ruby--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 "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 bun-
       dle install should not install with the --without  option.  To  specify
       multiple  groups  to ignore, specify a list of groups separated by spa-
       ces.



	   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 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:

	      git  "https://github.com/rails/rails.git",  :branch => "5-0-sta-
	      ble" 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  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.






				  April 2019			    GEMFILE(5)