Story of Compiling Kernel for Linux VServer

So I've been having a fun week.

This is my first time compiling a kernel and It should be straight forward as there are some helpful websites available on just this topic:

pre-requisites:
Patience. This will take an hour (or more) on a decent quad core machine.
gcc-<version>-plugin-dev
fakeroot
make-kpkg
libncurses5-dev

On compiling the kernel with the VServer patch
http://linux-vserver.org/Installation_on_Linux_2.6
On compiling a general kernel
http://www.howtoforge.com/kernel_compilation_ubuntu
On using your complete kernel
http://www.centos.org/docs/2/rhl-cg-en-7.2/buildkernel-bootloader.html

I was running the commands on a Ubuntu12.04 virtualbox machine, following the Vserver instructions and while running make, it kept running out of disk space.
A quick google tells me the result should be about 500MB at most, and doesn't even tell you what the result should be. My attempts kept running out of space after about 40 minutes and after hitting 8GB used space, of which almost all the room was taken up by vmlinux (2.9GB) and vmlinux.o (4.9GB)
Apparently this is not normal.
Eventually after making a virtual hd with a size of 100GB (of which the result was just short of 9GB itself) it appeared to say a build of bzimage in /arch/boot/x86 folder was completed. This I could never find anywhere in the folder.

I am currently compiling using the howtoforge.com link so we will see how much success I shall have later on.
Currently I am getting GCC error "array subscript is above array bounds" quite a lot but it appears to be ignoring it.

#Edit
Its been 2 hours. I didn't set CONCURENCY_LEVEL= because of fear of it crashing. Starting to wonder if it was a mistake given how long this is taking. It is still compiling and it has just moved from ./drivers to ./fs. My favourite file list, sudo du --max-depth=1 -h | sort -rh , reports file is at 7.9GB and growing.


7.9G .
4.8G ./drivers
689M ./net
602M ./fs
316M ./arch
259M ./sound
126M ./kernel
76M ./security
58M ./crypto
41M ./mm
34M ./lib
31M ./include
19M ./Documentation
17M ./block
13M ./.tmp_versions
6.8M ./firmware
6.2M ./ipc
5.0M ./grsecurity
4.7M ./init
4.1M ./tools
3.8M ./scripts
2.8M ./virt
2.0M ./debian
156K ./samples
92K ./usr

Foolproof FactoryGirl Sequence

Turns out Sequencing in FactoryGirl isn't as easy as it used to be.
Factory.next has been deprecated and the two obvious ways to make a sequence now throw Trait error or Attribute already defined error "FactoryGirl::AttributeDefinitionError"

The problem with this first approach is name. In a normal sequence you would just say name but I want to use it in the description too. This somehow makes FactoryGirl believe name is a trait.

FactoryGirl.define do
  
  sequence(:code) {|n| "#{n+1000}"}
  
  factory :course do |u|
    name "CS#{ generate :code }"
    description "#{name}, 1st year, 1st semester, Foundation Of #{name}"
  end
end

This next example has a problem with the description line. This causes the description to generate 2 more names and throw an AttributeDefinitionError because you now have more than 1 name generated.
For some reason you cannot get around it by making the name line name = Factory.generate :name because name becomes a Trait again.

FactoryGirl.define do
  
  sequence(:name) {|n| "CS#{n+1000}"}
  
  factory :course do |u|
    name
    description "#{name}, 1st year, 1st semester, Foundation Of #{name}"
  end
end

This is the only thing that works. Static forcing FactoryGirl to use the already defined name again using the |a| block in description. It isn't as pretty as it could be but I have to live with it unless someone can tell me a better way. There is probably a solution where you use an after_build tag but that makes it longer and more complicated unnecessarily and it would still be ugly.

FactoryGirl.define do
  
  sequence(:name) {|n| "CS#{n+1000}"}
  
  factory :course do |u|
    u.name
    u.description {|a| "#{a.name}, 1st year, 1st semester, Foundation Of #{a.name}"}
  end
end

Importing a CSV File from Upload in Rails >= 3

For some reason I found the documentation for CSV's really bad!

