Gemfile - A format for describing gem dependencies for Ruby programs
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.
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 a single line for the RubyGems source that
contains the gems listed in the Gemfile.
source "https://rubygems.org"
You can add only one global source. In Bundler 1.13, adding multiple global
sources was deprecated. The source MUST be a valid RubyGems repository.
To use more than one source of RubyGems, you should use source block
.
A source is checked for gems following the heuristics described in SOURCE PRIORITY.
Note about a behavior of the feature deprecated in Bundler 1.13:
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 source block.
Some gem sources require a username and password. Use bundle config(1) 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.
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, TruffleRuby, etc., this should be the Ruby version that the engine is compatible with.
ruby "3.1.2"
If you wish to derive your Ruby version from a version file (ie .ruby-version),
you can use the file option instead.
ruby file: ".ruby-version"
The version file should conform to any of the following formats:
3.1.2 (.ruby-version)ruby 3.1.2 (.tool-versions, read: https://asdf-vm.com/manage/configuration.html#tool-versions)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, 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 of Ruby exist. Some of the more well-known implementations include JRuby and TruffleRuby. Rubinius is an alternative implementation of Ruby written in Ruby. JRuby is an implementation of Ruby on the JVM, short for Java Virtual Machine. TruffleRuby is a Ruby implementation on the GraalVM, a language toolkit built on the JVM.
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 "2.6.8", engine: "jruby", engine_version: "9.3.8.0"
Each application may specify a Ruby patchlevel. Specifying the patchlevel has been meaningless since Ruby 2.1.0 was released as the patchlevel is now uniquely determined by a combination of major, minor, and teeny version numbers.
This option was implemented in Bundler 1.4.0 for Ruby 2.0 or earlier.
ruby "3.1.2", patchlevel: "20"
Specify gem requirements using the gem method, with the following arguments.
All parameters are OPTIONAL unless otherwise specified.
For each gem requirement, list a single gem line.
gem "nokogiri"
Each gem MAY have one or more version specifiers.
gem "nokogiri", ">= 1.4.2"
gem "RedCloth", ">= 4.1.0", "< 4.2.0"
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 the file
you want required has the 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 "byebug", 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
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 configuration.
To specify multiple groups to ignore, specify a list of groups separated by spaces.
bundle config set --local without test
bundle config set --local without development test
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.
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:
rubymriwindowsmswinmswin64rbxjrubytrufflerubyOn platforms ruby, mri, mswin, mswin64, and windows, you may
additionally specify a version by appending the major and minor version numbers
without a delimiter. For example, to specify that a gem should only be used on
platform ruby version 3.1, use:
ruby_31
As with groups (above), you may specify one or more platforms:
gem "weakling", platforms: :jruby
gem "ruby-debug", platforms: :mri_31
gem "nokogiri", platforms: [:windows_31, :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 you always want the pure ruby variant of a gem to be chosen over platform
specific variants, you can use the force_ruby_platform option:
gem "ffi", force_ruby_platform: true
This can be handy (assuming the pure ruby variant works fine) when:
required_ruby_version upper bound), but you still want your Gemfile{.lock}
files to resolve under that ruby.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 the global source 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 the global source.
Note about a behavior of the feature deprecated in Bundler 1.13: Selecting a specific source repository this way also suppresses the ambiguous gem warning described above in GLOBAL SOURCE.
Using the :source option for an individual gem will also make that source
available as a possible global source for any other gems which do not specify
explicit sources. Thus, when adding gems with explicit sources, it is
recommended that you also ensure all other gems in the Gemfile are using
explicit sources.
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)SSHgitIf 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
MUST only specify at most one of these options. The default
is branch: "master". For example:
gem "rails", git: "https://github.com/rails/rails.git", branch: "5-0-stable"
gem "rails", git: "https://github.com/rails/rails.git", tag: "v5.0.0"
gem "rails", git: "https://github.com/rails/rails.git", ref: "4aded"
submodulessubmodules: true to cause bundler to expand any
submodules included in the git repositoryIf 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.
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"
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: "https://github.com/rails/rails.git"
Since the github method is a specialization of git_source, it accepts a :branch named argument.
You can also directly pass a pull request URL:
gem "rails", github: "https://github.com/rails/rails/pull/43753"
Which is equivalent to:
gem "rails", github: "rails/rails", branch: "refs/pull/43753/head"
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.
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.
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
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.
The presence of a source block in a Gemfile also makes that source
available as a possible global source for any other gems which do not specify
explicit sources. Thus, when defining source blocks, it is
recommended that you also ensure all other gems in the Gemfile are using
explicit sources, either via source blocks or :source directives on
individual gems.
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
The .gemspec 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.
When attempting to locate a gem to satisfy a gem requirement, bundler uses the following priority order:
:source, :path, or
:git)rubygems.org