This guide enables you to install (ruby-build) and use (rbenv) multiple versions of ruby, isolate project gems (gemsets and/or bundler), and automatically use appropriate combinations of rubies and gems.
# Ensure system is in ship-shape.
aptitude install git zsh libssl-dev zlib1g-dev libreadline-dev libyaml-dev
# Install rbenv for managing enabling of multiple rubies.
git clone git://github.com/sstephenson/rbenv.git ~/.rbenv
echo 'export PATH="$HOME/.rbenv/bin:$PATH"' >> ~/.zshrc
echo 'eval "$(rbenv init -)"' >> ~/.zshrc
exec $SHELL
# Install the ruby-build plugin for easy building of rubies.
mkdir -p ~/.rbenv/plugins
cd !$
git clone git://github.com/sstephenson/ruby-build.git
cd where/ever
# Install a couple rubies
rbenv install 1.8.7-p358
rbenv install 1.9.3-p125
rbenv rehash
# Try out a ruby.
rbenv shell 1.9.3-p125
# Enable a newly installed ruby, persistently, globally.
rbenv global 1.9.3-p125
# Enable a ruby persistently just for this directory.
rbenv local 1.8.7-p358
rbenv rehash
# Install bundler, create a Gemfile, install to project.
gem install bundler
>Gemfile <<<'gem "ronn"'
bundle install --path vendor
bundle exec gem env
# (OPTIONAL: for those who maintain gems or have myriad projects)
# Install rbenv-gemset, create a gemset, install a gem, use it.
cd ~/.rbenv/plugins
git clone git://github.com/jamis/rbenv-gemset.git
rbenv gemset create 1.9.3-p125 helloset
>.rbenv-gemsets <<<helloset
rbenv gemset active
gem install ronn
rbenv rehash
rbenv gemset list
Continue reading for explanations and a few more goodies…
This covers the process of setting up rbenv and its plugins, and also
touches on moving from RVM to rbenv. This is suited for development
environments, but not needed for production. This does not include anything
about rails (but does ensure you’re well set up and configured to install it).
And none of this should require sudo. You may want to consult the
individual project pages at some point to learn more, but this guide should
contain — standalone — every setup instruction needed for all the tools to work.
The two things to accomplish:
- Having at least one reliable locally installed non-system Ruby
- Project-specific Gemsets OR project-local gems
These steps have been tested primarily on Arch and Ubuntu linux. Examples are using some simple Zsh syntax which is slightly different from bash.
I’ve loved using RVM. It did do a surreptitious thing with my environment (a
shell file clobber setting) that I still don’t have a handle on (beyond
overriding things with shell functions). And it’s a little too sophisticated
to keep in my head everything it’s doing. If rbenv can eliminate any of the
magic of environment management, then I’ll give it a go.
My experience is also proving that most of this setup is not necessary for servers. There it’s working out best to just install an up-to-date ruby from source (via Sprinkle).
Git it.
% git clone git://github.com/sstephenson/rbenv.git ~/.rbenv
Enable it.
% echo 'export PATH="$HOME/.rbenv/bin:$PATH"' >> ~/.zshrc
% echo 'eval "$(rbenv init -)"' >> ~/.zshrc # or equivalent
% exec $SHELL
You haven’t done anything interesting yet. Hang tight.
For more rationale details, consult the rbenv
project page.
Your system should have gcc et al installed already. In Ubuntu this is
build-essential and in Arch you’ve already got them, of course.
Install Ruby-Build:
% mkdir -p ~/.rbenv/plugins
% cd ~/.rbenv/plugins
% git clone git://github.com/sstephenson/ruby-build.git
Now we’re done manually installing things to specific places. Ruby-Build will do the rest of the dirty work to configure, make, install, etc.
% cd ~/anywhere
Packages you’ll want installed in order for your rubies to configure to their fullest potential (apt packages):
libssl-dev zlib1g-dev libreadline-dev libyaml-dev flex gettext
Find out which rubies are available. Wow, you can even tab-complete these:
% rbenv install 1.8.7-p«tab»
1.8.7-p249 1.8.7-p302 1.8.7-p334 1.8.7-p352 1.8.7-p357 1.8.7-p358
Get a few (be patient):
% rbenv install 1.9.3-p125
% rbenv install jruby-1.6.7
% rbenv install rbx-2.0.0 # rubinius; why not
You need to “rehash” to regenerate rbenv’s ruby “shim” after installing a
new ruby.
% rbenv rehash
Now do it again for practice:
% rbenv rehash
You’re going to do that almost every time you install a gem to generate
shims for executables. Get used to it or make rbenv install an alias to also
rehash:
# Abbreviation for "gem install".
gi() { gem install $@; rbenv rehash; rehash }
You’ve probably already got a system ruby installed. See them all now.
