ruby/man/gemfile.5.txt

GEMFILE(5)							    GEMFILE(5)



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  associ-
       ated  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 con-
       tains 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 avail-
       able. 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.1.html  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, Rubinius or Truf-
       fleRuby, 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.

       o   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.

       o   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  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"



   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 argu-
       ments. 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 "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



   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  bun-
       dle install should not install with the without configuration.

       To  specify  multiple  groups to ignore, specify a list of groups sepa-
       rated by spaces.



	   bundle config set without test
	   bundle config set 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  ver-
       sions  of  the  same  gems  in  different groups. For more details, see
       Understanding Bundler https://bundler.io/rationale.html.

   PLATFORMS
       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), Rubinius or TruffleRuby, but NOT Windows

       mri    Same as ruby, but only C Ruby (MRI)

       mingw  Windows 32 bit 'mingw32' platform (aka RubyInstaller)

       x64_mingw
	      Windows 64 bit 'mingw32' platform (aka RubyInstaller x64)

       rbx    Rubinius

       jruby  JRuby

       truffleruby
	      TruffleRuby

       mswin  Windows

       You  can  restrict  further  by	platform and version for all platforms
       except for rbx, jruby, truffleruby and mswin.

       To specify a version in addition to a platform, append the version num-
       ber 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, 2.6

       mri    1.8, 1.9, 2.0, 2.1, 2.2, 2.3, 2.4, 2.5, 2.6

       mingw  1.8, 1.9, 2.0, 2.1, 2.2, 2.3, 2.4, 2.5, 2.6

       x64_mingw
	      2.0, 2.1, 2.2, 2.3, 2.4, 2.5, 2.6

       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	bundle-install.1.html,
       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).

       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.

   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 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 => "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 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". 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"

       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 reposi-
	      tory. Specify :submodules => true to cause bundler to expand any
	      submodules 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-
       spec.



	   |~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 cur-
       rently expands to an insecure git:// URL. This allows a man-in-the-mid-
       dle attacker to compromise your system.

       If the git repository you want to use is hosted on GitHub and  is  pub-
       lic,  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 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
       as paths.



	   gem "rails", :path => "vendor/rails"



       If you would like to use multiple local gems directly from the filesys-
       tem,  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 :sub-
       modules 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 rec-
       ommended that you also ensure all other gems in the Gemfile  are  using
       explicit  sources,  either  via	source blocks or :source directives on
       individual gems.

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 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, :glob, :name, and :develop-
       ment_group options, which control where bundler looks for the .gemspec,
       the glob it uses to look for the  gemspec  (defaults  to:  "{,,/*}.gem-
       spec"),	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  resolu-
       tion,  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.






				 November 2019			    GEMFILE(5)