26 Oct 2007

Single Table Inheritance validates_uniqueness_of Problem

RubyonRails, Technology, rails, ruby, web development posted by Akhil Bansal

Consider a case of STI where:

Now try following at console:

This will let you create three records in users table with same name, validates_uniqueness_of written in User class has no effect on it. validates_uniqueness_of automatically scoped with class names, that means it will not let you create two managers with same name or two customers with same name or two users with same name.

If you want uniqueness of an attribute in overall table, put the following code in some file in your lib dir and require that file in environment:

And then use validates_overall_uniqueness_of instead of validates_uniqueness_of.

13 Sep 2007

Deploying rails application with pound as a Balancer

RubyonRails, Technology, deployment, hosting, mongrel_cluster, pound, rails, web development posted by Akhil Bansal

Now a days Apache + mod_proxy + mongrel_clusters, Lighttpd + Mongrel cluster and Nginx + mongrel cluster are well known for deploying rails applications.

You can also deploy your rails application with pound(a reverse proxy, load balancer and HTTPS front-end for Web server).

First you need to setup mongrel_clusters for your rails application by issuing ” mongrel_rails cluster::configure -e production -p 8000 -a 127.0.0.1 -N 3 -c ./ ” inside the rails application root directory(on client machine). This will create mongrel_cluster.yml in config directory. You can change parameters in this command, as -p 8000 specifies that mongrel instances will start up on port number starting 8000, -a 127.0.0.1 specifies that mongrel instances will listen to the localhost, -N specifies the number of mongrel instances and -c specifies the rails root directory.

Now you need to install pound(if not installed) by issuing following commands(as root):

  • cd /opt/src
  • wget http://www.apsis.ch/pound/Pound-2.3.2.tgz
  • tar xzpf Pound-2.1.6.tgz
  • cd Pound-2.1.6
  • ./configure
  • make
  • make install

This will install pound in /usr/local/sbin/pound. In order to proceed further we need to create pound.cfg(pound configuration file) in /etc/pound/pound.cfg . Below is the content of pound.cfg:

Start mongrel cluster by issuing mongrel_rails cluster::start in you app root directory, start pound by /usr/local/sbin/pound -f /etc/pound/pound.cfg , now you are done. Pound is listening the port 80 and redirect all requests to mongrel instances running on 8000, 8001, 8002.

* Please Note that we have configured pound at port 80, if port 80 is being used by apache or any other application pound will not start. You need to stop any service using port 80, if it is apache then stop apache, change line ‘Listen 80′ to “Listen 8080″ and start apache.

In a specific case, when apache is running at some port (let say 8080), you may want to use apache to serve static content of your application, in order to reduce some load from mongrels. In that case use the following:

This will redirect all requests for image, stylesheets, javascripts, flash to apache. Now we need to configure apache to serve those static content. Just add a virtualhost for that:

Its all done. All requests for dynamic content at port 80 will be redirect to mongrel running at 8000, 8001, 8001 and requests for static content will be served by apache running at port 8080.

30 Aug 2007

Customizing CruiseControl build for RSpec

CruiseControl, RubyonRails, Technology, Tools, rails, ruby, web development posted by Akhil Bansal

Yesterday I posted about CruiseControl for Rails projects. It was working fine with all my rails projects using traditional test cases, But today I faced a problem with a project using RSpec. Actually, By default CruiseControl follows the following step to build:

  1. rake db:test:purge
  2. rake db:migrate
  3. rake test

This default was not working with my last project As I was using RSpec for my project. I found that we can overwrite default way of building by creating a rake task named cruise in our project. Means by building CruiseControl will run your custom rake task only, so you have to take care of all other things i.e. migrate etc.

Hence I created following rake task in RAILS_ROOT/lib/tasks/custom_cc.rake

and it worked for my rails project using RSpec.

24 Apr 2007

wanna add keyboard shortcuts to your web application?

javascript, rails, web development posted by Akhil Bansal

Today I was looking for some javascript to add keyboard shortcuts to my project. And after little search on google I came across a very cool and lightweight javascript library shortcuts.js .
This library allows you to make keyboard shortcuts on a fly.
Example:

Please visit this site to know more about this javascript library.

04 Feb 2007

apache proxy balancer + mongrel clusters and deploying application with capistrano

linux, rails, web development posted by Akhil Bansal

So you want to setup production server with mongrel clusters and apache proxy balancer, also wants to use capistrano for deployment, huh. Take it easy, its very simple.

You need Apache 2.2 or later on your production server, and the following ruby gems on your both machine(server and local):

  • capistrano
  • mongrel
  • mongrel_cluster

I haven’t mentioned rails and rake gem as we are deploying a rails application so these gems are obvious.

Lets install above gems (if not installed) by issuing:

Now make sure that the following modules are enabled (they are disabled by default) :

  • mod-rewrite
  • mod-proxy
  • mod-proxy-http
  • mod-proxy-balancer

to check if they are enabled issue ” /etc/init.d/apachectl -M ” on server, it will list all the enabled modules. For Debian systems all enabled modules are in /etc/apache2/mods-enabled directory and all available modules are in /etc/apache2/mods-available directory, to enable them issue ” a2enmod MOD_NAME “.

Now create the production database(on server) and update database.yml for production database settings.

After this configure mongrel by issuing ” mongrel_rails cluster::configure -e production -p 8000 -a 127.0.0.1 -N 2 -c ./ ” inside the rails application root directory(on client machine). This will create mongrel_cluster.yml in config directory. You can change parameters in this command, as -p 8000 specifies that mongrel instances will start up on port number starting 8000, -a 127.0.0.1 specifies that mongrel instances will listen to the localhost, -N specifies the number of mongrel instances and -c specifies the rails root directory.

Now its time to capistranize rails application, issue ” cap –apply-to ./ APP_NAME ” inside rails application root directory(on client machine), this will add two files(config/deploy.rb and lib/tasks/capistrano.rake) to the rails application. Edit deploy.rb according to your requirements. Also add the following code to deploy.rb :

Now on your local machine issue these two commands in only once ” rake remote:setup ” and ” rake remote:cold_deploy “, when you issue ” rake remote:setup ” it will prompt for the server password and create necessary directories on the server and ” rake remote:cold_deploy ” will deploy your code to the server. Next time whenever you want to deploy to the server you just need to issue ” rake remote:deploy ” not ” rake remote:cold_deploy “.

Now we are just one step back, we need to configure apache proxy balancer for mongrel instances. Add the following code to the httpd.conf file:

you need to change the above code according to you requirement. Also you need to restart apache server by issuing ” /etc/init.d/apachectl restart “. Now you are done.

But we also need to add a script to start mongrel instances when the server restarts, otherwise whenever the server restart there will no mongrel instance running.

Just create a file named mongrel_clusters (you can choose any name) in /etc/init.d directory with the following code:

You need to change the BASEDIR in the above code. Make this file executable by ” chmod +x /etc/init.d/mongrel_clusters ”
Issue these commands to add this script at system startup:

Debian: /usr/sbin/update-rc.d /etc/init.d/mongrel_clusters defaults
RedHat: /usr/sbin/chkconfig –add /etc/init.d/mongrel_clusters and /usr/sbin/chkconfig –level 2 /etc/init.d/mongrel_clusters on

Note: Use above instructions at your own risk, if your computer explodes its not my fault :-)

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