Guardfile DSL Configuring Guard

Cezary Baginski edited this page May 19, 2016 · 8 revisions

The Guardfile DSL is evaluated as plain Ruby, so you can use normal Ruby code in your Guardfile (and your ~/.guard.rb file which is evaluated first if it exists).

Guard itself provides the following DSL methods that can be used for configuration:


  • guard - to define and configure plugins
  • watch - to setup patterns matching relevant files
  • group - to organize plugins into groups
  • scope - to set the default groups or plugins to activate
  • directories - to tell Guard which directories to watch
  • clearing - whether Guard should clear the screen
  • notification - whether Guard should use notifications (popups, etc.)
  • interactor - whether guard should start the Pry console
  • callback - to setup extra actions inside hooks for a plugin
  • ignore - to ignore changes to irrelevant files
  • filter - to ignore changes to irrelevant files
  • logger - to enable/configure the logger


The guard method allows you to add a Guard plugin to your toolchain and configure it by passing the options after the name of the plugin:

guard :coffeescript, input: 'coffeescripts', output: 'javascripts'

You can define the same plugin more than once:

guard :coffeescript, input: 'coffeescripts', output: 'javascripts'
guard :coffeescript, input: 'specs', output: 'specs'

There is also a :first_match option, which runs the plugin only for the first matching watch expression, e.g.

guard :rspec, first_match: true do
  watch(/^spec/integration/(.*)_spec.rb$/) { "spec/integration" }

In this case, any file matching the first rule won't be matched by the second rule.


The watch method allows you to define which files are watched by a Guard

The watch method tells Guard which changed files the plugin should respond to:

guard :bundler do

This means: "out of all the files that get modified, added and removed, only let the file Gemfile (all file paths are relative to the current directory) be handled by this plugin ('bundler' in this case)".

String watch patterns are matched with String#==. You can also pass a regular expression to the watch method:

guard :jessie do

This instructs the jessie plugin to watch for file changes in the spec folder, but only for file names that ends with _spec or Spec and have a file type of js or coffee.

You can easily test your watcher regular expressions with Rubular.

When you add a block to the watch expression, you can modify the file name that has been detected before sending it to the plugin for processing:

guard :rspec do
  watch(%r{^lib/(.+)\.rb$}) { |m| "spec/lib/#{m[1]}_spec.rb" }

In this example the regular expression capture group (.+) is used to transform a file change in the lib folder to its test case in the spec folder. Regular expression watch patterns are matched with Regexp#match.

Since Guard 2.14.x, you can also use named group captures, e.g.

guard :rspec do
  watch(%r{^lib/(?<path>.+)\.rb$}) { |m| "spec/lib/#{m[:path]}_spec.rb" }

since m[:path] is more readable than having numbers m[1] or m[2].

And, since Guard 2.14.x, you can pass custom matchers, e.g.

only_uncommitted_lib_files =
watch(only_uncommitted_lib_files) { |m| "spec/#{m[:path_without_ext]}_spec.rb" }

And example should be here:

You can also launch any arbitrary command in the supplied block:

guard :shell do
  watch(/.*/) { `git status` }

NOTE: Normally, most plugins expect the block to return a path or array of paths - i.e. other plugins would think the git status output here is a file path (which would cause an error), so this trick of returning the command output only works for guard-shell plugin and other plugins that support arbitrary results.

You can also define watches outside of a guard plugin. This is useful to perform arbitrary Ruby logic (i.e. something project-specific).

watch(/.*/) { |m| puts "#{m[0]} changed." }


The group method allows you to group several plugins together. This comes in handy especially when you have a huge Guardfile and want to focus your development on a certain part.

group :specs do
  guard :rspec do

group :docs do
  guard :ronn do

Groups can be nested, reopened and can take multiple names to assign its plugin to multiple groups:

group :desktop do
  guard 'livereload' do

  group :mobile do
    guard 'livereload' do

group :mobile, :desktop do
  guard 'livereload' do

Groups to be run can be specified with the Guard DSL option --group (or -g):

$ bundle exec guard -g specs

Plugins that don't belong to a group are part of the default group.

Another neat use of groups is to group dependent plugins and stop processing if one fails. In order to make this work, the group needs to have the halt_on_fail option enabled and the Guard plugin needs to throw :task_has_failed to indicate that the action was not successful.

group :specs, halt_on_fail: true do
  guard :rspec do

  guard :cucumber do


The scope method allows you to define the default plugin or group scope for Guard, if not specified as command line option. Thus command line group and plugin scope takes precedence over the DSL scope configuration.

