Getting MRI 1.9.2 on Ubuntu 11.10

The release of Ubuntu 11.10 (Oneiric) brings much-needed updates to the Ruby packaging. We can now get a sane Ruby environment in Ubuntu with a few commands.

sudo apt-get install ruby1.9.1-full
sudo update-alternatives --set ruby /usr/bin/ruby1.9.1
sudo env REALLY_GEM_UPDATE_SYSTEM=1 gem update --system

This sets up a fully working MRI 1.9.2 environment, with an up-to-date version of Rubygems.

Enjoy!

Quick Way Out of Ubuntu's Rubygems Jail

This post offers a quick method for overwriting the system-supplied RubyGems binary on Ubuntu (and any other Debian derivative) with a pristine version from the RubyGems authors.

Method
The following commands will do the trick.

sudo apt-get install rubygems-update

sudo /var/lib/gems/1.8/bin/update_rubygems

After installing the pristine version of RubyGems, you will have to re-install all your gems. This is because Ubuntu/Debian also modifies the path where RubyGems stores its gem data.

Motivation
Debian cripples RubyGems in various ways, to make it fit in with the overall Debian philosophy.

The most unfortunate change is that RubyGems will not update itself automatically, and we have to wait for Debian maintainers to package the updates. Another annoying change is that Debian's RubyGems will not install launcher scripts in /usr/bin, so we cannot use rails or rake by straight-forward gem installation.

While the path problem is easy to fix (sudo echo "PATH=/var/lib/gems/1.8/bin:$PATH" > /etc/profile.d/rubygems1.8.sh), there's no straight-forward solution for getting updated RubyGems. At the time of this writing, bundler (needed by the Rails 3 beta) requires RubyGems 1.3.6, and the version in Debian is 1.3.5.

I hope you have found this post to be useful, and I'm looking forward to your comments and suggestions.

Ruby on Rails Development Setup

This post documents my development setup for Ruby on Rails on Linux, MacOS X, and Windows. The Linux-specific instructions are geared towards Ubuntu, but should be easy to translate to other distributions.

Platform-Dependent Steps
The first part of the setup is installing the Ruby programming language, the Rubygems package management library, and the MySQL and SQLite database software. Due to the binary nature of the packages, the instructions are different for each OS.

Keep in mind that Windows and MacOS X differ in various ways from Linux, which will likely be your production environment. For best results, I strongly recommend installing Ubuntu as a dual-boot, or using Virtual Box to get an Ubuntu VM.

Ubuntu Linux
The steps below have been tested on a fresh installation of Ubuntu 9.10 Desktop.

1. Update your package repository: sudo apt-get update
2. Install Ruby: sudo apt-get install build-essential ruby irb rubygems libopenssl-ruby
3. Install MySQL: sudo apt-get install mysql-client mysql-server libmysqlclient-dev
4. When prompted, leave the MySQL root password blank. This will make it easy to share a database.yml file with the rest of your team.
5. Install SQLite:  sudo apt-get install sqlite3 libsqlite3-dev
6. Find out the system-wide RubyGems binary path (pick the one that is not in your home directory): gem env gempath
7. Add the path to the system-wide binary path: sudo echo "PATH=/var/lib/gems/1.8/bin:$PATH" > /etc/profile.d/rubygems1.8.sh
8. Reboot the system so the path change goes into effect.

MacOS X
The steps below have been tested on a fresh installation of MacOS X 10.6: Snow Leopard.

1. Install Xcode from Apple's Developer site, or from the MacOS installation DVD.
2. Go to the MySQL download site, and download the Mac OS X (package format) for your OS (Leopard: 10.5 x86, Snow Leopard: 10.5 x86_64). 
1. You don't have to register, there is a No thanks, just take me to the downloads! link on the mirror page.
2. Install the mysql- pkg file.
3. Install MySQLStartupItem.pkg.
   
4. Install (by double-clicking) MySQL.prefPane, and choose to Install for all users. Start the MySQL server, and check the Automatically Start MySQL Server on Startup box.
   
3. In the Platform-Independent Steps, substitute gem install mysql with the following command, taken from the Riding Rails blog: sudo env ARCHFLAGS="-arch x86_64" gem install mysql -- --with-mysql-config=/usr/local/mysql/bin/mysql_config

Windows
The steps below have been tested on a fresh Windows XP SP3 32-bit installation.

