Lincoln Loop

Running your own Self-Hosted Etherpad Instance

December 18, 2009 | code, open source | 12 comments

Etherpad is an amazing real-time collaborative editor with a very low barrier for entry (no logins, no additional software, etc.). In case you missed it, Etherpad was acquired by Google and after a community uproar decided to release their code as open source under the Apache License 2.0.

We were excited to get it up and running for our own internal use. What follows is a step-by-step guide of how we proped it up on our development servers.

Caveats:

1. We’re not Java guys, so if there is something we could be doing better, let us know.
2. The default setup of Etherpad is RAM hungry. Make sure you have at least 256MB free before you get started.
3. Our instructions are Ubuntu/Debian specific, but should be easy to translate to a different distribution.

Step 1: Get the Requirements

mkdir /opt/webapps/etherpad/ && cd /opt/webapps/etherpad/
sudo aptitude install ...

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Easy Fabric Deployment, Part 2: Multiple Committers and the Dreaded Umask

October 7, 2009 | code, django | 3 comments

In part 1, we showed how we use Fabric to update and deploy Django sites to our development server with a single command. This works great when you only have one developer pushing changes to the server, but what happens when multiple committers need to update the development server?

Linux File Permissions

Typically, the default permissions for newly created files are readable by everyone and writable by the owner (644 or -rw-r—r—). These permissions are determined by the processes umask, with the default being 022. Since we want multiple committers to be able to write to files on our development server, we need to change that to 002, creating group-writable files (664 or -rw-rw-r—).

The standard way to do this is to add the line umask 002 to /etc/profile. While that works great for interactive shells, it does not get called on non-interactive shells (the kind that ...

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Easy Fabric Deployment, Part 1: Git/Mercurial and SSH

September 22, 2009 | code, django | 3 comments

We’re firm believers in the practices described by the Continuous Integration method of software engineering. Among those are:

• Maintain a code repository
• Automate the build
• Automate deployment

We use git for our code repositories and Fabric to automate our build/deployment process. The tiny bit of overhead it take to write out a Fabric script pays off very quickly against the tedium and error-prone practice of manually building/deploying. In building our “fabfile”, we encountered a couple of issues that took a little head-scratching to work out.

Git and SSH Keys

Git, like Mercurial and others, confirms your credentials via an private/public key pair when used over SSH. We use gitosis to manage our private repositories, so managing everyone’s keys isn’t much of an issue. The problem comes when developers need to start pulling the repository on different machines. Our developers all push to a central ...

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Using Django Inside the Tornado Web Server

September 15, 2009 | code, django | 7 comments

Inspired by Eric Florenzano’s talk, Using Django in Non-Standard Ways (slides in PDF) at DjangoCon and the announcement of Tornado (tornadoweb.org), I decided to try building a small application using the Django Form library and Django ORM inside Tornado. The process proved easier than I expected, especially with Russell Keith-Magee being able to provide guidance on demand.

Step 1: Create Your Database

While Russell explained that it should be possible to get commands like syncdb running outside of a traditional Django project, it was outside the scope of this small experiment. Instead, I created a Sqlite database manually. For those of you that have forgotten how to do this, this will get you started:

# sqlite3 dev.db

sqlite> CREATE TABLE message (id integer primary key, subject varchar(30), content varchar(250));
sqlite> insert into message values(1, 'subject', 'cool stuff');
sqlite> SELECT * from message;

Step 2: Write Your ...

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Highlighting Named Anchors with jQuery

April 17, 2009 | code | 2 comments

I’ve always disliked the way named anchors (<a href=”#name”>...</a>) behave in browsers. It jumps your viewport to a different part of the page, but it’s rarely obvious which section you have landed on. If the page is long enough, the referenced section will start at the top of your browser, but where does it end? If the content is towards the bottom of the page, it may not be at the top of the page, but somewhere in the middle. And what if your content is in two columns? Or a table? What you’ve linked to becomes totally ambiguous.

Sphinx uses named anchors quite a bit, so I wanted something that would improve their usability for Django Best Practices. That’s when I dug up this clever little jQuery snippet from our code vault.

// highlight and fade background on named anchors
// requires jquery.color.js ...

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Getting RequestContext in Your Templates

May 10, 2008 | code, django | 13 comments

Lately, we’ve been taking over projects from people who began building their first site in Django, but either got in over their head or just found they didn’t have the time to continue. As I review the existing code, the first issue I typically see is using the render_to_response shortcut without including the RequestContext, preventing context processors from being used in the templates. The standard symptom is when people can’t access MEDIA_URL in their templates.

Here are a few ways to add RequestContext to your templates.

Option #1: Adding RequestContext to render_to_response

The Django documentation recommends passing RequestContext as an argument to render_to_response like this:

from django.shortcuts import render_to_response
from django.template import RequestContext

def my_view(request):
    # View code here...
    return render_to_response('my_template.html',
                              my_data_dictionary,
                              context_instance=RequestContext(request))

This works, but as you can see, it adds a fair amount of repetitive code to your views ...

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Google App Engine First Impressions

April 8, 2008 | code, django | 2 comments

For those of you that have been hiding under a rock for the last 12 hours, App Engine is Google’s answer to Amazon Web Services. While it is less flexible in some senses (you don’t have a complete OS at your disposal), it does provide tighter integration for web applications and even includes a (somewhat crippled) version of Django out of the box.

I’m pretty excited about this mainly because I’m not a big fan of server administration, so I took a couple hours this morning to test it out. Here are some quick notes:

The Good

• It sort of works with Django
• Deployment is dead simple
• It handles user accounts and registration
• Every app gets a built in Admin Console with stats, version management and datastore CRUD capability
• You can add your own Python libraries
• And, of course, it will scale on the fly

The ...