You can define either a single plugin or group:

scope plugin: :rspec
scope group: :docs

or specify multiple plugins or groups.

scope plugins: [:test, :jasmine]
scope groups: [:docs, :frontend]

If you define both the plugin and group scope, the plugin scope has precedence. If you use both the plural and the singular option, the plural has precedence.

Please be sure to call the scope method after you've declared your Guard plugins!


This option limits the directories watch to those given, which can improve responsiveness, performance and help reduce resource usage (CPU, memory) on larger projects.

directories %w(app config lib spec features)

Note: The --watchdir option overrides this. (see --watchdir above for extra info).

Note: Since recursion cannot be disabled on OSX, all other backends were made recursive - so if you want to watch selected directories AND files in the root directory of your project, move them to another directory and create symlinks back, e.g.

mkdir config
mv Gemfile config
ln -s config/Gemfile Gemfile


Guard can clear the screen before every action (which some people prefer).

The this clearing behavior can be set to :on or :off:

clearing :on

NOTE: since clearing is more of a user setting, it's best to have each team member set this in their own ~/.guard.rb file (instead of the project Guardfile).


If you don't specify any notification configuration in your Guardfile, Guard goes through the list of available notifiers and enables all that are available. If you specify your preferred library, auto detection will not take place:

notification :growl

will select the growl gem for notifications. You can also set options for a notifier:

notification :growl, sticky: true

Each notifier has a slightly different set of supported options:

notification :growl, sticky: true, host: '', password: 'secret'
notification :gntp, sticky: true, host: '', password: 'secret'
notification :libnotify, timeout: 5, transient: true, append: false, urgency: :critical
notification :notifu, time: 5, nosound: true, xp: true
notification :emacs

It's possible to use more than one notifier. This allows you to configure different notifiers for different OS if your project is developed cross-platform or if you like to have local and remote notifications.

Notifications can also be turned off in the Guardfile, in addition to setting the environment variable GUARD_NOTIFY or using the cli switch -n:

notification :off

NOTE: since notification is more of a user setting, it's best to have each team member set this in their own ~/.guard.rb file (instead of the project Guardfile).


You can customize the Pry interactor history and RC file like:

interactor guard_rc: '~/.my_guard-rc', history_file: '~/.my_guard_history_file'

If you do not need the Pry interactions with Guard at all, you can turn it off:

interactor :off


The callback method allows you to execute arbitrary code before or after any of the start, stop, reload, run_all, run_on_changes, run_on_additions, run_on_modifications and run_on_removals Guard plugins method. You can even insert more hooks inside these methods.

guard :rspec do

  callback(:start_begin) { `mate .` }

Please see the hooks and callbacks page in the Guard wiki for more details.


The ignore method can be used to exclude files and directories from the set of files being watched. Let's say you have used the watch method to monitor a directory, but you are not interested in changes happening to images, you could use the ignore method to exclude them.

This comes in handy when you have large amounts of non-source data in you project. By default .rbx, .bundle, .DS_Store, .git, .hg ,.svn, bundle, log, tmp, vendor/bundle are ignored.

NOTE: this option mostly helps when irrelevant changes are triggering guard tasks (e.g. a task starts before the editor finished saving all the files). Also, while it can reduce CPU time and increase responsiveness when using polling, instead, using --watchdirs is recommended for such "tuning" (e.g. large projects)

Please note that method only accept regexps. See Listen README.

To append to the default ignored files and directories, use the ignore method:

ignore %r{^ignored/path/}, /public/

To replace any existing ignored files and directories, use the ignore! method:

ignore! /data/


Alias of the ignore method.


The logger method allows you to customize the Lumberjack log output to your needs by specifying one or more options like:

logger level:       :warn,
       template:    '[:severity - :time - :progname] :message',
       time_format: 'at %I:%M%p',
       only:        [:rspec, :jasmine, 'coffeescript'],
       except:      :jammit,
       device:      'guard.log'

Log :level option must be either :debug, :info, :warn or :error. If Guard is started in debug mode, the log level will be automatically set to :debug.

The :template option is a string which can have one or more of the following placeholders: :time, :severity, :progname, :pid, :unit_of_work_id and :message. A unit of work is assigned for each action Guard performs on multiple Guard plugin.

The :time_format option directives are the same as Time#strftime or can be :milliseconds

The :only and :except are either a string or a symbol, or an array of strings or symbols that matches the name of the Guard plugin name that sends the log message. They cannot be specified at the same time.

By default the logger uses $stderr as device, but you can override this by supplying the :device option and set either an IO stream or a filename.