Installing Ruby on Rails is a hurdle for new Rails users. It's not a simple piece of software and there are a few things you need (like git and sqlite3) that must also be installed, and on top of all that Rails really needs specific versions of Ruby (that old 1.8.6 that came with your OS won't cut it) You can't just install it quickly and try out some Rails tutorials, until now. The Rails Installer from Engine Yard is a simple installer for Ruby, Rails and related tools for Windows and OS X (and possibly Linux in the future).
What's in the Box
Obviously Ruby on Rails and Ruby itself is included in the installer, but what else? Note, these version numbers are current as of June 2012, check the Rails Installer site for more up to date version numbers and possibly more or less items installed.
- Ruby 1.9.3 - Obviously, you'll need Ruby. But which version will you need? Rails 3 likes to run on 1.9.x and Rails 4 will require 1.9.3, so this is the version you should be using. The version that was installed by your OS (if you're using OS X or Linux) is probably too old to be useful.
- Rails 3.2.2 - This is what the installer is all about. This is the most recent stable release. If you want prerelease versions, this installer should work for you, you'll just need an extra gem command after the install.
- Git 188.8.131.52 - This is the version control tool most Rubyists and Rails developers use. This would require a separate install procedure if installing manually.
- SQLite - This is the database that's the most comfortable to use when developing Rails applications. It's simple, and not all that fast, but it's zero effort to set up and with this installer, zero effort to install.
- osx-gcc-installer - Installing GCC on OS X usually requires you to install XCode. XCode is really huge, several gigabytes. This installer will just install GCC without any of the XCode stuff you don't need and possibly don't want. This will save you a lot of time.
- RVM - This is a set of shell scripts that help you download, compile and install new versions of Ruby. You'll need this to upgrade your Ruby version, or install other versions to test your application on.
- JewelryBox - This is a GUI for RVM. Not necessary, but nice.
When you download the installer, you'll get a .app.tgz file. This file is an OS X app (which is technically a directory, not a file) in a gzipped tar file. Just run the tgz file either from your web browser or the finder and it will extract the file, exposing an app.
Running this app yields a familiar looking (if you've used Windows for any amount of time in the past 15 years, that is) installer wizard. Most apps on OS X do not have installer wizards, so this is a bit out of place. But as it needs to install a variety of packages, it's really appropriate here. There are only a few options in the beginning, nothing major, a typical "hit next until it starts installing" type of wizard.
The wizard will install quite a lot of files, so this might take a few minutes depending on the speed of your computer. I usually fire up the Activity Monitor and stop any programs using too much CPU time before running anything like this. Sometimes a website with Flash or a Java applet will be running and make a long installer even longer.
At certain points, it may look like the installer is frozen, but it will finish. I found that processes like mtmd were consuming most of my CPU, so this may not be Rails Installer's fault (mtmd is a daemon that deals with OS X Time Machine, it may be freeing up old backups to make space for new files). Just give it time.
Once it's finished, read through the readme PDF that launches. Close any relevant terminal windows and reopen them (this creates new Bash instances, and makes sure RVM is loaded) and you should be all ready to go. That was is, more or less just "run the installer, let it do its thing and restart your terminal windows." It can't be any more painless than that.
I don't think I'd recommend install Rails manually anymore, at least not for newbies. The Rails Installer works so well and has everything you'll need (short of an editor) that there's just no need to go through all that. Just run this installer and you're all set. If and only if you have the need to install different versions of things like SQLite or Git, or you just have to have that control over what software is installed, then do things manually. For everyone else, Rails Installer is what you're looking for.