RPi Ruby on Rails

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Revision as of 20:02, 29 April 2012 by Erik (Talk | contribs) (Changed from 'problems' to more of a solution.)

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Installing Ruby on Rails on Raspberry Pi

This guide is aimed at developers, although it can be used by beginners if they know what they are after. It is provided as neither Ruby or Rails are included as standard in Debian "squeeze". Other Linux RPi distributions may contain this by default.

THE GUIDE IS STILL DRAFT; AND CAN HOPEFULLY BE OPTIMISED.

Start with a clean image of Debian "squeeze". There is not enough room on a standard 2Gb image. I tested with an 8Gb image, but you may get away with 4Gb.

The installation was all done from the basic (pre startx) command prompt.

This method uses the Ruby enVironment Manager (RVM), so first we must install all its prerequisites:

# Install prerequisites
sudo apt-get install -y git
sudo apt-get install -y curl
sudo apt-get install -y zlib1g-dev
sudo apt-get install -y subversion

Now we can use RVM straight from github using:

curl -L get.rvm.io | bash -s stable --rails

Note: With my default Debian image and keyboard map, it was very hard to get a | (pipe) character. I got it by pressing AltGr+|

When run, you will get some messages about requirements for Ruby. You need to scroll down (TODO Confirm this is necessary) until you see "Press 'q' to continue.", then press 'q'. Note the computer may not react straight away as it is 'thinking'. After a few seconds, the script will download and compile ruby 1.9.x and Rails. This takes a long time! (3 Hrs) Have a sleep and check in the morning. The above step has been successfully performed on a real RPi, but not managed to complete successfully on Qemu.

Now you should have ruby:

pi@raspberrypi:~$ ruby -v
ruby 1.9.3p194 (2012-04-20 revision 35410) [armv61-linux-eabi]

And you should have a rails command:

pi@raspberrypi:~$ rails -v
Rails 3.2.3

Open SSL

Despite having openssl installed, ruby seems to have a problem seeing it. I think this is a common linux problem. The following worked for me, but means waiting a few more hours.

pi@raspberrypi:~$ rvm reinstall 1.9.3 --with-openssl-dir=/usr/bin

JavaScript

Rails requires a JavaScript runtime. Any of the following listed here will do. I installed node.js using this blog by Tom Gallacher. (Note I had to use sudo when doing make install)

Testing Installation

In order to test the installation, let's create a simple project. In this example the name for our new project is school.

pi@raspberrypi:~$ rails new school
pi@raspberrypi:~$ cd school
pi@raspberrypi:~$ rails g scaffold Pupil name:string form:string
pi@raspberrypi:~$ rake db:migrate
pi@raspberrypi:~$ rails s

All being well you will now have a running server with database back end, which you can point a browser at.

Note: You can't use 'class' as a field name, so I chose 'form'.

If do the above in an X-windows terminal, then point the Raspberry-Pi browser to:

http://0.0.0.0:3000/pupils

You should then be able to Create, Read, Update & Delete (Often called CRUD) pupil records in your database.

Alternatively, if you have another computer on the same network, you can point its browser at the RPi substituting the 0.0.0.0 in the above address for the real RPi one. If you don't know the address of your RPi, then use the following command in a terminal:

ip addr