return a good HTTP response (in case the Unicorn master nukes a
  # single worker for timing out).

  server unix:/home/example/app/project/gunicorn.sock fail_timeout=0;
}

server {

    listen   80;
    server_name example.com;

    client_max_body_size 4G;

    access_log /home/example/app/project/logs/nginx-access.log;
    error_log /home/example/app/project/logs/nginx-error.log;


    location / {
        # an HTTP header important enough to have its own Wikipedia entry:
        #   http://en.wikipedia.org/wiki/X-Forwarded-For
        proxy_set_header X-Forwarded-For $proxy_add_x_forwarded_for;

        # enable this if and only if you use HTTPS, this helps Rack
        # set the proper protocol for doing redirects:
        # proxy_set_header X-Forwarded-Proto https;

        # pass the Host: header from the client right along so redirects
        # can be set properly within the Rack application
        proxy_set_header Host $http_host;

        # we don't want nginx trying to do something clever with
        # redirects, we set the Host: header above already.
        proxy_redirect off;

        # set "proxy_buffering off" *only* for Rainbows! when doing
        # Comet/long-poll stuff.  It's also safe to set if you're
        # using only serving fast clients with Unicorn + nginx.
        # Otherwise you _want_ nginx to buffer responses to slow
        # clients, really.
        # proxy_buffering off;

        # Try to serve static files from nginx, no point in making an
        # *application* server like Unicorn/Rainbows! serve static files.
        if (!-f $request_filename) {
            proxy_pass http://example_app_server;
            break;
        }
    }
}

In linii mari (nu chiar mari, ca am cuprins toti pasii importanti) asa ar arata pregatirea unui server pentru un deploy Django/Python. Ramane de vazut acum cum va jucati cu permisiile. De-asemenea mai mult ca singur o sa vreti sa faceti niste forward la headere din configul de nginx.