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Fun with OpenShift

February 3rd, 2012 • 1 Comment

I’ve been playing around with OpenShift for the past hour. More specifically OpenShift Express which allows you to quickly develop apps Java, Ruby, PHP, Perl and Python and run them in the ‘Cloud’.

As a first exercise I wanted to check that I was able to get a simple Task board up and running. A good tutorial to create such a simple application with Pyramid can be found here.

After signing into OpenShift you can create a new application in the dashboard. Make sure that before doing so you have your namespace setup and your public ssh key configured in OpenShift. After creating the application a git repository is created for you. Simple clone this so you have a local working copy on your machine.

Now have a look inside you local working copy. You will find the directories data, libs, wsgi and some files like a README and the python setuptools related setup.py. Let’s start with editing the setup.py file:

from setuptools import setup

setup(name='A simple TODO Application to test OpenShift Features.',
      version='1.0',
      description='An OpenShift App',
      author='Thijs Metsch',
      author_email='thijs.metsch@opensolaris.org',
      install_requires=['pyramid'],
      classifiers=[
                     'Operating System :: OS Independent',
                     'Programming Language :: Python',
                    ],
     )

Please note the install_required parameter. Using this parameter will ensure that during deployment of you app the necessary requirements get installed – in this case Pyramid.

The following steps are pretty straight forward. The file application in the wsgi directory is as the name states a simple WSGI app. What we need to do is edit this file and let it call the todo app:

#!/usr/bin/python

import os

virtenv = os.environ['APPDIR'] + '/virtenv/'
os.environ['PYTHON_EGG_CACHE'] = os.path.join(virtenv, 'lib/python2.6/site-packages')
virtualenv = os.path.join(virtenv, 'bin/activate_this.py')
try:
    execfile(virtualenv, dict(__file__=virtualenv))
except IOError:
    pass

from todo import application

Please note that the file has no ‘.py’ extension.

Now we are ready to create the finally application. Please have a look at this tutorial as the code will almost be identical.

Create a file todo.py and follow the tutorial as described. Make sure you application runs locally. Put the ‘*.mako’ files in the subdirectory static under the wsgi directory. You can place the schema.sql file in the data directory. We will be using a sqlite database which will also be place in there.

The final step is to alter the todo.py file and remove the __main__ part. Instead we will introduce the following application function:

here = os.environ['OPENSHIFT_APP_DIR']

def application(environ, start_response):
    '''
    A WSGI application.
    
    Configure pyramid, add routes and finally serve the app.

    environ -- the environment.
    start_response -- the response object.
    '''
    settings = {}
    settings['reload_all'] = True
    settings['debug_all'] = True
    settings['mako.directories'] = os.path.join(here, 'static')
    settings['db'] = os.path.join(here, '..', 'data', 'tasks.db')

    session_factory = UnencryptedCookieSessionFactoryConfig('itsaseekreet')

    config = Configurator(settings=settings, session_factory=session_factory)

    config.add_route('list', '/')
    config.add_route('new', '/new')
    config.add_route('close', '/close/{id}')

    config.add_static_view('static', os.path.join(here, 'static'))

    config.scan()

    return config.make_wsgi_app()(environ, start_response)

When done we can push the code to the repository. When done you can visit you application at the given URL.

With this I’ve been able to create the app http://todo-sample.rhcloud.com/ and I also deployed my OCCI example service: http://occi-sample.rhcloud.com/. As you can see pretty straight forward & fast and of course fun!

What would be fun is to create a simple unittesting framework for OpenShift. For now you can find the code pieces at github.

The Power of Python & Solaris

June 16th, 2011 • Comments Off on The Power of Python & Solaris

Here is a presentation I gave today to demo the power of Python and Solaris. It’s about creating a fictitious service similar to no.de or Google App Engine but with Python & Solaris. Warning: contains OCCI and DTrace!

OCCI and More

November 15th, 2010 • Comments Off on OCCI and More

Busy times – but this post nicely wraps up what is going on regarding OCCI!

Deploying your (RESTful) python app in a PKI secured environment

August 1st, 2010 • 4 Comments

Now assume you have written an RESTful python application which you want to deploy in a secure manner. Many environments use a PKI security setup using X509 certificates. The good news is that you can do this. Install apache and the mod_wsgi module. On an Ubuntu Server a apt-get install libapache2-mod-wsgi apache2 will do.

Now simply add a site to your apache2 configuration – Normally located in /etc/apache2/sites-available:

WSGIPythonPath <python path>
    
    Listen 81
    NameVirtualHost *:81
    <VirtualHost *:81>
        ServerAdmin root@localhost
        ServerName localhost
    
        SSLEngine on
        SSLCertificateFile <path to cert>/newcert.pem
        SSLCertificateKeyFile<path to cert>/newkey.pem
        SSLCACertificateFile <path to cert>/cacert.pem
        SSLVerifyClient require
        SSLVerifyDepth 2
    
        SSLOptions +StdEnvVars
    
        WSGIScriptAlias / /<path to your service>/service.py
    
        ErrorLog /var/log/apache2/service.error.log
        CustomLog /var/log/apache2/service.log common
    </VirtualHost>

That’s it! The python app is now available on localhost:81 – Apache will ensure that the client certificate is authenticated against the CA! The statement SSLOptions +StdEnvVars ensures that the according headers are forwared to your python application so you also verify the user by his DN defined in the certificate.

Why Standards? – another point of view

March 19th, 2010 • Comments Off on Why Standards? – another point of view

During the past days there where several events where the topic ‘Why Standards’ was discussed. A writeup/summary of one of this events can be found here. Now read the following quote (out of context – I know :-)):

The people on standards bodies are in danger of speaking in an echo chamber. After a while, all they can hear is themselves

I do not agree with this. I will not comment on the ‘why standards’ and ‘we need standards for interoperability’ topics. But I want to raise one point: Why not see Standards bodies as Thinktanks? I mean so many people come together and bring in so many different opinions and points of views – which is very good so the solution (I do not call it standard now) will be cool (technology). I talked to so many people in the past days and all agreed that e.g. OCCI has some cool ideas. And we reached that by inviting all kinds of people with alls kinds of backgrounds to help create this cool thing. Okay we had our fights but somehow we reached consensus and I bet that a research lab of a company would have never come to the point where we are – just because they do not have all those different views.

Important is that you talk openly – if you have strict IPRs as a Standard Body and you’re not allowed to tell other people – you might indeed end up in ‘talking to yourself’.

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