Archive for the ‘Ruby’ Category
Cookies in iFrames: how bashing my head on the table made them work in Internet Explorer
Posted by Giovanni Intini | Filed under Rails, Random Stuff, Ruby
While working on our TTGPassport our valiant team hit a wall that most programmers hit sooner or later when working with iframes: cookies won’t work with Internet Explorer, and you will lose your session.
The internet is full or remedies for this unnerving problem, most of them revolving on pseudo-magically setting the P3P header. I don’t believe in pseudo-magic, so I kept googling for answers, until I found this informing post.
I diligently ran through the suggestions but we had random session losses, with no reasonable explanation. We were setting our P3P header in a before filter (Rails application), like this:
class ApplicationController < ActionController::Base before_filter :set_p3p def set_p3p response.headers["P3P"]='CP="NOI DSP LAW NID"' end end
Fearing Rails could be the culprit I changed our Apache configuration to set the header on every request, using the following directive:
Header set P3P "CP=\"NOI DSP LAW NID\""
Unfortunately even bypassing Rails didn’t help. I was even unsure of why sometimes it worked and sometimes it didn’t (basically when explorer shows the evil red eye on the bottom of the page it means it’s blocking your cookies).
I started playing around with Firebug to see what could be the problem, and finally a little lightbulb lit on top of my head: the pages that broke the session didn’t have the P3P header, and instead they had an ETag header. That means something was adding the ETag and that the browser recalled the content of the page from its cache, thus bypassing P3P and upsetting explorer. I disabled ETags in Apache:
Header unset ETag FileETag None
Guess what? It didn’t work. Something was still setting the ETag header and bypassing my beloved and much needed P3P. The only culprit could be Ruby on Rails. I googled some more but nothing really told me how to disable ETags so I had to resort to some monkey patching:
module ActionController class Request def etag_matches?(etag) false end end class Response def etag? true end end end
I asked our strong, silent project manager to test it because I was crossing my fingers too hard, and, finally, it worked, no ETags and our P3P header where we expected it.
I hope you are reading this article because you had the same problem we had, and I hope it will help you as it helped us!
Continous Integration with RunCodeRun
Posted by Giovanni Intini | Filed under mikamai, Ruby, Ruby on Rails
Last thursday MIKAMAI hosted a Ruby Social Club meeting. Here’s the slides for my presentation.
Updated Language Redirect Extension for Radiant
Posted by Giovanni Intini | Filed under Radiant, Ruby
Thanks to the great work of netzpirat, the good old Language Redirect Extension has been updated to work with Radiant 0.8.0.
Thanks netzpirat!
Apache Vhost Templating
Posted by Giovanni Intini | Filed under Ruby
In Mikamai our deployment platform of choice is Ubuntu Linux. I like a lot the way Apache is set up on Debian based distributions, with the sites-available directory, but nonetheless creating new virtual hosts is a royal PITA.
Today I finally solved the problem once and for all via a super simple ruby templating script. Here it is, it uses a nice gem, optiflags, to parse the commandline arguments:
#!/usr/bin/env ruby require 'rubygems' require 'optiflag' module MyOptions extend OptiFlagSet flag "d" do description "The domain name the vhost should serve" long_form "domain" end optional_flag "a" do description "Email of the admin. If not specified defaults to info@domain" long_form "admin" end optional_switch_flag "w" do description "Adds www to non www redirection" long_form "www_redirect" end and_process! end flags = MyOptions.flags admin = flags.a ? flags.a : "info@#{flags.d}" domain = flags.d quoted_domain = flags.d.gsub(/\./, "\\.") TEMPLATE=<<-EOT <VirtualHost *:80> ServerName #{domain} ServerAdmin #{admin} DocumentRoot /var/apps/#{domain} <Directory /> Options FollowSymLinks AllowOverride None </Directory> <Directory /var/apps/#{domain}> Options Indexes FollowSymLinks MultiViews AllowOverride All Order allow,deny allow from all </Directory> ErrorLog /var/log/apache2/#{domain}.log # Possible values include: debug, info, notice, warn, error, crit, # alert, emerg. LogLevel warn CustomLog /var/log/apache2/#{domain}.log combined </VirtualHost> EOT REDIRECTION=<<-EOT <VirtualHost *:80> ServerName www.#{domain} ServerAdmin #{admin} RewriteEngine On RewriteCond %{HTTP_HOST} ^www\\.#{quoted_domain} RewriteRule (.*) http://#{domain}/$1 [R=301,L] </VirtualHost> EOT puts TEMPLATE puts REDIRECTION if flags.w?