What I wanted to do is accept a file from a form and parse it into a list of users to be added to the database without saving the CSV file. (Note: I DO save the file via the Paperclip Gem for logging purposes but I do all the processing from the file before it is saved to the database.)

When you have uploaded the file using Form_Tag, the file is usually in params[:name] where :name is tag you gave to file_field_tag :name
If you are using a Form_For, which by the way is strange if you do not intend to save it to the model in question, the file will be in params[:model][:name] from  f.file_field :name
The magic part is to actually get to the file you need to call .read on it.

In the View remember to make it multipart to accept files.


<%= form_for @model, :html => { :multipart => true } do |f| %>
  <%= f.label :file %><br />
  <%= f.file_field :file %><br /> 
  <%= f.submit "Upload" %>
<% end %>



In the Controller require csv, you do not need to install it as a gem but you do need to require it as it is in standard library not core.

require 'csv'
def my_method
@lines = []
CSV.parse(params[:submission][:file].read) do |row|
      @lines << row
end


Replace the yellow bits with whatever you want to do with your CSV file.
Have fun!

Cucumber Feature Fun

This post will be expanded later. For now its just a note to self.
http://lmarburger.github.com/2009/09/cucumber-features-in-subdirectories.html
http://robots.thoughtbot.com/post/189412598/five-ridiculously-awesome-cucumber-and-webrat
NOTE TO SELF:
Cucumber will not find step definitions when running a single feature unless you tell it to require the whole folder.

Good
cucumber --require folder_with_step_definitions feature_file_I_want_to_run
Real life Example:
cucumber -r features features/courses #whole folder
cucumber -r features features/courses/new_course.feature #Single Feature

Bad
cucumber feature_file_I_want_to_run
#Will hit a wall of Step Definition Missing messages.
cucumber -r /features /features/courses #Will cause it to start looking from Root and not Rails.root causing File Not Found issues

CSS Basics

I'm a shameless novice at CSS at the moment.
I'm just going through CSS at http://cssxcountry.codeschool.com and Just thought I'd take a second to note down some things that need noting in my head about CSS. This post therefore will be messy and perpetually unfinished. You were warned.

Targetting CSS:
<h1> is caught with h1 { someCSS; }
class="coffee" is caught with .coffee { someCSS; }
and,
id="tea" is caught with #tea

Compound CSS: multi-word classes or IDs
First, if class="some thing"
the CSS for it will NOT be .some thing, it will be .some.thing as it is like having class="some" and class="thing"
Note: I don't know if having multiple classes in the CSS is even allowable.

Text:
center is a possible option for text-align
bold, italic and similar are in font-style

Other:
CSS does not care if it has a space between an attribute and value.
float: right;
float:right;
Both are valid.

Elements in CSS are space separated, whereas classes or IDs are attached. li p.intro#first

ShorthandCSS fragments from http://www.dustindiaz.com/css-shorthand/
Font
element {
  font-style: normal;
  font-variant:normal;
  font-weight: normal;
  font-size: inherit;
  line-height: normal;
  font-family:inherit;
}
font shorthand oddity: http://www.impressivewebs.com/css-font-shorthand-property-cheat-sheet/
The style, variant and weight can be ommited and the line-height is seperated by the / character.

Margin
element {
  margin-top: number+unit;
  margin-right: number+unit;
  margin-bottom: number+unit;
  margin-left: number+unit;
}

CSS positioning and Stacking images in rails.

So you are using Ruby on Rails and you want a method of stacking images on top of each other.
Your answer will probably involve CSS but many of the blog posts and Q&A posts I found weren't too descriptive so here is my shot at explaining this from the perspective of someone who doesn't use CSS often.

First a short bit on parents in CSS

When using CSS, having one style inside the other makes the top level the parent. In this example the div with the id of "container" is the parent of the div with the id of "contained".

<div id="container">
<div id="contained">
</div>
</div>
This does not work with class instead of id.

