Example Fabric fabfile.py. It's a hodgepodge of old scripts and probably isn't best practice (uWSGI ought to have an init script), but it should give you a practical idea of how to use Fabric. This fabfile relies heavily on custom settings from a Django project in order to be more DRY. Includes commands for setting up a fresh Ubuntu Server insta…

fabfile.py

# -*- coding: utf-8 -*-
#Copyright (C) 2013 Seán Hayes

import my_project.settings as dj_settings
from fabric.api import local, run, sudo, env, prompt, settings, cd, parallel, execute
from fabric.contrib.files import exists
from fabric.decorators import hosts, roles, runs_once
import json
import logging
import os

logging.getLogger('').setLevel(logging.INFO)
logger = logging.getLogger(__name__)

env.forward_agent = True

env.user = 'username'

role_list = (
	'web',
	'cache',
	'db',
	'celery',
)

host_dict = {
	'100.100.100.100': ('web', 'cache',),
	'100.100.100.101': ('db', 'celery',),
}

env.hosts = host_dict.keys()

for r in role_list:
	env.roledefs[r] = []

for k_host, v_roles in host_dict.items():
	for v_role in v_roles:
		env.roledefs[v_role].append(k_host)

env.code_dir = '/srv/'

env.package_name = dj_settings.PACKAGE_MODULE
env.project_dir = '%s%s/' % (env.code_dir, dj_settings.PROJECT_NAME,)
env.package_dir = '%s%s/' % (env.project_dir, dj_settings.PACKAGE_MODULE,)
env.project_git_uri = '[email protected]:some-user/my-project.git'
env.config_dir = '%sconfig/generated/' % env.project_dir
env.log_dir = '%slogs/' % env.project_dir

env.pip_dir = '%spip/' % env.code_dir

env.celery_script_dir = '%scelery/init.d/' % env.config_dir

main_dirs = [
	env.pip_dir,
]

project_dirs = [
	env.log_dir,
]

apt_packages = [
	'debconf-utils',
	'git',
	'mercurial',
	'subversion',
	'ntp',
	'gdebi-core',
	'graphviz',
	'graphviz-dev',
	'libmemcached-tools',
	'memcached',
	'nginx',
	'pkg-config',
	'postfix',
	'python-pip',
	'python-virtualenv',
	'python-all-dev',
	'postgresql',
	#'rabbitmq-server',
	#TODO: try to get as many of these as possible in requirements.txt
	#'python-django-doc',
	#some require 1/4 GB of dependencies to build the PIP version, which is unacceptable for this kind of application
	'python-imaging',
	'python-psycopg2',
	#'python-exactimage',
	#'python-crypto',
]

#Run the following to make binary eggs when setuptools isn't used
#python -c "import setuptools; execfile('setup.py')" bdist_egg

# tasks

def create_user():
	"Create admin user on fresh cloud instance."
	username = prompt('Enter username to create: ', default=env.user)
	with settings(user='root'):
		run('useradd --groups sudo,www-data -d /home/%s -m %s' % (username, username))
		run('passwd %s' % username)

def switch_to_bash():
	"switch from dash (the Ubuntu default) to bash"
	with cd('/bin'):
		#has to be one command since each call to sudo() is a different session,
		#and you can't login if sh isn't set
		sudo('rm sh; ln -s bash sh')

@roles('db')
@runs_once
def setup_pgsql():
	"Sets up PostgreSQL user and databases."
	name = prompt('Enter PostgreSQL role/db to create: ', default=env.project_name)
	sudo('createuser -s -P %s' % name, user='postgres')
	sudo('createdb -O %s %s' % (name, name), user='postgres')

def mkdirs(dirs):
	"Sets up the directories we need and sets the right permissions."
	for d in dirs:
		if not exists(d):
			sudo('mkdir %s' % d)
			sudo('chown %s:www-data %s' % (env.user, d))
			sudo('chmod 775 %s' % d)

def upgrade_ubuntu():
	"Probably shouldn't run this through Fabric, but here's the commands for it anyway."
	sudo('apt-get install update-manager-core')
	#edit /etc/update-manager/release-upgrades, set Prompt=normal
	sudo('do-release-upgrade')

@parallel
def install_apt():
	"Updates package list, upgrades all packages to latest available version, and installs Apt dependencies for this project."
	sudo('apt-get update')
	sudo('apt-get upgrade')
	sudo('apt-get install -f %s' % ' '.join(apt_packages))

@parallel
def set_permissions():
	sudo('chown :www-data %s' % (env.code_dir,))
	sudo('chmod 775 %s' % env.code_dir)

@parallel
def install_pip():
	"Installs the PIP requirements for this project."
	with cd(env.pip_dir):
		sudo('pip install -r %srequirements.txt' % env.project_dir)

@parallel
def install_project():
	"Clones this project's Git repo if there's no copy on the target machine, else it pulls the latest version."
	if exists(env.project_dir):
		with cd(env.project_dir):
			run('git pull origin master')
	else:
		with cd(env.code_dir):
			run('git clone %s' % env.project_git_uri)
		sudo('chown -R %s:www-data %s' % (env.user, env.project_dir))
		sudo('chmod 775 %s' % env.project_dir)
			
		mkdirs(project_dirs)

@hosts('')
def install():
	"Runs the commands to create all necessary directories, install Apt and PIP dependencies, and install project files."
	execute(mkdirs, main_dirs)
	execute(install_apt)
	execute(set_permissions)
	execute(install_project)
	execute(install_pip)