I use it like this:
$ vhgen -d domain.com -w > /etc/apache2/sites-available/my_vhost $ a2ensite my_vhost
The unrestful programmer
Posted by Giovanni Intini | Filed under Programming, Ruby
Yesterday in Mikamai we had a Ruby Social Club meeting. I did a small presentation about the need to never stop learning. Here’s the slides:
Combinatorics for fun and profit
Posted by Giovanni Intini | Filed under Ruby
During my programming for fun moments I tend to always encounter a problem that needs to find combinations without repetitions for a set of data (numbers, objects, strings, letters, ...).
I have never been able to solve that problem in a way that satisfied me, and the languages I used didn’t have libraries for combinatorics that had a way to generate combinations without repetitions.
Yesterday a good friend of mine introduced me to the Set Puzzle, and, like I did for Word Challenge I had to try and attack the problem from a programming angle.
To do that I had to find once and for all a reusable way to generate combinations without repetitions. I did this time, and SetSolver was born.
You can check it out on GitHub, but I can’t help myself and not post the combinatorics code on this blog 
module ArrayExtensions def combinations_without_repetitions(k) combine(self, k) end private def combine(array, k) return [array] if k == array.size return array.collect {|e| [e]} if k == 1 results = [] array[0..(array.size - k)].each_with_index do |val, idx| results += combine(array[(idx+1)..-1], k - 1).collect {|e| [val, e].flatten} end results end end Array.class_eval do include ArrayExtensions end
Word Cheat, a simple anagram engine
Posted by Giovanni Intini | Filed under Ruby
Those of you who follow this blog since its inception will be aware of my obsession with word games, and specifically algorithms that solve word games.
Yesterday I was playing Word Challenge on Facebook, a simple game where you have to find all the words that can be composed with six random letters. After a couple of trials I decided to try and solve it with a ruby program, but since I didn’t want to use my previous code I decided to try a new approach to solve this problem.
First of all I took an extensive list of Italian words and filtered it to suit my needs, leaving only the words ranging from three to six letters.
Once I had my wordlist I had to build a data structure that could be used for fast anagrams retrieval, thus the WordHash class was born.
class WordHash attr_reader :words def initialize(wordlist) @words = {} wordlist.each do |word| if @words.has_key?(w = word.strip.signature) @words[w] << word.strip else @words[w] = [word.strip] end end end def get_anagrams(word) result = [] wordlist = @words.each do |k,w| result << w if word.contains?(k) end result end end
This class makes use of two helper methods I added to String, that I think should be really part of the Ruby standard library:
module StringExtensions def signature self.split('').sort.join end def contains?(search) !Regexp.new(search.signature.split("").join(".*")).match(self.signature).nil? end end String.class_eval do include StringExtensions end
The get_anagrams method is used to also get anagrams with a length less than that of the original word.
The whole project, complete with tests and a helper script is available on GitHub, feel free to contribute.
Also, big thanks to Stefano Cobianchi, who contributed with the contains? method, that I really couldn’t code
Two improvements to your Capfiles
Posted by Giovanni Intini | Filed under Capistrano, Drupal, Ruby
I have lately started using a pattern that has become quite common among capistrano users: setting the server names and locations in a task. Doing this allows you to have multiple deployment environments, like development, staging, production, and so on.
desc "deploy to development environment" task :development do set :deploy_to, "/var/apps/#{application}" role :web, "servername.mikamai.com", :primary => true role :app, "servername.mikamai.com", :primary => true role :db, "servername.mikamai.com", :primary => true set :user, "username" set :password, "secr3t" set :remote_mysqldump, "/usr/bin/mysqldump" set :db_user, "username" set :db_password, "secre7" set :db_name, "db_name" end
This technique has proven itself to be really useful, especially when clients start to ask for deployments on their test servers, and you still want to be able to deploy to your development servers.
