GEMFILE(5)GEMFILE(5)NAMEGemfile - A format for describing gem dependencies for Ruby programs
A Gemfile describes the gem dependencies required to execute associated
Place the Gemfile in the root of the directory containing the associ‐
ated code. For instance, in a Rails application, place the Gemfile in
the same directory as the Rakefile.
A Gemfile is evaluated as Ruby code, in a context which makes available
a number of methods used to describe the gem requirements.
At the top of the Gemfile, add one line for each Rubygems source that
might contain the gems listed in the Gemfile.
Each of these _source_s MUST be a valid Rubygems repository. Sources
are checked for gems following the heuristics described in SOURCE PRI‐
If your application requires a specific Ruby version or engine, specify
your requirements using the ruby method, with the following arguments.
All parameters are OPTIONAL unless otherwise specified.
The version of Ruby that your application requires. If your application
requires an alternate Ruby engine, such as JRuby or Rubinius, this
should be the Ruby version that the engine is compatible with.
Each application may specify a Ruby engine. If an engine is specified,
an engine version must also be specified.
ENGINE VERSION (:engine_version)
Each application may specify a Ruby engine version. If an engine ver‐
sion is specified, an engine must also be specified. If the engine is
"ruby" the engine version specified must match the Ruby version.
ruby "1.8.7", :engine => "jruby", :engine_version => "1.6.7"
Specify gem requirements using the gem method, with the following argu‐
ments. All parameters are OPTIONAL unless otherwise specified.
For each gem requirement, list a single gem line.
Each gem MAY have one or more version specifiers.
gem "nokogiri", ">= 1.4.2"
gem "RedCloth", ">= 4.1.0", "< 4.2.0"
REQUIRE AS (:require)
Each gem MAY specify files that should be used when autorequiring via
Bundler.require. You may pass an array with multiple files, or false to
prevent any file from being autorequired.
gem "redis", :require => ["redis/connection/hiredis", "redis"]
gem "webmock", :require => false
The argument defaults to the name of the gem. For example, these are
gem "nokogiri", :require => "nokogiri"
GROUPS (:group or :groups)
Each gem MAY specify membership in one or more groups. Any gem that
does not specify membership in any group is placed in the default
gem "rspec", :group => :test
gem "wirble", :groups => [:development, :test]
The Bundler runtime allows its two main methods, Bundler.setup and
Bundler.require, to limit their impact to particular groups.
# setup adds gems to Ruby´s load path
Bundler.setup # defaults to all groups
require "bundler/setup" # same as Bundler.setup
Bundler.setup(:default) # only set up the _default_ group
Bundler.setup(:test) # only set up the _test_ group (but `not` _default_)
Bundler.setup(:default, :test) # set up the _default_ and _test_ groups, but no others
# require requires all of the gems in the specified groups
Bundler.require # defaults to just the _default_ group
Bundler.require(:default) # identical
Bundler.require(:default, :test) # requires the _default_ and _test_ groups
Bundler.require(:test) # requires just the _test_ group
The Bundler CLI allows you to specify a list of groups whose gems bun‐
dle install should not install with the --without option. To specify
multiple groups to ignore, specify a list of groups separated by spa‐
bundle install --without test
bundle install --without development test
After running bundle install --without test, bundler will remember that
you excluded the test group in the last installation. The next time you
run bundle install, without any --without option, bundler will recall
Also, calling Bundler.setup with no parameters, or calling require
"bundler/setup" will setup all groups except for the ones you excluded
via --without (since they are obviously not available).
Note that on bundle install, bundler downloads and evaluates all gems,
in order to create a single canonical list of all of the required gems
and their dependencies. This means that you cannot list different ver‐
sions of the same gems in different groups. For more details, see
Understanding Bundler http://gembundler.com/rationale.html.
If a gem should only be used in a particular platform or set of plat‐
forms, you can specify them. Platforms are essentially identical to
groups, except that you do not need to use the --without install-time
flag to exclude groups of gems for other platforms.
There are a number of Gemfile platforms:
ruby C Ruby (MRI) or Rubinius, but NOT Windows
ruby AND version 1.8
ruby AND version 1.9
ruby AND version 2.0
mri Same as ruby, but not Rubinius
mri_18 mri AND version 1.8
mri_19 mri AND version 1.9
mri_20 mri AND version 2.0
rbx Same as ruby, but only Rubinius (not MRI)
mingw Windows ´mingw32´ platform (aka RubyInstaller)
mingw AND version 1.8
mingw AND version 1.9
mingw AND version 2.0
As with groups, you can specify one or more platforms:
gem "weakling", :platforms => :jruby
gem "ruby-debug", :platforms => :mri_18
gem "nokogiri", :platforms => [:mri_18, :jruby]
All operations involving groups (bundle install, Bundler.setup,
Bundler.require) behave exactly the same as if any groups not matching
the current platform were explicitly excluded.