1. Install Firefox: www.getfirefox.com
2. Install the latest stable release of 7-Zip: http://www.7-zip.org/
3. Launch the 7-Zip File Manager (in Start > All Programs > 7-Zip). From the menu, select Tools > Options, and check .7z under Associate 7-Zip with. Click Ok to dismiss the dialog, and exit the file manager.
   
4. Go to the OneClick Ruby download site.
1. From the latest RubyInstaller, download the rubyinstaller-1.8.6 executable. Install in the default path c:\Ruby and "add Ruby executable to your path".
2. From the latest Development Kit, download the devkit- archive. Extract its contents in c:\Ruby
   
5. Go to the MySQL download site, and download the Windows MSI Installer (x86). 
1. You don't have to register, there is a No thanks, just take me to the downloads! link on the mirror page.
2. After downloading, do a Complete Install.
3. At the end of installation, check Configure the MySQL server now, and uncheck Register the MySQL server now.
4. When configuring the server, select Detailed Configuration, then Developer Machine, then Multifunctional Database. Accept the defaults, until the Install as Windows Service option shows up, then select both Install as Windows Service and Include Bin Directory in Windows PATH. For ease of development, don't change the root password (so it stays blank).
   
6. Go to the SQLite download site, under the Precompiled Binaries For Windows section. Download the sqlite- and the sqlitedll- zip files, and extract them into c:\windows\system32.
7. Restart your computer so the PATH changes go into effect.
   
8. You can go into a Ruby-enabled command prompt via Start > All Programs > Ruby 1.8.6 > Start Command Prompt with Ruby.
9. In the Platform-Independent Steps section, substitute gem install mysql with the following command. gem install mysql --source http://gems.rubyinstaller.org
   

Platform-Independent Steps
The second part of the development environment setup is identical in all OSes, with one small exception. The gem command should be executed with superuser privileges on Unix systems (Linux, MacOS X). To achieve that, all gem commands should be prefixed by sudo. For example, gem update would become sudo gem update.

Issue the following commands, and you're done setting up!

gem update --system

gem update

gem install rdoc 

gem install rails

gem install mysql

gem install sqlite3-ruby

gem install json mongrel ruby-debug-ide

Motivation
My post is intended to help the students in MIT's Web Programming Competition (6.470) who choose Rails as their back-end platform.

I hope you have found this post to be useful. Please leave a comment if you have trouble using the instructions above, or if you have a suggestion for improving these steps.

Quick Way to See Your Gems' Documentation

Summary
The fastest way to see the RDoc for your installed gems is to type the following command into a terminal, and point your Web browser to the address it returns (usually http://localhost:8808)
gem server

Details
The Web server created by the gem server command contains the RDocs for all the gems you have installed, unless you disabled RDoc generation when you installed your gems.


Motivation
I was used to either searching via Google, or going to a gem's RubyForge page to see the RDoc for the gem.

Initially, it seemed that the bit of effort is worth not having to learn some way to generate and bring up the RDocs myself. To my surprise, the procedure is very simple, and it's totally faster than browsing to some Web site that has the RDocs.

That aside, using a local server has the advantage that you'll see the RDocs corresponding to the exact versions of your gems. And, last but not least, RubyForge seems to be slowly falling into oblivion, and newer gems don't seem to bother publishing their RDocs.

I hope this post saves you some time.

Rebuild Your Ruby Gems If You Update To Snow Leopard

This post contains a command that you must absolutely issue if you are a Ruby developer upgrading to Snow Leopard.

The Commands
Update: Type the following command in terminal:

sudo gem update --system; sudo gem pristine --all

rubygems will produce some errors which are safe to ignore

For historical reasons, here's my initial solution to re-compiling all the native gems.
Fire up irb, and type the following command:
`gem list`.each_line {|line| system "sudo gem install #{line.split.first}"}

Motivation
Snow Leopard introduces a disrupting change: everything runs in 64-bit mode by default. Most importantly to me, ruby is now 64-bit. This is a problem when upgrading to Snow Leopard, as opposed to doing a fresh install, because the Ruby extensions in your old gems are probably 32-bit.

A quick solution to this problem is getting all the extensions rebuilt, which is done by reinstalling all the gems.

In case you're wondering, gem update won't do the trick, because it will not rebuild all your gems.

Symptoms
If you're lucky, you'll get a library loading error when trying to use some gem with an extension (example: json), and you'll figure out rather quickly that you need to reinstall the gem.

A subtle symptom of the same bug is experiencing slowdowns running a Rails development server. In my case, webrick was really slow - start-up took about 30 seconds. For this reason, it's better to re-compile all the gems, as oppose to fire-fighting load error messages.

