Speed up asset compilation by simply coping assets if nothing changed (based on git). Also works fine with turbo_sprockets. Load this with: load 'simple_assets' in your deploy.rb

simple_assets.rb

load 'deploy' unless defined?(_cset)

_cset :asset_env, "RAILS_GROUPS=assets"
_cset :assets_prefix, "assets"
_cset :assets_role, [:web]

_cset :normalize_asset_timestamps, false

after 'deploy:update_code', 'deploy:assets:precompile'

namespace :deploy do
  namespace :assets do
    desc <<-DESC
      Run the asset precompilation rake task. 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 "cd #{latest_release} && cp -a #{previous_release}/public/assets public/ && cp -a #{previous_release}/tmp/cache tmp/"
      updated_assets = capture("cd #{latest_release} && git show --pretty=format: --name-only #{previous_revision}..#{latest_revision} | grep -c ^app/assets/ || true").to_i
      if updated_assets > 0
        logger.info("#{updated_assets} updated assets. Will precompile.")
        run "cd #{latest_release} && #{rake} RAILS_ENV=#{rails_env} #{asset_env} assets:precompile"
      else
        logger.info("No updated assets, using assets from previous release.")
      end
    end

    desc <<-DESC
      Run the asset clean rake task. Use with caution, this will delete \
      all of your compiled assets. 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 :clean, :roles => assets_role, :except => { :no_release => true } do
      run "cd #{latest_release} && #{rake} RAILS_ENV=#{rails_env} #{asset_env} assets:clean"
    end
  end
end