hendrix: A Python repository from anthonyalmarza

#Hendrix Twisted meets Django: Making deployment easy

##Overview

Hendrix is a multi-threaded, multi-process and asynchronous web server for Django projects. The idea here is to have a highly extensible wsgi deployment tool that is fast, transparent and easy to use.

###Features

Multi-processing - The WSGI app can be served from multiple processes on a single machine. Meaning that it can leverage multicore servers.
Optional Resource Caching - Process distributed resource caching, dynamically serving gzipped files. It's also possible to extend the current caching functionality by subclassing the hendrix CacheService and adding a reference to that subclass within a HENDRIX_SERVICES tuple of tuples e.g. (('name', 'app.MyCustomCache'),) in your Django settings file. Just use the --cache flag to turn caching on.
Built-in SSL Support - SSL is also process distributed, just provide the options --key /path/to/private.key and --cert /path/to/signed.cert to enable SSL and process distributed TLS
Multi-threading from within Django - Enables the use of Twisted's defer module and deferToThread and callInThread methods from within Django
Built-in Websockets Framework
Daemonize by passing the -d or --daemonize flags to hx

###Installation

Using pip

pip install hendrix

###Running the Development Server

cd to the directory where your manage.py file is located and...

hx start --dev

This is roughly the equivalent of running the django devserver.

see the examples below for more configuration options.

-- ###Deployment

#####Ubuntu Servers If you're running an Ubuntu/Debian server you may want to install Hendrix as a service. To do this you can use the helper script install-hendrix-service. Here's how you do it:

You'll need to use virtualenv. If you don't have that set up, follow the virtualenv instructions here.
Paste the example below into a file called hendrix.conf

Enter the following:

sudo install-hendrix-service hendrix.conf

Now you have hendrix running as a service on your server. Easy. Use the service as you would any other service i.e. sudo service hendrix start.

#####Here is an example hendrix.conf. It is in Yaml format.

# path to virtualenv
virtualenv: /home/anthony/venvs/hendrix

#path to manage.py
project_path: /home/anthony/django/myproject

#### everything below is optional #####
# settings, if you use different ones for production
settings: 'dot.path.to.settings'

# default 1
processes: 1

# default 8000
http_port: 8000

# default false
cache: false

# default 8080
cache_port: 8888

# default 4430
https_port: 4430

# key and cacert are both required if you want to run ssl
key: /path/to/my/priv.key

##Examples The following outlines how to use Hendrix in your day to day life/development.

#####For help and a complete list of the options:

hx -h

hx --help

#####Starting a server with 4 processes (1 parent and 3 child processes):

hx start -w 3

#####Stopping that server:

hx stop

** Note that stopping a server is dependent on the settings file and http_port used. **

E.g. Running a server on port 8000 with local_settings.py would yield 8000_local_settings.pid which would be used to kill the server. I.e. if you start with hx start --settings local_settings then stop by hx stop --settings local_settings

#####Restarting a server:

hx restart

##Features in more depth

###Serving Static Files Serving static files via Hendrix is optional but easy.

a default static file handler is built into Hendrix which can be used by adding the following to your settings:

HENDRIX_CHILD_RESOURCES = (
    'hendrix.contrib.resources.static.DefaultDjangoStaticResource',

    # uncomment if you would like to serve the django admin static files
    #'hendrix.contrib.resources.static.DjangoAdminStaticResource',
)

No other configuration is necessary. You don't need to add anything to urls.py.

You can also easily create your own custom static or other handlers by adding them to HENDRIX_CHILD_RESOURCES.

###SSL This is made possible by creating a self-signed key. First make sure you have the newest patched version of openssl. Then generate a private key file:

openssl genrsa > key.pem

Then generate a self-signed SSL certificate:

openssl req -new -x509 -key key.pem -out cacert.pem -days 1000

Finally you can run single SSL server by running:

hx start --dev --key key.pem --cert cacert.pem

or a process distributed set of SSL servers:

hx start --dev --key key.pem --cert cacert.pem -w 3

Just go to https://[insert hostname]:4430/ to check it out. N.B. Your browser will warn you not to trust the site... You can also specify which port you want to use by passing the desired number to the --https_port option

###Caching

At the moment a caching server is deployed by default on port 8000. Is serves gzipped content, which is pretty cool - right?

#####How it works

The Hendrix cache server is a reverse proxy that sits in front your Django app. However, if you wanted to switch away from the cache server you can always point to the http port (default 8080).

It works by forwarding requests to the http server running the app and caches the response depending on the availability of max-age [seconds] in a Cache-Control header.

#####Busting the cache

Note that you can bust the cache (meaning force it not to cache) by passing a query in your GET request e.g. http://somesite.com/my/resource?somevar=test. You can also force the query to cache by specifying cache=true in the query e.g. http://somesite.com/my/resource?somevar=test,cache=true (so long as a max-age is specified for the handling view). What this means is that you can let the browser do some or none of the js/css caching if you so want.

#####Caching in Django

In your project view modules use the cache_control decorator to add a max-age of your choosing. e.g.

from django.views.decorators.cache import cache_control

@cache_control(max_age=60*60*24)  # cache it for a day
def homePageView(request):
    ...

and that's it! Hendrix will do the rest. Django docs examples here

#####Turning cache off

You can turn caching on by passing the flags -c or --cache. You can also change which port you want to use with the --cache_port option.

#####Global Vs Local

If you're running multiple process using the -w or --workers options caching will be process distributed by default. Meaning there will be a reverse proxy cache server for each process. However if you want to run the reverse proxy server on a single process just use the -g or --global_cache flags.

... here "local" means local to the process.

###Testing

In your virtualenv first run the following:

pip install -r requirements
pip install -r test-requirements

Tests live in hendrix.test and are most easily run using Twisted's trial test framework.

/home/jsmith:~$ trial hendrix
hendrix.test.test_deploy
  DeployTests
    test_multiprocessing ...                                               [OK]
    test_options_structure ...                                             [OK]
    test_settings_doesnt_break ...                                         [OK]

-------------------------------------------------------------------------------
Ran 3 tests in 0.049s

PASSED (successes=3)

trial will find your tests so long as you name the package/module such that it starts with "test" e.g. hendrix/contrib/cache/test/test_services.py.

Note that the module needs to have a subclass of unittest.TestCase via the expected unittest pattern. For more info on trial go here.

N.B. that in the hendrix.test __init__.py file a subclass of TestCase called HendrixTestCase has been created to help tests various use cases of hendrix.deploy.HendrixDeploy

###Contributions Contributions are more than welcome. Feedback and bug reports especially.

Unfortunately a majority of the codebase is not covered by tests. This means that if you want to make changes to Hendrix you'll need to click around to see if it works. We're working hard to change this so please bare with us until then.

###Twisted Twisted is what makes this all possible. Mostly. Check it out here.

###Yet to come

Ensure stability of current implementation of web sockets
Load Balancing
Twisted logging
Cache regex logic/config file
Ansible deployment utility
Salt deployment utility
more tests...

###History It started as a fork of the slashRoot deployment module.

The name is the result of some inane psychological formula wherein the 'twisted' version of Django Reinhardt is Jimi Hendrix.

Hendrix is currently maintained by Reelio.

anthonyalmarza/hendrix