Replaces deploy:assets:precompile task to do assets precompilation locally.

deploy.rb

# Base on http://stackoverflow.com/a/12839484/379604 and https://github.com/capistrano/capistrano/blob/master/lib/capistrano/recipes/deploy/assets.rb
namespace :deploy do
  namespace :assets do
    desc <<-DESC
      Run the asset precompilation rake task locally. You can specify the \
      full path to the rake executable by setting the rake variable. You \
      can also specify additional environment variables to pass to rake via \
      the asset_env variable. The defaults are:

        set :rake,      "rake"
        set :rails_env, "production"
        set :asset_env, "RAILS_GROUPS=assets"
    DESC
    task :precompile, :roles => assets_role, :except => { :no_release => true } do
      run_locally "#{rake} RAILS_ENV=#{rails_env.to_s.shellescape} #{asset_env} assets:precompile"
      run_locally "cd -- public && tar -zcvf #{assets_prefix}.tar.gz #{assets_prefix}"
      top.upload "public/#{assets_prefix}.tar.gz", "#{shared_path.shellescape}", :via => :scp
      run "cd -- #{shared_path.shellescape} && tar -zxvf #{assets_prefix}.tar.gz && rm -- #{assets_prefix}.tar.gz"
      run_locally "rm -- public/#{assets_prefix}.tar.gz && rm -rf -- public/#{assets_prefix}"
      run "cp -- #{shared_path.shellescape}/assets/manifest.yml #{current_release.shellescape}/assets_manifest.yml"
    end
  end
end