Provided by: ruby-bundler_1.16.1-1_all 
NAME
Gemfile - A format for describing gem dependencies for Ruby programs
SYNOPSIS
A Gemfile describes the gem dependencies required to execute associated Ruby code.
Place the Gemfile in the root of the directory containing the associated code. For
instance, in a Rails application, place the Gemfile in the same directory as the Rakefile.
SYNTAX
A Gemfile is evaluated as Ruby code, in a context which makes available a number of
methods used to describe the gem requirements.
GLOBAL SOURCES
At the top of the Gemfile, add a line for the Rubygems source that contains the gems
listed in the Gemfile.
source "https://rubygems.org"
It is possible, but not recommended as of Bundler 1.7, to add multiple global source
lines. Each of these sources MUST be a valid Rubygems repository.
Sources are checked for gems following the heuristics described in SOURCE PRIORITY. If a
gem is found in more than one global source, Bundler will print a warning after installing
the gem indicating which source was used, and listing the other sources where the gem is
available. A specific source can be selected for gems that need to use a non-standard
repository, suppressing this warning, by using the :source option or a source block.
CREDENTIALS
Some gem sources require a username and password. Use [bundle config(1)][bundle-config] to
set the username and password for any of the sources that need it. The command must be run
once on each computer that will install the Gemfile, but this keeps the credentials from
being stored in plain text in version control.
bundle config gems.example.com user:password
For some sources, like a company Gemfury account, it may be easier to include the
credentials in the Gemfile as part of the source URL.
source "https://user:password@gems.example.com"
Credentials in the source URL will take precedence over credentials set using config.
RUBY
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.
VERSION (required)
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.
ruby "1.9.3"
ENGINE
Each application may specify a Ruby engine. If an engine is specified, an engine version
must also be specified.
What exactly is an Engine? - A Ruby engine is an implementation of the Ruby language.
• For background: the reference or original implementation of the Ruby programming
language is called Matz´s Ruby Interpreter https://en.wikipedia.org/wiki/Ruby_MRI, or
MRI for short. This is named after Ruby creator Yukihiro Matsumoto, also known as
Matz. MRI is also known as CRuby, because it is written in C. MRI is the most widely
used Ruby engine.
• Other implementations https://www.ruby-lang.org/en/about/ of Ruby exist. Some of the
more well-known implementations include Rubinius https://rubinius.com/, and JRuby
http://jruby.org/. Rubinius is an alternative implementation of Ruby written in Ruby.
JRuby is an implementation of Ruby on the JVM, short for Java Virtual Machine.
ENGINE VERSION
Each application may specify a Ruby engine version. If an engine version 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"
PATCHLEVEL
Each application may specify a Ruby patchlevel.
ruby "2.0.0", :patchlevel => "247"
GEMS
Specify gem requirements using the gem method, with the following arguments. All
parameters are OPTIONAL unless otherwise specified.
NAME (required)
For each gem requirement, list a single gem line.
gem "nokogiri"
VERSION
Each gem MAY have one or more version specifiers.
gem "nokogiri", ">= 1.4.2"
gem "RedCloth", ">= 4.1.0", "< 4.2.0"
REQUIRE AS
Each gem MAY specify files that should be used when autorequiring via Bundler.require. You
may pass an array with multiple files or true if file you want required has same name as
gem or false to prevent any file from being autorequired.
gem "redis", :require => ["redis/connection/hiredis", "redis"]
gem "webmock", :require => false
gem "debugger", :require => true
The argument defaults to the name of the gem. For example, these are identical:
gem "nokogiri"
gem "nokogiri", :require => "nokogiri"
gem "nokogiri", :require => true
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 group.
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 the _default_ group
Bundler.require(:default) # identical
Bundler.require(:default, :test) # requires the _default_ and _test_ groups
Bundler.require(:test) # requires the _test_ group
The Bundler CLI allows you to specify a list of groups whose gems bundle install should
not install with the --without option. To specify multiple groups to ignore, specify a
list of groups separated by spaces.
