bundle-install(1) -- Install the dependencies specified in your Gemfile
=======================================================================

## SYNOPSIS

`bundle install` [--gemfile=GEMFILE]
                 [--path PATH] [--system]
                 [--without=GROUP1[ GROUP2...]]
                 [--local] [--deployment]
                 [--binstubs[=DIRECTORY]]
                 [--standalone[=GROUP1[ GROUP2...]]]
                 [--trust-policy=POLICY]
                 [--no-cache]
                 [--quiet]

## DESCRIPTION

Install the gems specified in your Gemfile(5). If this is the first
time you run bundle install (and a `Gemfile.lock` does not exist),
bundler will fetch all remote sources, resolve dependencies and
install all needed gems.

If a `Gemfile.lock` does exist, and you have not updated your Gemfile(5),
bundler will fetch all remote sources, but use the dependencies
specified in the `Gemfile.lock` instead of resolving dependencies.

If a `Gemfile.lock` does exist, and you have updated your Gemfile(5),
bundler will use the dependencies in the `Gemfile.lock` for all gems
that you did not update, but will re-resolve the dependencies of
gems that you did update. You can find more information about this
update process below under [CONSERVATIVE UPDATING][].

## OPTIONS

* `--gemfile=<gemfile>`:
  The location of the Gemfile(5) that bundler should use. This defaults
  to a gemfile in the current working directory. In general, bundler
  will assume that the location of the Gemfile(5) is also the project
  root, and will look for the `Gemfile.lock` and `vendor/cache` relative
  to it.

* `--path=<path>`:
  The location to install the gems in the bundle to. This defaults
  to the gem home, which is the location that `gem install` installs
  gems to. This means that, by default, gems installed without a
  `--path` setting will show up in `gem list`. This setting is a
  [remembered option][REMEMBERED OPTIONS].

* `--system`:
  Installs the gems in the bundle to the system location. This
  overrides any previous [remembered][REMEMBERED OPTIONS] use of
  `--path`.

* `--without=<list>`:
  A space-separated list of groups to skip installing. This is a
  [remembered option][REMEMBERED OPTIONS].

* `--local`:
  Do not attempt to connect to `rubygems.org`, instead using just
  the gems already present in Rubygems' cache or in `vendor/cache`.
  Note that if a more appropriate platform-specific gem exists on
  `rubygems.org`, it will not be found.

* `--deployment`:
  Switches bundler's defaults into [deployment mode][DEPLOYMENT MODE].
  Do not use this flag on development machines.

* `--binstubs[=<directory>]`:
  Create a directory (defaults to `bin`) containing an executable
  that runs in the context of the bundle. For instance, if the
  `rails` gem comes with a `rails` executable, this flag will create
  a `bin/rails` executable that ensures that all dependencies used
  come from the bundled gems.

* `--shebang ruby-install-name`:
  Uses the ruby executable (usually `ruby`) provided to execute the scripts created
  with --binstubs. For instance, if you use --binstubs with `--shebang jruby`,
  all executables will be created to use jruby instead.

* `--standalone[=<list>]`:
  Make a bundle that can work without Ruby Gems or Bundler at runtime.
  It takes a space separated list of groups to install. It creates a
  `bundle` directory and installs the bundle there. It also generates
  a `bundle/bundler/setup.rb` file to replace Bundler's own setup.

* `--trust-policy=[<policy>]`:
  Apply the Rubygems security policy named <policy>, where policy is one of
  HighSecurity, MediumSecurity, LowSecurity, or NoSecurity. For more detail,
  see the Rubygems signing documentation, linked below in [SEE ALSO][].

* `--no-cache`:
  Do not update the cache in `vendor/cache` with the newly bundled gems. This
  does not remove any existing cached gems, only stops the newly bundled gems
  from being cached during the install.

* `--quiet`:
  Do not print progress information to stdout. Instead, communicate the
  success of the install operation via exit status code.

## DEPLOYMENT MODE

Bundler's defaults are optimized for development. To switch to
defaults optimized for deployment, use the `--deployment` flag.
Do not activate deployment mode on development machines, as it
will cause in an error when the Gemfile is modified.