@roles('db')
@runs_once
def migrate():
	with cd(env.package_dir):
		run('./manage.py syncdb --migrate')

@roles('web')
def collectstatic():
	with cd(env.project_dir):
		run('./manage.py collectstatic -l')

def refresh_config_files():
	"Regenerates dynamic config files using django-config-gen."
	with cd(env.package_dir):
		run('./manage.py config_gen')

def link_config_file(source, destination):
	with settings(warn_only=True):
		sudo('rm %s' % destination)
	sudo('ln -s %s %s' % (source, destination))

@roles('web')
def config_nginx():
	with settings(warn_only=True):
		sudo('rm /etc/nginx/sites-available/*')
	link_config_file(os.path.join(env.config_dir, 'nginx'), '/etc/nginx/sites-available/default')

@roles('db')
def config_postgresql():
	link_config_file(os.path.join(env.config_dir, 'pg_hba.conf'), '/etc/postgresql/9.1/main/pg_hba.conf')

@roles('cache')
def config_memcached():
	link_config_file(os.path.join(env.config_dir, 'memcached.conf'), '/etc/memcached.conf')

@roles('celery')
def config_celery():
	"Links Celery's Debian init scripts to /etc/init.d/."
	init_list=run('ls %s' % env.celery_script_dir).split()
	
	for script in init_list:
		p = '/etc/init.d/%s' % script
		init_file = os.path.join(env.celery_script_dir, script)
		link_config_file(init_file, p)
		sudo('chmod +x %s' % init_file)
	
	link_config_file(os.path.join(env.config_dir, 'celery/celeryd_default'), '/etc/default/celeryd')

def config_tzdata():
	"Configures the time zone for the server."
	run('echo \'America/New_York\'| sudo tee /etc/timezone')
	sudo('dpkg-reconfigure -f noninteractive tzdata')

@hosts('')
def config():
	"Runs the commands to generate config files using django-config-gen and symlinks the generated files to the normal config file locations for Apache, Nginx, Memcached, etc."
	execute(refresh_config_files)
	execute(config_nginx)
	execute(config_memcached)
	execute(config_celery)
	execute(config_tzdata)

@roles('web')
def reload_nginx():
	sudo('/etc/init.d/nginx reload')

@roles('web')
def reload_uwsgi():
	sudo('kill -HUP `cat %suwsgi.pid`' % env.project_dir)

@roles('celery')
def restart_celery():
	sudo('/etc/init.d/celeryd restart')
	sudo('/etc/init.d/celerybeat restart')
	sudo('/etc/init.d/celeryevcam restart')

@roles('cache')
def restart_memcached():
	sudo('/etc/init.d/memcached restart')

@hosts('')
def reload_servers():
	"Reloads Apache, Nginx, Rabbit MQ, and Celery where possible, otherwise it restarts them. Reloading config files is faster than restarting the processes."
	execute(reload_nginx)
	execute(reload_uwsgi)
	#sudo('/etc/init.d/rabbitmq-server reload')
	execute(restart_celery)
	execute(restart_memcached)

#local development scripts
def setup_git_shortcuts():
	#https://git.wiki.kernel.org/index.php/Aliases
	shortcuts = {
		'st': 'status',
	}
	for shortcut in shortcuts.items():
		local('git config --global alias.%s %s' % shortcut)

def set_django_colors():
	local('export DJANGO_COLORS="%s"' % dj_settings.DJANGO_COLORS)

def check_for_pdb():
	"Easily check for instances of pdb.set_trace() in your code before committing."
	local('find . -name \'*.py\'|xargs grep \'pdb.set_trace\'')
	#TODO: handle exit code

default_dump_file_template = '%s-dump.sql'
def dump_db():
	name = prompt('Enter PostgreSQL db to dump: ', default=env.project_name)
	local('sudo -u postgres pg_dump %s > %s' % (name, default_dump_file_template % name))

def load_db_dump():
	name = prompt('Enter PostgreSQL db to load: ', default=env.project_name)
	local('sudo -u postgres psql %s < %s' % (name, default_dump_file_template % name))

settings.py

#Python imports
import os
import sys

#Django imports
import django.conf.global_settings as DEFAULT_SETTINGS
from django.utils import timezone

PACKAGE_ROOT = os.path.abspath(os.path.dirname(__file__))

PROJECT_ROOT = PACKAGE_PARENT_DIR = os.path.dirname(PACKAGE_ROOT)
PROJECT_NAME = PROJECT_ROOT.split(os.sep)[-1]

PACKAGE_MODULE = __name__[:__name__.rfind('.')] if '.' in __name__ else PACKAGE_ROOT.split(os.sep)[-1]

LOG_DIR = os.path.join(PROJECT_ROOT, 'logs')

_colors_dict = {
	'error': ['red', 'bold'],
	'notice': ['red'],
	'http_info': ['cyan'],
	'http_success': ['blue'],
	'http_not_modified': ['cyan'],
	'http_redirect': ['cyan'],
	'http_not_found': ['red'],
	'http_bad_request': ['red'],
	'http_server_error': ['red'],
}
#needs to be exported as an environment variable
DJANGO_COLORS = ''.join([''.join([k, '=', ','.join(_colors_dict[k]), ';']) for k in _colors_dict])