(I believe system ruby is not listed here.)
% rbenv versions
1.8.7-p358
1.9.3-p125 (set by /home/mde/.rbenv/version)
jruby-1.6.7
rbx-2.0.0-dev
You should know that these are all being installed to your ~/.rbenv/versions
dir.
Turn one on for persistent “global” use across your system (for your user anyway).
NOTE: RVM users: forget the verb use. Your new enablers are shell,
global, and local.
% rbenv global jruby-1.6.7
% ruby -ve 'puts "it works"'
jruby 1.6.7 (ruby-1.8.7-p357) (2012-02-22 3e82bc8) (Java HotSpot(TM)…
it works
Quickly switch back and forth in a session with: rbenv shell 1.«tab»
The local command is pretty cool — it lets you auto-enable a specific
ruby whenever you enter a directory.
% <.rbenv-version
zsh: no such file or directory: .rbenv-version
% rbenv local 1.9.3-p194
% <.rbenv-version
1.9.3-p194
It does so silently, so you might want to do something with your prompt to indicate what’s active.
% cd ..; cd -
<silently enabling 1.9.3-p194>
(If you intend to install ruby 1.8.7, you might or might not need this workaround.)
You can skip this section and go directly the next Bundler section if you want to just always install gems directly into your projects.
Use the rbenv “plugin” subtool rbenv-gemset.
% cd ~/.rbenv/plugins
% git clone git://github.com/jamis/rbenv-gemset.git
You should now have a new gemset command in rbenv:
% rbenv gemset «tab»
active create delete file list version
% rbenv gemset create 1.9.3-p125 helloset
NOTE: tab-completion is not yet working for the gemset command.
That set up a directory for you in
~/.rbenv/versions/1.9.3-p125/gemsets/helloset. But now it’s up to you to do the
other half manually: setting the name of your gemset. You need to create a
tiny file, in this case containing helloset.
% >.rbenv-gemsets
helloset
Now when you gem install (see “Bundler” section below) something it will go
to your helloset gem area.
You can combine use of multiple gemsets with it.
The big benefit to this setup is enabling each project to use a different set of differently versioned gems.
% cd $TMPDIR/hello
% >.rbenv-gemsets
helloset
Bundler is the tool for managing your project dependencies. In fact, we’ll (almost) never even install a gem directly, without Bundler. It even obviates the need for gemsets for many project use cases.
NOTE: Although the tool is called “Bundler,” its command is actually bundle.
This has caused some confusion. You’ll actually be fine whether you install
the bundle or bundler gem, but the command will always be bundle.
Now that you’re working with multiple rubies, every ruby will need its own bundler.
Now, what gem do we actually have?
% whence -av gem
gem is /home/mde/.rbenv/shims/gem
gem is /usr/bin/gem
That didn’t make it too clear. Every ruby actually provides its own gem
command (er, maybe not 1.8?). Here’s how to see it:
% rbenv which gem
/home/mde/.rbenv/versions/1.9.3-p125/bin/gem
And what Bundler?
% rbenv which bundle
rbenv: bundle: command not found
Hmm. Now we can see that we need to install it manually. So this is
bootstrapping; it’ll be the only time we need to use gem directly for
installing. (bundler is also a good global gemset install; see below.)
% gem install bundler
…
% rbenv which bundle
/home/mde/.rbenv/versions/1.9.3-p125/bin/bundle
Great. That was quick and easy.
% which -a bundle
bundle is /home/mde/.rbenv/shims/bundle
bundle is /usr/bin/bundle
Now do it for all your rubies (and every time you install another ruby).
Like RVM, rbenv can do global gemsets, too (though I haven’t tried it yet).
% >Gemfile
source "http://rubygems.org"
gem "ronn", "1.3.2"
gem "nokogiri"
% bundle install
% cd ~/proj/foo
% rbenv shell 1.9.3-p125
% rbenv local «tab»
1.8.7-p358 1.9.3-p125 jruby-1.6.7 rbx-2.0.0-dev system --unset
% rbenv local jruby-1.6.7
Set a local persistent version.
% rbenv local rbx-2.0.0-dev
% cat .rbenv-version
rbx-2.0.0-dev
rbenv is a handful to be typing often. I presently use:
% alias rb=rbenv
though r and b are terribly distant to type on QWERTY.
Eventually new rubies will release and you’ll want to keep up. This means moving your installed gems along with them.
FIXME: I HAVEN'T DONE THIS YET
How do I install a gem to the system Ruby? I'm asking because I'm having trouble installing the latest (and reportedly last) 1.8.7. In general, how does one control which Ruby a gem is installed with?