Developing

web Projects

 with

Fabric

By Tianyi

Full Stack Web Developer

• Front end (JavaScript, HTML, CSS)
• Back end (Python, Ruby,  etc.)
• Data Modeling (Postgresql, Mysql, NoSQL, etc.)
  
• Devops (Nginx, uWSGI, Crontabs, Networking, Monitoring. etc.)
• We even talk to the business people. 
• A lot more...
  

YEAH! We're cool!

The processes of a web project

• Set up the project
• Develop the project
• Deploy the project
• Fix or add new features 
• Deploy the project again
  

Set up a Django project

• Install system packages (Postgresql, Mysql Git, SVN etc.)
• Install python tools (pip, virtualenv etc.)
• Create virtual environment
  
• Python packages (Django, South etc.)
• Set up databases
• More
  

Developing the application

• Write tests
• Write code
• Run tests
• Version control the code

Deploy the application

• Do all the tasks listed in start a Django project.
• Run tests, make sure no failing tests.
• Set up Nginx, uWSGI etc.
  

Boring parts

• Install system packages
  
• Install python tools
  
• Create virtual environment
  
• Python packages
• Set up database
• Run Syncdb, data migration or import data
• Run tests make sure nothing fails
• Set up uWSGI
• Set up Nginx
  

Fun Parts

• Write code
• Watch your application working
  

We Just Wanna Have Some Fun

Fabric

Fabric is a Python library and command-line tool for streamlining the use of SSH for application deployment or systems administration tasks

Fabric Tasks

from fabric.api import env, local, task, settings

env.hosts = ['123.123.1.1'] # Some remote hosts ip

@task
def install_postgres_locally():
    with settings(user='root'):
        local('apt-get install postgresql postgresql-client')

@task 
def install_postgres_remotely():
    with settings(user='root'):
        run('apt-get install postgresql postgresql-client') 

fab install_postgres_locally

fab install_postgres_remotely

fabtools

fabtools includes useful functions to help you write your Fabric files.

fabtools makes it easier to manage system users, packages, databases, etc.

from fabric.api import local, task, settings

from fabtools import deb, arch

@task 
install_postgres_deb():
    with settings(user='root'):
        deb.install('postgresql postgresql-client')


@task 
def install_postgres_arch():
    with settings(user='root')
        arch.install('postgresql postgresql-client')

Demo

Talk is cheap. Show me the code

                       -- Torvalds, Linus (2000-08-25)

Deploying a Django application

• uWSGI
• Nginx

Configuration files

Normal we can just have uWSGI, Nginx, Postgresql configuration  files ready, and use Fabric command to copy the files over.

put('/path/to/local/uwsgi.ini, '/path/to/remote/uwsgi.ini')  

We can go further than this :)


Jinja2

JJinja2 is a full featured template engine for Python. It has full unicode support, an optional integrated sandboxed execution environment, widely used and BSD licensed.

Jinja2

# the base directory (full path)
{% if chdir %}
chdir = {{ chdir }}
{% endif %}
# Django's wsgi file
{% if project_name %}
module = {{ project_name }}.wsgi
{% endif %}
{% if virtualenv_path %}
virtualenv = {{ virtualenv_path }}
{% endif %}
# process-related settings
master = true 
{% if processes %}
processes = {{ processes }}
{% else %}
processes = 4
{% endif %}
... 

Fabric Tasks

from fabric.api import env, task, settings, run, cd

from jinja2 import Environment, FileSystemLoader


@task
def create_uwsgi_conf():
    templateLoader = FileSystemLoader(searchpath="templates")
    template_env = Environment(loader=templateLoader)
    template = template_env.get_template('uwsgi.ini')

    uwsgi_params = {}
    uwsgi_params['chdir'] = env.project_path
    uwsgi_params['project_name'] = env.project_name
    uwsgi_params['virtualenv_path'] = env.virtualenv_path
    uwsgi_params['processes'] = 10
    uwsgi_params['socket_path'] = env.project_path
    with open('./uwsgi.ini', 'w') as output_file:
        output_file.write(template.render(uwsgi_params)) 

Demo

Hope this will work......

Problems with Fabric

But it's not all too bad

Questions ?

Please ask me something :)

Don't be afraid of embarrassing me :)

@3quarterstack

https://github.com/tianyi33