1. A `Gemfile.lock` is required.

   To ensure that the same versions of the gems you developed with
   and tested with are also used in deployments, a `Gemfile.lock`
   is required.

   This is mainly to ensure that you remember to check your
   `Gemfile.lock` into version control.

2. The `Gemfile.lock` must be up to date

   In development, you can modify your Gemfile(5) and re-run
   `bundle install` to [conservatively update][CONSERVATIVE UPDATING]
   your `Gemfile.lock` snapshot.

   In deployment, your `Gemfile.lock` should be up-to-date with
   changes made in your Gemfile(5).

3. Gems are installed to `vendor/bundle` not your default system location

   In development, it's convenient to share the gems used in your
   application with other applications and other scripts run on
   the system.

   In deployment, isolation is a more important default. In addition,
   the user deploying the application may not have permission to install
   gems to the system, or the web server may not have permission to
   read them.

   As a result, `bundle install --deployment` installs gems to
   the `vendor/bundle` directory in the application. This may be
   overridden using the `--path` option.

## SUDO USAGE

By default, bundler installs gems to the same location as `gem install`.

In some cases, that location may not be writable by your Unix user. In
that case, bundler will stage everything in a temporary directory,
then ask you for your `sudo` password in order to copy the gems into
their system location.

From your perspective, this is identical to installing them gems
directly into the system.

You should never use `sudo bundle install`. This is because several
other steps in `bundle install` must be performed as the current user:

* Updating your `Gemfile.lock`
* Updating your `vendor/cache`, if necessary
* Checking out private git repositories using your user's SSH keys

Of these three, the first two could theoretically be performed by
`chown`ing the resulting files to `$SUDO_USER`. The third, however,
can only be performed by actually invoking the `git` command as
the current user. Therefore, git gems are downloaded and installed
into `~/.bundle` rather than $GEM_HOME or $BUNDLE_PATH.

As a result, you should run `bundle install` as the current user,
and bundler will ask for your password if it is needed to put the
gems into their final location.

## INSTALLING GROUPS

By default, `bundle install` will install all gems in all groups
in your Gemfile(5), except those declared for a different platform.

However, you can explicitly tell bundler to skip installing
certain groups with the `--without` option. This option takes
a space-separated list of groups.

While the `--without` option will skip _installing_ the gems in the
specified groups, it will still _download_ those gems and use them to
resolve the dependencies of every gem in your Gemfile(5).

This is so that installing a different set of groups on another
 machine (such as a production server) will not change the
gems and versions that you have already developed and tested against.

`Bundler offers a rock-solid guarantee that the third-party
code you are running in development and testing is also the
third-party code you are running in production. You can choose
to exclude some of that code in different environments, but you
will never be caught flat-footed by different versions of
third-party code being used in different environments.`

For a simple illustration, consider the following Gemfile(5):

    source "https://rubygems.org"

    gem "sinatra"

    group :production do
      gem "rack-perftools-profiler"
    end

In this case, `sinatra` depends on any version of Rack (`>= 1.0`, while
`rack-perftools-profiler` depends on 1.x (`~> 1.0`).

When you run `bundle install --without production` in development, we
look at the dependencies of `rack-perftools-profiler` as well. That way,
you do not spend all your time developing against Rack 2.0, using new
APIs unavailable in Rack 1.x, only to have bundler switch to Rack 1.2
when the `production` group _is_ used.

This should not cause any problems in practice, because we do not
attempt to `install` the gems in the excluded groups, and only evaluate
as part of the dependency resolution process.

This also means that you cannot include different versions of the same
gem in different groups, because doing so would result in different
sets of dependencies used in development and production. Because of
the vagaries of the dependency resolution process, this usually
affects more than just the gems you list in your Gemfile(5), and can
(surprisingly) radically change the gems you are using.

## REMEMBERED OPTIONS

Some options (marked above in the [OPTIONS][] section) are remembered
between calls to `bundle install`, and by the Bundler runtime.

For instance, if you run `bundle install --without test`, a subsequent
call to `bundle install` that does not include a `--without` flag will
remember your previous choice.

In addition, a call to `Bundler.setup` will not attempt to make the
gems in those groups available on the Ruby load path, as they were
not installed.

The settings that are remembered are:

* `--deployment`:
  At runtime, this remembered setting will also result in Bundler
  raising an exception if the `Gemfile.lock` is out of date.

