Automatic Server Bootup on Power Failure

Imagine a power failure where your servers are running. Of course, they should be plugged into a UPS, but what if that goes down too? Your server will power off.

When the power comes back, your server will remain quiet unless you tell your servers to come back to life by themselves.

There are 2 things you must do in the BIOS to make this happen.

1. Tell the server to bootup after a power failure. This is the AC Power Loss Restart option in the BIOS. This should be set to On.
2. Ignore a missing keyboard. There is an area in the BIOS that handles halting on errors. It should be set so that it ignores keyboard errors. If this is not ignored, the server will wait for the user to press F1.

Rails 3.0: Installing Haml

Installing Haml is easy. Open up Gemfile.

gem 'haml'

Install.

bundle install

Now start naming your HTML files with a .haml extension, such as index.html.haml.

Cheat Sheet

Here's a quick cheat sheet to get you started.

#id
.class
%tag
%a{ :href => 'http://wesleymwwong.blogspot.com' }
/ HTML comment
= output
&= escaped output
!= not escaped output
- ruby
-# ruby comment
#{ inline ruby }
:javascript
!!! strict
!!! 5

References

• Haml

Why Haml?

When things are modular, simplicity and understanding have a chance to precipitate. Working with something that deals with a multitude of responsibilities is mentally tiring.

When using markup like HTML, there is a distinction between structure and layout. HTML provides the structure and CSS provides the layout. You should be able to separate out the two. The HTML should still make sense and be organized even without the CSS. This idea is very well demonstrated with CSS Zen Garden.

Inline CSS, I Banish Thee!

So where does Haml come into all of this? With Haml, I find it very hard to use inline CSS. Some may think this is a disadvantage because you can't do quick tweaks (read hacks). Hacks are usually done in the moment with the thought of fixing it up afterwards. Unfortunately, these usually end up sticking around permanently since it works and there is always something more important to do. You end up with HTML that does more than structure. With Haml, you are more inclined to let CSS handle the layout.

My Poor Fingers

Haml saves you a lot of keystrokes. It is much less verbose than HTML and ends up saving you a lot of time. With less characters required, it is easier to see the structure of the entire page at a glance, which helps once you move onto styling the page with CSS.

This Looks Familiar

Once you start converting your HTML to Haml, you'll notice something. It kind of looks like CSS! Because of this, it makes the CSS easier to write and understand.

Haml

If you have time, check out Haml and let me know what you think.

Rails 3.0: Cucumber + Mocking

I know. Cucumber is used for integration tests. Integration tests and mocking shouldn't even be in the same sentence. However, there are times when practicality trumps theory.

For instance, emails. How do you ensure that emails have been sent/received?

Another example is MailChimp. When a user signs up, you add them to a MailChimp list. Now, whenever you need to create a user, your app hits MailChimp. Since you are suppose to start with a clean slate, you now need to clean out the MailChimp list. This gets tedious and time consuming.

To speed things up, you may want to mock certain tasks like these.

Cucumber supports RSpec mocking (aka doubles) pretty easily.

Open up features/support/local_env.rb (or your custom config file for Cucumber)

require 'cucumber/rspec/doubles'

Done! Enjoy!

(Just as a note, I would test MailChimp without mocking when testing signup. I would mock it out in all other cases. Unfortunately, I haven't figured out how to test emails for real. If you have any suggestions, please leave a comment. I would love to hear it!)

Rails 3.0: Devise + Mongoid + RSpec

Devise removes the mundane job of writing all the code required to handle a user account. Plus, it supports Mongoid.

The following is a non-exhaustive list of tasks Devise takes care of for you:

• signup
• forgot/reset password (including emails)
• confirmation emails
• password encryption
• login
• logout
• editing account info
• locking accounts
• session expiration

All this is available out of the box. Along with the goodies that are pre-packaged, Devise is fully customizable.

Installation

Open Gemfile

gem 'devise'

Install

bundle install
rails generate devise:install

You will need to setup your mailer if it isn't already setup. Devise depends on the default host being set, so ensure the following is set

# ... other mailer settings
config.action_mailer.default_url_options = { :host => 'localhost:3000' }

Don't worry! Devise is smart and has already detected that you are using Mongoid at this point and not ActiveRecord. It has also created config/initializers/devise.rb. This is where you can configure Devise. Take some time to familiarize yourself with all the options and uncomment any that you would like to use. I'll wait.

Test Helpers

If you are using RSpec, create spec/support/devise.rb with

RSpec.configure do |config|
  config.include Devise::TestHelpers, :type => :controller
end

Now you have access to things like

sign_in @user
sign_out @user

Create a User model

It is time to create a User!

rails generate devise user

This generates a user model at app/models/user.rb with some Devise specific lines of code. Include the modules that you want and remove the ones you don't.

Believe it or not, Devise is now properly hooked up and ready!

Routes

Devise automagically generates all the user routes required for handling the user account. If you look in config/routes.rb, you'll notice

devise_for :users

To see all the routes

rake routes

You will notice a bunch of user routes. Fire up your server and navigate to localhost:3000/users/sign_up. Voila!

As a quick reference, here are some useful routes:

• signup: new_user_registration_url
• edit account: edit_user_registration_url
• login: new_user_session_url
• logout: destroy_new_user_session_url

References

I encourage you to take a look at the Devise home page as there is a wealth of information there.

https://github.com/plataformatec/devise

Ubuntu: Installing Fonts

It's very easy to install fonts in Ubuntu. Fonts usually come in a zip file. There may be several different versions of the same font with different extensions. I've currently tried this with ttf and otf fonts.

System-wide fonts are located at /usr/share/fonts. However, I prefer to keep things to myself, so I will install it in my home directory.

Create a .fonts directory in your home if it doesn't exist already.

mkdir ~/.fonts

Extract your font to the .fonts directory. You only need to extract one of the font versions. For example, if the zip file contains both myfont.ttf and myfont.otf, you only need to pick one of them, like myfont.ttf.

Refresh the font cache.

sudo fc-cache -f -v

If you had an application open, now would be a great time to restart it. You should now see the new font.

Mongoid: autocreate_indexes

Indexes help make your database reads faster, but has the downside of making your database writes slower. Either way, you will come across the need for indexes at some point.

Mongoid has a flag called autocreate_indexes. This flag tells MongoDB to create the indexes every time a class is loaded. This is set to false by default. However, when you add an index to a model, your application will complain since there is no index in MongoDB yet.

To get around this, you can set autocreate_indexes to true. You only want to do this for development and test since this can be slow. For staging and production, you will need to log into MongoDB and create an index manually before pushing your code.