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 it.
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 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 versions of the same gems in different groups. For more
details, see Understanding Bundler http://bundler.io/rationale.html.
PLATFORMS
If a gem should only be used in a particular platform or set of platforms, 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
mri Same as ruby, but not Rubinius
mingw Windows 32 bit ´mingw32´ platform (aka RubyInstaller)
x64_mingw
Windows 64 bit ´mingw32´ platform (aka RubyInstaller x64)
rbx Same as ruby, but only Rubinius (not MRI)
jruby JRuby
mswin Windows
You can restrict further by platform and version for all platforms except for rbx, jruby,
and mswin.
To specify a version in addition to a platform, append the version number without the
delimiter to the platform. For example, to specify that a gem should only be used on
platforms with Ruby 2.3, use:
ruby_23
The full list of platforms and supported versions includes:
ruby 1.8, 1.9, 2.0, 2.1, 2.2, 2.3, 2.4, 2.5
mri 1.8, 1.9, 2.0, 2.1, 2.2, 2.3, 2.4, 2.5
mingw 1.8, 1.9, 2.0, 2.1, 2.2, 2.3, 2.4, 2.5
x64_mingw
2.0, 2.1, 2.2, 2.3, 2.4, 2.5
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.
SOURCE
You can select an alternate Rubygems repository for a gem using the ´:source´ option.
gem "some_internal_gem", :source => "https://gems.example.com"
This forces the gem to be loaded from this source and ignores any global sources declared
at the top level of the file. If the gem does not exist in this source, it will not be
installed.
Bundler will search for child dependencies of this gem by first looking in the source
selected for the parent, but if they are not found there, it will fall back on global
sources using the ordering described in SOURCE PRIORITY.
Selecting a specific source repository this way also suppresses the ambiguous gem warning
described above in GLOBAL SOURCES (#source).
GIT
If necessary, you can specify that a gem is located at a particular git repository using
the :git parameter. The repository can be accessed via several protocols:
HTTP(S)
gem "rails", :git => "https://github.com/rails/rails.git"
SSH gem "rails", :git => "git@github.com:rails/rails.git"
git gem "rails", :git => "git://github.com/rails/rails.git"
If using SSH, the user that you use to run bundle install MUST have the appropriate keys
available in their $HOME/.ssh.
NOTE: http:// and git:// URLs should be avoided if at all possible. These protocols are
unauthenticated, so a man-in-the-middle attacker can deliver malicious code and compromise
your system. HTTPS and SSH are strongly preferred.
The group, platforms, and require options are available and behave exactly the same as
they would for a normal gem.
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.
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 properly 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 => "https://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 version 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"
For example:
git "https://github.com/rails/rails.git", :branch => "5-0-stable" do
git "https://github.com/rails/rails.git", :tag => "v5.0.0" do
git "https://github.com/rails/rails.git", :ref => "4aded" do
submodules
For reference, a git submodule https://git-scm.com/book/en/v2/Git-Tools-Submodules
lets you have another git repository within a subfolder of your repository. Specify
:submodules => true to cause bundler to expand any submodules included in the git
repository
If a git repository contains multiple .gemspecs, each .gemspec represents a gem located at
the same place in the file system as the .gemspec.
|~rails [git root]
| |-rails.gemspec [rails gem located here]
|~actionpack
| |-actionpack.gemspec [actionpack gem located here]
|~activesupport
| |-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.
GIT SOURCE
A custom git source can be defined via the git_source method. Provide the source´s name as
an argument, and a block which receives a single argument and interpolates it into a
string to return the full repo address:
git_source(:stash){ |repo_name| "https://stash.corp.acme.pl/#{repo_name}.git" }
gem ´rails´, :stash => ´forks/rails´
In addition, if you wish to choose a specific branch:
gem "rails", :stash => "forks/rails", :branch => "branch_name"
GITHUB
NOTE: This shorthand should be avoided until Bundler 2.0, since it currently expands to an
insecure git:// URL. This allows a man-in-the-middle attacker to compromise your system.