* `--path`:
  Subsequent calls to `bundle install` will install gems to the
  directory originally passed to `--path`. The Bundler runtime
  will look for gems in that location. You can revert this
  option by running `bundle install --system`.

* `--binstubs`:
  Bundler will update the executables every subsequent call to
  `bundle install`.

* `--without`:
  As described above, Bundler will skip the gems specified by
  `--without` in subsequent calls to `bundle install`. The
  Bundler runtime will also not try to make the gems in the
  skipped groups available.

## THE GEMFILE.LOCK

When you run `bundle install`, Bundler will persist the full names
and versions of all gems that you used (including dependencies of
the gems specified in the Gemfile(5)) into a file called `Gemfile.lock`.

Bundler uses this file in all subsequent calls to `bundle install`,
which guarantees that you always use the same exact code, even
as your application moves across machines.

Because of the way dependency resolution works, even a
seemingly small change (for instance, an update to a point-release
of a dependency of a gem in your Gemfile(5)) can result in radically
different gems being needed to satisfy all dependencies.

As a result, you `SHOULD` check your `Gemfile.lock` into version
control. If you do not, every machine that checks out your
repository (including your production server) will resolve all
dependencies again, which will result in different versions of
third-party code being used if `any` of the gems in the Gemfile(5)
or any of their dependencies have been updated.

## CONSERVATIVE UPDATING

When you make a change to the Gemfile(5) and then run `bundle install`,
Bundler will update only the gems that you modified.

In other words, if a gem that you `did not modify` worked before
you called `bundle install`, it will continue to use the exact
same versions of all dependencies as it used before the update.

Let's take a look at an example. Here's your original Gemfile(5):

    source "https://rubygems.org"

    gem "actionpack", "2.3.8"
    gem "activemerchant"

In this case, both `actionpack` and `activemerchant` depend on
`activesupport`. The `actionpack` gem depends on `activesupport 2.3.8`
and `rack ~> 1.1.0`, while the `activemerchant` gem depends on
`activesupport >= 2.3.2`, `braintree >= 2.0.0`, and `builder >= 2.0.0`.

When the dependencies are first resolved, Bundler will select
`activesupport 2.3.8`, which satisfies the requirements of both
gems in your Gemfile(5).

Next, you modify your Gemfile(5) to:

    source "https://rubygems.org"

    gem "actionpack", "3.0.0.rc"
    gem "activemerchant"

The `actionpack 3.0.0.rc` gem has a number of new dependencies,
and updates the `activesupport` dependency to `= 3.0.0.rc` and
the `rack` dependency to `~> 1.2.1`.

When you run `bundle install`, Bundler notices that you changed
the `actionpack` gem, but not the `activemerchant` gem. It
evaluates the gems currently being used to satisfy its requirements:

  * `activesupport 2.3.8`:
    also used to satisfy a dependency in `activemerchant`,
    which is not being updated
  * `rack ~> 1.1.0`:
    not currently being used to satify another dependency

Because you did not explicitly ask to update `activemerchant`,
you would not expect it to suddenly stop working after updating
`actionpack`. However, satisfying the new `activesupport 3.0.0.rc`
dependency of actionpack requires updating one of its dependencies.

Even though `activemerchant` declares a very loose dependency
that theoretically matches `activesupport 3.0.0.rc`, bundler treats
gems in your Gemfile(5) that have not changed as an atomic unit
together with their dependencies. In this case, the `activemerchant`
dependency is treated as `activemerchant 1.7.1 + activesupport 2.3.8`,
so `bundle install` will report that it cannot update `actionpack`.

To explicitly update `actionpack`, including its dependencies
which other gems in the Gemfile(5) still depend on, run
`bundle update actionpack` (see `bundle update(1)`).

`Summary`: In general, after making a change to the Gemfile(5) , you
should first try to run `bundle install`, which will guarantee that no
other gems in the Gemfile(5) are impacted by the change. If that
does not work, run [bundle update(1)][bundle-update].

## SEE ALSO

* Gem install docs: http://docs.rubygems.org/read/chapter/2
* Rubygems signing docs: http://docs.rubygems.org/read/chapter/21