While refactoring my Capfiles I also took the time to rewrite the drupal:db namespace, adding the much needed tasks that allow you dump the remote databases and download them to your development box.
namespace :db do namespace :dump do desc "Deletes old database dumps, leaves only the latest on the server" task :cleanup, :roles => :db do dumps = capture("ls -xt #{shared_path}/dumps").split.reverse run "cd #{shared_path}/dumps; rm #{dumps[0..-2].join(" ")}" end desc "Dumps the local database" task :local, :roles => :db do raise RuntimeError.new("failed dump") unless system "#{local_mysqldump} -u #{local_db_user} --password=#{local_db_password} #{local_db_name} > dump.sql" end namespace :remote do desc "Dumps the remote database" task :default, :roles => :db do filename = "#{Time.now.to_i.to_s}.dump.sql" run "cd #{shared_path}/dumps; #{remote_mysqldump} -u #{db_user} --password=#{db_password} #{db_name} > #{filename}" run "cd #{shared_path}/dumps; bzip2 #{filename}" end namespace :download do desc "Dumps and downloads the remote database" task :default do drupal::db::dump::remote::default latest end desc "Downloads the latest database dump" task :latest, :roles => :db do dumps = capture("ls -xt #{shared_path}/dumps").split.reverse get("#{shared_path}/dumps/#{dumps.last}", "./#{dumps.last}") end end end end
Legacy Path Handler, a Radiant Extension
Posted by Giovanni Intini | Filed under Radiant, Rails, Ruby, Ruby on Rails
We’re preparing to deploy the new Mikamai site (not up at the time of this post), that runs on the wonderful Rails-based RadiantCMS.
The VPS we’re deploying to runs on Phusion Passenger, and that means we can’t use mod_alias or mod_rewrite to 301-redirect the old URLs, already indexed by Google, to their new locations.
To solve this problem I wrote a little Radiant Extension, called LegacyPathHandler, that reads a simple list of URLs from a text file and does a 301 redirection on them before handling the control to Radiant’s default SiteController.
It works quite fine for us, but it has no specs/tests or documentation. Please feel free to contribute to the project if you feel you can improve it.
Deploying Drupal with Capistrano
Posted by Giovanni Intini | Filed under Capistrano, Drupal, PHP, Ruby
Mikamai, the company I work for, has just released Montalbano.tv, the companion site to one of the most successful TV shows in Italy.
I was the technical director of this Drupal based project, and while I was happy we chose Drupal, because it allowed us to deliver all the features they needed on time, I almost panicked when they told us the production setup would have two servers, both with database and web serving duties.
The database replication was standard MySql master-master setup, but I had to develop a strategy to keep the two code-bases on the two servers synchronized.
Being a Ruby programmer at heart, I selected the only tool that never fails me in circumstances like the one we had: Capistrano.
Unfortunately, while Capistrano is all easy to use with Rails, I had to write a custom Drupal-tailored Capfile.
Here it is, in its entirety, in case you ever need to deploy Drupal with cap (now I always deploy Drupal with cap, since I have the recipe ready ):
load 'deploy' if respond_to?(:namespace) # cap2 differentiator # Standard configuration set :user, "username" set :password, "password" set :application, "application.name" # I like to deploy the code in /var/apps # and then link it to the webserver directory set :deploy_to, "/var/apps/#{application}" # SCM Stuff configure to taste, just remember the repository # here I used github as main repository set :repository, "git@github.com:username/project.git" set :scm, :git set :branch, "master" set :repository_cache, "git_master" set :deploy_via, :remote_cache set :scm_verbose, true # Two servers, double fun # You really don't need app, web and db here, # but I used all of them just to be sure. # Usually only web is ok. role :app, "first.server.address.com" role :app, "second.server.address.com", :primary => true role :web, "first.server.address.com" role :web, "second.server.address.com", :primary => true role :db, "first.server.address.com" role :db, "second.server.address.com", :primary => true after 'deploy:setup', 'drupal:setup' # Here we setup the shared files directory after 'deploy:symlink', 'drupal:symlink' # After symlinking the code we symlink the shared dirs # Before restarting the webserver we fix all the # permissions and then symlink it to production before 'deploy:restart', 'mikamai:permissions:fix', 'mikamai:symlink:application' namespace :drupal do # shared directories task :setup, :except => { :no_release => true } do sudo "mkdir -p #{shared_path}/files" sudo "chown -R #{user}:#{user} #{deploy_to}" end # symlink shared directories task :symlink, :except => { :no_release => true } do sudo "ln -s #{shared_path}/files #{latest_release}" end end namespace :deploy do # adjusted finalize_update, removed non rails stuff task :finalize_update, :except => { :no_release => true } do sudo "chmod -R g+w #{latest_release}" if fetch(:group_writable, true) end task :restart do # nothing to do here since we're on mod-php end end namespace :mikamai do # symlinking to production namespace :symlink do task :application, :except => { :no_release => true } do sudo "rm -rf /var/www/montalbano" sudo "ln -s #{latest_release} /var/www/montalbano" end end # change ownership namespace :permissions do task :fix, :except => { :no_release => true } do sudo "chown -R www-data:www-data #{latest_release}" end end end