Capistrano 'reaper not found' - ruby-on-rails

Question

I'm new to deploying with Capistrano, and I'm trying the following:
deploy.rb:
set :application, "example.co.uk"
# If you aren't deploying to /u/apps/#{application} on the target
# servers (which is the default), you can specify the actual location
# via the :deploy_to variable:
set :deploy_to, "/home/example/#{application}"
# SCM Options
default_run_options[:pty] = true # Must be set for the password prompt from git to work
ssh_options[:forward_agent] = true # Agent forwarding keys
set :repository, "git#github.com:mongeese/example.git" # Your clone URL
set :scm, "git"
set :branch, "master"
set :deploy_via, :remote_cache
set :user, "james" # The server's user for deploys
role :app, "example.co.uk"
role :web, "example.co.uk"
role :db, "example.co.uk", :primary => true
set :use_sudo, false
I get the following output:
* executing `deploy:restart'
* executing "/home/example/example.co.uk/current/script/process/reaper"
servers: ["example.co.uk"]
[example.co.uk] executing command
** [out :: example.co.uk] sh: /home/example/example.co.uk/current/script/process/reaper: not found
command finished
The "james" user can sudo. If I take out :use_sudo, I get the following error:
* executing "sudo -p 'sudo password: ' -u app /home/example/example.co.uk/current/script/process/reaper"
servers: ["example.co.uk"]
[example.co.uk] executing command
** [out :: example.co.uk] sudo: unknown user: app
command finished
I'm obviously missing something completely, as Google only seems to turn up old results about this.

Answer 1

There must have been a problem with the recipes, the following override works fine:
set :application, "example.co.uk"
# If you aren't deploying to /u/apps/#{application} on the target
# servers (which is the default), you can specify the actual location
# via the :deploy_to variable:
set :deploy_to, "/home/example/#{application}"
# SCM Options
default_run_options[:pty] = true # Must be set for the password prompt from git to work
ssh_options[:forward_agent] = true # Agent forwarding keys
set :repository, "git#github.com:example/MyRepo.git" # Your clone URL
set :scm, "git"
set :branch, "master"
set :deploy_via, :remote_cache
set :user, "james" # The server's user for deploys
role :app, "example.co.uk"
role :web, "example.co.uk"
role :db, "example.co.uk", :primary => true
namespace :deploy do
desc "Restarting mod_rails with restart.txt"
task :restart, :roles => :app, :except => { :no_release => true } do
run "touch #{current_path}/tmp/restart.txt"
end
[:start, :stop].each do |t|
desc "#{t} task is a no-op with mod_rails"
task t, :roles => :app do ; end
end
end

Answer 2

For people who encounter the same issue, have a glance to :
http://capitate.rubyforge.org/recipes/deploy.html#deploy:restart
When calling the "cap deploy" command, "update" + "restart" in the "deploy" namespace are called.
Default behaviour for "restart" is to call the "script/process/reaper" script under the current path. In James's answer, "restart" is overridden with the below command :
run "touch #{current_path}/tmp/restart.txt"
For example, people using unicorn should process like :
#launch unicorn
task :start, roles: :app, except: { no_release: true } do
run "cd #{current_path} && bundle exec unicorn_rails -c config/unicorn.rb -E #{rails_env} -D"
end
#stop unicorn
task :stop, roles: :app, except: { no_release: true } do
run "kill -KILL -s QUIT `cat #{shared_path}/pids/unicorn.pid`"
end
#when calling "cap deploy", files will be updated with #update# task (default behaviour),
#then "restart" task will be called (overridden below)
task :restart, roles: :app, except: { no_release: true } do
stop
start
end
Hope my contribution will be helpful to someone...