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Reusable Django Apps and Forking

April 4, 2008 | code, django | 15 comments

One of the things that drew me towards Django was the idea of being able to create reusable applications that would sit on my PYTHONPATH instead of copied across multiple sites. Coming from WordPress, the constant security updates that required me to revisit old projects began to drive me mad.

Trouble in Paradise

With some real world Django experience under my belt, I find myself re-using apps all the time, but not how I originally expected. A fair amount of my client work comes from building content management systems, so I started out building a generic app like flatpages but more extendable and a blogging app. I dropped them in my PYTHONPATH and started adding them to INSTALLED_APPS on my projects.

Over time, they evolved and improved, but they started to handcuff me. I started thinking things like, “This would be a great feature for Project X, but it would ...

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Serving Django via CherryPy

March 25, 2008 | code, django | 13 comments

Background

A few months ago, I got sick of trying to deploy Django sites on my cPanel server and got a VPS at Slicehost. Thanks to SuperJared, setting up Apache/mod_python behind an Nginx frontend was a snap.

I started deploying and migrating sites to the new server and kept an eye on my server resources via Munin. I had about 10 sites running on a 1GB Slice, but the Apache processes were hogging all the RAM. Restarting Apache would bring memory usage down to around 500MB, but within a couple of hours, it would be using all my available RAM, with individual proceesses using as much as 120MB.

I started asking questions and trying different options including mod_wsgi, verifying projects weren’t in debug mode, etc. Nothing made a difference.

CherryPy to ...

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Django FormMail Clone

March 13, 2008 | code, django | 5 comments

Here’s a little nugget I just posted to Django Snippets. It emulates the behavior of an old Perl script I used way back when, FormMail.pl.

I often find myself needing to build a form whose contents get emailed to the site owner(s). This class let’s you call form.notify() on any form that is a subclass of it to have the fields ordered and sent in a plain text email to all users that are flagged as staff.

from django import newforms as forms
from django.contrib.auth.models import User
from django.contrib.sites.models import Site
from django.core.mail import send_mail

class FormMail(forms.Form):
    def notify(self):
        """
        Sends an email to all members of the staff with ordered list of fields
        and values for any form that subclasses FormMail
        """
        site_name = Site.objects.get_current().name
        form_name = self.__class__.__name__
        subject = '%s %s Submission ...

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Better Use of Newforms

March 13, 2008 | code, django | 4 comments

The newforms library is a huge time-saver, but when I first started using it, I still found myself writing tedious repetitve code to get it to function how I wanted. While I could get away with it on smaller sites, I recently built a site with some big forms on it and decided to improve my process.

HTML Rendering

First off, {{ form }} or {{ form.as_p }}, rarely cut it in real world apps. We need to be able to customize our forms to improve the layout or add extra information. I started using inclusion tags to render the form fields and labels. Here is my trivial inclusion tag:

@register.inclusion_tag('_display_field.html')
def display_field(field, alt_label=''):
    """
    Print HTML for a newform field. 
    Optionally, a label can be supplied that overrides the default label generated for the form.
    
    Example:
    {% display_field form.my_field "My New Label" %}
    """

    if alt_label:
        field.label = alt_label
    return { 'field ...

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Basecamp SVN Integration

May 4, 2007 | code, subversion | 3 comments

As promised, here is the follow-up to the SVN for Web Developers post, Basecamp integration.

Why?

Transparency is very important to my business. The #1 complaint I hear about web developers is that they rarely meet deadlines and the client has no idea what is happening with the work until one day it magically appears. To combat that, I use Basecamp to lay out milestones for all my projects. I’ve found that even if a project takes longer than a client would like, as long as they can count on a date that it will be delivered, they’re happy.

Milestones are usually pretty spread out and don’t give clients a good idea of what I’m doing day-to-day to meet them. Writing each Subversion commit to Basecamp gives my clients quick access to the current status of their project.

How?

Luckily, all the hard work is done ...

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WordPress Plain Text Paste Plugin Version 0.3

January 25, 2007 | code, wordpress | 13 comments

Get it while it’s hot:

• NDS Paste 0.3 (gzipped tar)
• NDS Paste 0.3 (zip)

This plugin adds buttons to the WordPress rich text editor (TinyMCE) for pasting in clipboard content as plain text. Don’t trash your layout by pasting in text from Microsoft Word anymore.

Thanks to the TinyMCE paste plugin now being a part of the WordPress distribution, the plugin is now just one file. Extract nds-paste.php and upload it to your wp-content/plugins folder.
If you have a previous version of the plugin installed, delete the nds-paste folder from your plugins directory.

This plugin is only compatible with WordPress versions 2.1 and newer. Here is the 2.0x compatible version.

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WordPress Plain Text Paste Plugin

August 31, 2006 | code, wordpress | 49 comments

This plugin adds buttons to the WordPress rich text editor (TinyMCE) for pasting in clipboard content as plain text.

Go ahead and take it for a spin. Extract nds-paste folder from the archive and copy it to wp-content/plugins.
nds-paste-0.2.zip
nds-paste-0.2.tar.gz

Developers note: You should be able to ...

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eCheck.net Module for ZenCart

January 10, 2006 | code | No comments yet.

This is an add-on payment module for Zen Cart that will allow you to accept electronic checks via Authorize.net’s eCheck.net service. It was built using the existing Authorize.net (AIM) module as a template.

This module is released under GPL and is provided on a “works for us” basis. We accept no responsibility for any issues that may arise from using or installing this module.

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