I hope this post saves you some time.

Removing Default Ruby Gems on OSX Leopard

This post describes a quick way to remove the gems that come pre-installed on OSX Leopard.

Method
First, you should update your gems, so you have newer versions for all the gems you're about to remove. While you're at it, update rubygems as well.

sudo gem update --system

sudo gem update

Now blast the directory containing the gems that came with OSX.
sudo rm -r /System/Library/Frameworks/Ruby.framework/Versions/1.8/usr/lib/ruby/gems/1.8

If, for some reason, that directory does not exist on your system, you can see rubygems stores its gems by running gem env paths. Most likely, the old gems have already been cleaned.

Enjoy being able to clean up all the old gems on your system.
sudo gem clean

Warning
Removing the gems this way is permanent. If you don't like that thought, rename the 1.8 directory to 1.8.dead, and create an empty 1.8.  This way, rubygems doesn't see the old gems, but they are still around, if you need them for some reason. So, instead of rming,
sudo mv /System/Library/Frameworks/Ruby.framework/Versions/1.8/usr/lib/ruby/gems/1.8 /System/Library/Frameworks/Ruby.framework/Versions/1.8/usr/lib/ruby/gems/1.8.dead
sudo mkdir /System/Library/Frameworks/Ruby.framework/Versions/1.8/usr/lib/ruby/gems/1.8

Motivation
The pre-installed gems have been released 2 years ago, so they're really old by now. They need to go away. Doing a gem clean will fail to remove them. (tested with Rubygems 1.3.1 and below) What's worse, gem clean will fail to remove other old gems that you have installed so, after a while, you'll have a lot of cruft on your system.

I wrote this post because, up until now, I've been too lazy to figure out the gem cleanup situation. Now that I finally did, I want to make it easy for others to get their systems clean.

Conclusion
I've described a quick way to remove the old ruby gems that come preinstalled with OSX Leopard. This is useful because gem clean is non-functional in the presence of those gems. I hope you have found the post useful. Please comment if you have better or quicker solutions to this problem.

Post-install / post-update scripts for ruby gems

This post outlines a hack that allows a gem to run Ruby code when the gem is installed or updated, which in effect gives post-install / post-update hooks. The method described here works with any reasonable version of ruby and rubygems (I only tested as far back as ruby 1.8.4 and rubygems 0.9.4, and everything looked good.)

Summary
Add a fake extension, use extconf.rb to run your code and then simulate successful compilation. Use the links at the end for example code.


Detailed Description
RubyGems isn't supposed to run arbitrary code during gem installations, but it supports building extensions for gems. This is a really sweet feature, and makes rubygems a nice tool for cross-platform package management. That's good and all, but the part that we care about is that the process of building an extension starts by running extconf.rb in the extension's directory, which is responsible for producing a Make file that will orchestrate the building process.

Knowing this, the first thing that comes to one's mind is - let's add an extension to the gem, and put the hook code in extconf.rb. However, there's one more issue left. If rubygems believes that your gem's extension hasn't been built properly, it will not finish installing the gem, and it will spit out a nasty error message.

In order to work around that, we need to trick rubygems' build process, so we need to bypass 3 checks:

1. a Make file is generated - create an empty Makefile
2. make all and make install run successfully - generate a make file that contains empty all and install targets; create fake make binaries to cover the case when the user doesn't have a build environment (Linux/Mac: an executable make with a /bin/sh shebang should work; Windows: an empty nmake.bat should trick the Windows port of rubygems)
3. an extension binary is generated - create empty files your_extension_name.so and your_extension_name.dll
   

You can implement this yourself, or you can depend on my zerg_support gem, and use the method there, like the example code below does. I promise I won't mind if you copy-paste the code, so you don't have to take an extra dependency :)

I haven't tested out the Windows plan yet, but I have good reasons to believe it should work (I've built gems with real extensions on Windows some time ago).


Code Map
Adding an extension to your gemspec (assumes you're using hoe or echoe):
http://rails-pwnage.rubyforge.org/svn/trunk/zerg/Rakefile

Placing your hook in extconf.rb:
http://rails-pwnage.rubyforge.org/svn/trunk/zerg/ext/zerg_setup_hook/extconf.rb

Tricking rubygems into thinking an extension was built (see emulate_extension_install):
http://rails-pwnage.rubyforge.org/svn/trunk/zerg_support/lib/zerg_support/gems.rb