Rails 4.2, Capistrano 3.4 local asset precompilation using rsync

assets.rake

# lib/capistrano/tasks/assets.rake
namespace :deploy do
  desc "Precompile assets locally and then rsync to web servers"
  task :compile_assets => [:set_rails_env] do

    run_locally do
      with rails_env: :production do
        execute "bundle exec rake assets:precompile"
      end
    end

    on release_roles(fetch(:assets_roles)) do |server|
      # Have to remove manifest files first because Sprockets reads the first manifest file it finds
      within release_path do
        with rails_env: fetch(:rails_env) do
          execute :rm, "./public/#{fetch(:assets_prefix)}/manifest-*"
        end
      end

      run_locally do
        execute "rsync -av ./public/#{fetch(:assets_prefix)}/ #{server.user}@#{server.hostname}:#{shared_path}/public/#{fetch(:assets_prefix)}/"
      end
    end

    run_locally do
      execute "rm -rf public/assets"
    end
  end

  desc "Cleanup expired assets"
  task :cleanup_assets => [:set_rails_env] do
    next unless fetch(:keep_assets)
    on release_roles(fetch(:assets_roles)) do
      within release_path do
        with rails_env: fetch(:rails_env) do
          execute :rake, "'assets:clean[#{fetch(:keep_assets)}]'"
        end
      end
    end
  end
  
  after :updated, "deploy:compile_assets"
  after "deploy:updated", "deploy:cleanup_assets"
  
  task :set_linked_dirs do
    set :linked_dirs, fetch(:linked_dirs, []).push("public/#{fetch(:assets_prefix)}")
  end
end

after "deploy:set_rails_env", "deploy:set_linked_dirs"

namespace :load do
  task :defaults do
    set :assets_roles, fetch(:assets_roles, [:web])
    set :assets_prefix, fetch(:assets_prefix, "assets")
  end
end

Revised this because it was leaving old manifest-md5hash.json files in production. Sprockets apparently reads the first such file it finds (by filename) and loads that version of the assets. So the production assets were getting pinned by the earlier hash fingerprint.

Also used the rake assets:clean task to remove old assets because we want to keep some around for cached views. Although that doesn't seem to be doing anything for me.

At this point, this really should include capinstrano's backup_manifest and restore_manifest tasks to safely handle deployment failure and not lose the manifest files if it rollsback deployment.