Rake is a build tool; it's purpose to automate the repetative tasks that we as developers do as part of building and deploying a project. You might have used tools that have a similar purpose before (Make, Ant, Maven, phing, etc) when using other languages.
rake is a command-line tool that comes with the rake gem, it is often bundled with ruby distributions (e.g. ruby-build in homebrew).
A Rakefile is the file where a project defines what it's tasks are and the instructions for rake to execute in order to complete those tasks.
Many Ruby projects come with rake task integrations to help automating them.
Now is probably a good time to check if you have rake installed and if not then install it. Try running rake --version or gem list | grep rake and you'll see if you already have it. To install it there are a few options:
- Install the gem:
sudo gem install rake - Using homebrew:
brew install ruby-build
The Rakefile is a plain text file that usually sits in the root directory of your project. Its syntax looks a lot like ruby because it is ruby! Everything you can do in ruby can be part of your rake task execution.
Lets start with a simple example that just displays some messages. You can find this file at /exercises/rake/Rakefile.
desc "A Task to remind me of the date"
task :date do
puts 'The date today is: ' + Time.new.strftime('%d/%m/%y')
end
Technically the desc 'Some description here' part is optional but it's good practice. Especially if you want to help new users as they can use rake -T or rake --tasks to get a list of tasks with their descriptions. Try getting a list of tasks for our Rakefile using one of those commands then run the 'date' task with rake date.
By default the rake command looks for the file ./Rakefile but you can provide a path to an alternate Rakefile. This isn't common but we're using it in this exercise to keep the examples isolated from each other and easier to understand, try this: rake --rakefile lib/tasks/alternate_path_rakefile.rake date
- RuboCop to check code against style guidelines. Try
rake --rakefile lib/tasks/rubocop.rake stylethen have a read of the rake task file. - RSpec for running tests. Try
rake --rakefile lib/tasks/rspec.rake specand take a look at the rake file. - Cleaning out temporary files. Rake has a built-in helper for cleaning files called 'rake/clean', use
rake --rakefile lib/tasks/clean.rake cleanandrake --rakefile lib/tasks/clean.rake clobberto see them in action. - Regenerating data files to start from a known state.
- Building dependancies from sources; this may includes things like sass to css compliation as well as javascript contatination and minification.
- Task inter-dependancy and the 'default' task (also
rake -P) - Taking input via command-line arguments and environment variables
- Using the shell to run other command-line applications
- Managing a large number of tasks using namespaces
- Testing your rake tasks
- Scheduling rake tasks using cron
- What happens if you rely on something that doesn't exist within the context of your environment (e.g. :dev, :test, :production)