If the git repository you want to use is hosted on GitHub and is public, you can use the
:github shorthand to specify the github username and repository name (without the trailing
".git"), separated by a slash. If both the username and repository name are the same, you
can omit one.
gem "rails", :github => "rails/rails"
gem "rails", :github => "rails"
Are both equivalent to
gem "rails", :git => "git://github.com/rails/rails.git"
Since the github method is a specialization of git_source, it accepts a :branch named
argument.
GIST
If the git repository you want to use is hosted as a Github Gist and is public, you can
use the :gist shorthand to specify the gist identifier (without the trailing ".git").
gem "the_hatch", :gist => "4815162342"
Is equivalent to:
gem "the_hatch", :git => "https://gist.github.com/4815162342.git"
Since the gist method is a specialization of git_source, it accepts a :branch named
argument.
BITBUCKET
If the git repository you want to use is hosted on Bitbucket and is public, you can use
the :bitbucket shorthand to specify the bitbucket username and repository name (without
the trailing ".git"), separated by a slash. If both the username and repository name are
the same, you can omit one.
gem "rails", :bitbucket => "rails/rails"
gem "rails", :bitbucket => "rails"
Are both equivalent to
gem "rails", :git => "https://rails@bitbucket.org/rails/rails.git"
Since the bitbucket method is a specialization of git_source, it accepts a :branch named
argument.
PATH
You can specify that a gem is located in a particular location on the file system.
Relative paths are resolved relative to the directory containing 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 as paths.
gem "rails", :path => "vendor/rails"
If you would like to use multiple local gems directly from the filesystem, you can set a
global path option to the path containing the gem´s files. This will automatically load
gemspec files from subdirectories.
path ´components´ do
gem ´admin_ui´
gem ´public_ui´
end
BLOCK FORM OF SOURCE, GIT, PATH, GROUP and PLATFORMS
The :source, :git, :path, :group, and :platforms options may be applied to a group of gems
by using block form.
source "https://gems.example.com" do
gem "some_internal_gem"
gem "another_internal_gem"
end
git "https://github.com/rails/rails.git" do
gem "activesupport"
gem "actionpack"
end
platforms :ruby do
gem "ruby-debug"
gem "sqlite3"
end
group :development, :optional => true do
gem "wirble"
gem "faker"
end
In the case of the group block form the :optional option can be given to prevent a group
from being installed unless listed in the --with option given to the bundle install
command.
In the case of the git block form, the :ref, :branch, :tag, and :submodules options may be
passed to the git method, and all gems in the block will inherit those options.
INSTALL_IF
The install_if method allows gems to be installed based on a proc or lambda. This is
especially useful for optional gems that can only be used if certain software is installed
or some other conditions are met.
install_if -> { RUBY_PLATFORM =~ /darwin/ } do
gem "pasteboard"
end
GEMSPEC
The .gemspec http://guides.rubygems.org/specification-reference/ file is where you provide
metadata about your gem to Rubygems. Some required Gemspec attributes include the name,
description, and homepage of your gem. This is also where you specify the dependencies
your gem needs to run.
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 dependencies 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 requirement 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, :glob, :name, and :development_group options,
which control where bundler looks for the .gemspec, the glob it uses to look for the
gemspec (defaults to: "{,,/*}.gemspec"), what named .gemspec it uses (if more than one is
present), and which group development dependencies are included in.
When a gemspec dependency encounters version conflicts during resolution, the local
version under development will always be selected -- even if there are remote versions
that better match other requirements for the gemspec gem.
SOURCE PRIORITY
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 :source, :path, or :git)
2. For implicit gems (dependencies of explicit gems), any source, git, or path repository
declared on the parent. This results in bundler prioritizing the ActiveSupport gem
from the Rails git repository over ones from rubygems.org
3. The sources specified via global source lines, searching each source in your Gemfile
from last added to first added.
March 2018 GEMFILE(5)