capistrano/lib/switchtower/recipes/standard.rb

# Standard tasks that are useful for most recipes. It makes a few assumptions:
# 
# * The :app role has been defined as the set of machines consisting of the
#   application servers.
# * The :web role has been defined as the set of machines consisting of the
#   web servers.
# * The Rails spinner and reaper scripts are being used to manage the FCGI
#   processes.
# * There is a script in script/ called "reap" that restarts the FCGI processes

desc "Enumerate and describe every available task."
task :show_tasks do
  keys = tasks.keys.sort_by { |a| a.to_s }
  longest = keys.inject(0) { |len,key| key.to_s.length > len ? key.to_s.length : len } + 2

  puts "Available tasks"
  puts "---------------"
  tasks.keys.sort_by { |a| a.to_s }.each do |key|
    desc = (tasks[key].options[:desc] || "").strip.split(/\r?\n/)
    puts "%-#{longest}s %s" % [key, desc.shift]
    puts "%#{longest}s %s" % ["", desc.shift] until desc.empty?
    puts
  end
end

desc "Set up the expected application directory structure on all boxes"
task :setup do
  run <<-CMD
    mkdir -p -m 775 #{releases_path} #{shared_path}/system &&
    mkdir -p -m 777 #{shared_path}/log
  CMD
end

desc <<DESC
Disable the web server by writing a "maintenance.html" file to the web
servers. The servers must be configured to detect the presence of this file,
and if it is present, always display it instead of performing the request.
DESC
task :disable_web, :roles => :web do
  on_rollback { delete "#{shared_path}/system/maintenance.html" }

  maintenance = render("maintenance", :deadline => ENV['UNTIL'],
    :reason => ENV['REASON'])
  put maintenance, "#{shared_path}/system/maintenance.html", :mode => 0644
end

desc %(Re-enable the web server by deleting any "maintenance.html" file.)
task :enable_web, :roles => :web do
  delete "#{shared_path}/system/maintenance.html"
end

desc <<DESC
Update all servers with the latest release of the source code. All this does
is do a checkout (as defined by the selected scm module).
DESC
task :update_code do
  on_rollback { delete release_path, :recursive => true }

  source.checkout(self)

  run <<-CMD
    rm -rf #{release_path}/log #{release_path}/public/system &&
    ln -nfs #{shared_path}/log #{release_path}/log &&
    ln -nfs #{shared_path}/system #{release_path}/public/system
  CMD
end

desc <<DESC
Rollback the latest checked-out version to the previous one by fixing the
symlinks and deleting the current release from all servers.
DESC
task :rollback_code do
  if releases.length < 2
    raise "could not rollback the code because there is no previous version"
  else
    run <<-CMD
      ln -nfs #{previous_release} #{current_path} &&
      rm -rf #{current_release}
    CMD
  end
end

desc <<DESC
Update the 'current' symlink to point to the latest version of
the application's code.
DESC
task :symlink do
  on_rollback { run "ln -nfs #{previous_release} #{current_path}" }
  run "ln -nfs #{current_release} #{current_path}"
end

desc "Restart the FCGI processes on the app server."
task :restart, :roles => :app do
  sudo "#{current_path}/script/reap"
end

desc <<DESC
Run the migrate task in the version of the app indicated by the 'current'
symlink. This means you should not invoke this task until the symlink has
been updated to the most recent version.
DESC
task :migrate, :roles => :db, :only => { :primary => true } do
  run "cd #{current_path} && rake RAILS_ENV=production migrate"
end

desc <<DESC
A macro-task that updates the code, fixes the symlink, and restarts the
application servers.
DESC
task :deploy do
  transaction do
    update_code
    symlink
  end

  restart
end

desc "A macro-task that rolls back the code and restarts the application servers."
task :rollback do
  rollback_code
  restart
end