If necessary, you can specify that a gem is located at a particular git
repository. The repository can be public
(http://github.com/rails/rails.git) or private
(firstname.lastname@example.org:rails/rails.git). If the repository is private, the
user that you use to run bundle install MUST have the appropriate keys
available in their $HOME/.ssh.
Git repositories are specified using the :git parameter. The group,
platforms, and require options are available and behave exactly the
same as they would for a normal gem.
gem "rails", :git => "git://github.com/rails/rails.git"
A git repository SHOULD have at least one file, at the root of the
directory containing the gem, with the extension .gemspec. This file
MUST contain a valid gem specification, as expected by the gem build
command. It MUST NOT have any dependencies, other than on the files in
the git repository itself and any built-in functionality of Ruby or
If a git repository does not have a .gemspec, bundler will attempt to
create one, but it will not contain any dependencies, executables, or C
extension compilation instructions. As a result, it may fail to prop‐
erly integrate into your application.
If a git repository does have a .gemspec for the gem you attached it
to, a version specifier, if provided, means that the git repository is
only valid if the .gemspec specifies a version matching the version
specifier. If not, bundler will print a warning.
gem "rails", "2.3.8", :git => "git://github.com/rails/rails.git"
# bundle install will fail, because the .gemspec in the rails
# repository´s master branch specifies version 3.0.0
If a git repository does not have a .gemspec for the gem you attached
it to, a version specifier MUST be provided. Bundler will use this ver‐
sion in the simple .gemspec it creates.
Git repositories support a number of additional options.
branch, tag, and ref
You MUST only specify at most one of these options. The default
is :branch => "master"
Specify :submodules => true to cause bundler to expand any sub‐
modules included in the git repository
If a git repository contains multiple .gemspecs, each .gemspec repre‐
sents a gem located at the same place in the file system as the .gem‐
|~rails [git root]
| |-rails.gemspec [rails gem located here]
| |-actionpack.gemspec [actionpack gem located here]
| |-activesupport.gemspec [activesupport gem located here]
To install a gem located in a git repository, bundler changes to the
directory containing the gemspec, runs gem build name.gemspec and then
installs the resulting gem. The gem build command, which comes standard
with Rubygems, evaluates the .gemspec in the context of the directory
in which it is located.
If the git repository you want to use is hosted on GitHub and is pub‐
lic, you can use the :github shorthand to specify just the github user‐
name and repository name (without the trailing ".git"), separated by a
slash. If both the username and repository name are the same, you can
gem "rails", :github => "rails/rails"
gem "rails", :github => "rails"
Are both equivalent to
gem "rails", :git => "git://github.com/rails/rails.git"
You can specify that a gem is located in a particular location on the
file system. Relative paths are resolved relative to the directory con‐
taining the Gemfile.
Similar to the semantics of the :git option, the :path option requires
that the directory in question either contains a .gemspec for the gem,
or that you specify an explicit version that bundler should use.
Unlike :git, bundler does not compile C extensions for gems specified
gem "rails", :path => "vendor/rails"
BLOCK FORM OF GIT, PATH, GROUP and PLATFORMS
The :git, :path, :group, and :platforms options may be applied to a
group of gems by using block form.
git "git://github.com/rails/rails.git" do
platforms :ruby do
group :development do
In the case of the git block form, the :ref, :branch, :tag, and :sub‐
modules options may be passed to the git method, and all gems in the
block will inherit those options.
If you wish to use Bundler to help install dependencies for a gem while
it is being developed, use the gemspec method to pull in the dependen‐
cies listed in the .gemspec file.
The gemspec method adds any runtime dependencies as gem requirements in
the default group. It also adds development dependencies as gem
requirements in the development group. Finally, it adds a gem require‐
ment on your project (:path => ´.´). In conjunction with Bundler.setup,
this allows you to require project files in your test code as you would
if the project were installed as a gem; you need not manipulate the
load path manually or require project files via relative paths.
The gemspec method supports optional :path, :name, and :develop‐
ment_group options, which control where bundler looks for the .gemspec,
what named .gemspec it uses (if more than one is present), and which
group development dependencies are included in.
When attempting to locate a gem to satisfy a gem requirement, bundler
uses the following priority order:
1. The source explicitly attached to the gem (using :path or :git)
2. For implicit gems (dependencies of explicit gems), any git or path
repository otherwise declared. This results in bundler prioritizing
the ActiveSupport gem from the Rails git repository over ones from
3. The sources specified via source, searching each source in your
Gemfile from last added to first added.
March 2013 GEMFILE(5)