<div class="container">
<div class="contained">
</div>
</div>

And the CSS position

There are several good resources explaining position and I will just link to my favourites.
http://www.barelyfitz.com/screencast/html-training/css/positioning/

http://css-tricks.com/absolute-positioning-inside-relative-positioning/

Onto the good stuff

Our CSS files are in assets/stylesheets/ and the one we are using is the application wide stylesheet application.css.scss

The technique is to have a position:relative parent container, so that all position:absolute items inside are in the same place against the relative container. Note that the container needs a size, it will not take the size of absolute children. My images are 64px*64px big so I have to force my container to be that large or the next HTML element in the flow will overlap it.
In application.css.scss

#container {
    position:relative;
    width: 64px;
    height: 64px;
}
#image {
    position: absolute;
    top: 0;
    left: 0;
}
This lets you place images with the id="image" inside a div of id="container". In my code I stack City.png vertically above Grass.png in the view. Note in versions of Rails before 3.1 you need to use :id => instead of the new syntax id:
<div id="container">
<%= image_tag("Grass.png", id:"image") %>
<%= image_tag("City.png", id:"image") %>
</div>

Slim Rails Environment V2

Install Ubuntu Server with whatever settings you like (Default for me)

Remember that when using the xOrg system (xinit), you make it run from terminal with 'xinit' or 'startx'
You can open programs including the terminal from the right click menu in fluxbox.
You cannot copy-paste easily within xOrg unless you use terminator.

Update 24/06/12: !If you are using Bruce Scharlau's vm_template virtual box, and cannot Sudo apt-get anything due to 407 error, /etc/apt/apt.conf has the proxy defined in it and you can simply remove/replace the line as needed.

#System
sudo apt-get install xinit
sudo apt-get install fluxbox
sudo apt-get install build-essential
#Node.js  Rails will not run without a Javascript Engine
sudo apt-get install python-software-properties
sudo add-apt-repository ppa:chris-lea/node.js
sudo apt-get update
sudo apt-get install nodejs
#Rails
sudo apt-get install ruby1.9.1-dev
sudo gem install rails
#Using these three will install all the generic gems
#rails new cookbook
#cd cookbook
#bundle install

##Gem Specific
#Sqlite3
sudo apt-get install sqlite3 libsqlite3-dev
sudo gem install sqlite3

#Cucumber-rails
sudo apt-get install libxml2-dev libxslt-dev
sudo gem install cucumber-rails

#Postgresql gem
#Even if you do not use postgresql on your development machine, by just listing the gem anywhere in your gemfile, you need the libraries to make postgres work for bundle install. This is needed for Heroku.
sudo apt-get install libpq-dev #Note libpq NOT libpg

##Other Programs
#Terminator (Better terminal)
sudo apt-get install terminator

#Google Chrome (web Browser)
sudo wget -q -O - https://dl-ssl.google.com/linux/linux_signing_key.pub | sudo apt-key add -
sudo sh -c 'echo "deb http://dl.google.com/linux/chrome/deb/ stable main" >> /etc/apt/sources.list.d/google.list'
sudo apt-get update
sudo apt-get install google-chrome-stable

#sqlitebrowser (SQLite3 browser)
sudo apt-get install sqlitebrowser

#git
sudo apt-get install git



#Komodo ~Broken
~I have not yet got this working on xinit. Use Nedit or nano instead.
Edit: Or if you are using Ubuntu in a VM, start up a shared folder and run Komodo outside the VM

Aded 24/06/12:

My Workflow

Since this is useful and interesting to people, here is how I work:

When working, I have the virtual machine open on 1/3 of my screen. In it I have terminator open, with a tab for all git commands, a tab for all rails, system and developement commands, a tab for running rails s if I am testing in chrome, and a tab for running guard in (guard is a gem that automatically runs all rails tasks on file change) I will open a chrome window at the bottom of this area if I need to look at my app outside testing.

The only two changes I have made to Bruce's VM is I have made a symlink from /media/sf_vm_shared to ~/shared so it is in my home folder, and I have removed the proxy line in /etc/apt/apt.conf since I do not bring my desktop onto campus.

The remaining 2/3 of my screen has komodo edit running in the windows environment which edits the files through the shared c:/vm_shared folder.