Hello,
I seem to be confused about how to restart Unicorn when deploying updates to a
Rails app via Capistrano.
I just had a problem where a bundled gem wasn't being seen by the Unicorn
processes, even though app code I introduced at the same time was being served
by the Unicorn processes. I had restarted Unicorn numerous times using `bundle
exec cap deploy:restart` (see the code below), which I thought was the right
way to do zero-downtime restarts, but my problem was only solved by doing a
hard restart of Unicorn with `bundle exec cap deploy:hard_restart`.
With each "normal" restart I tailed the stderr log to check everything was ok;
everything appeared fine, with gems refreshed etc.
Please could somebody explain what I'm doing wrong with my normal restarts?
config/deploy.rb:
set :unicorn_config, "#{current_path}/config/unicorn.rb"
set :unicorn_pid, "#{shared_path}/pids/unicorn.pid"
namespace :deploy do
task :start, :roles => :app, :except => { :no_release => true } do
run "cd #{current_path} && #{sudo_workaround} bundle exec unicorn -c
#{unicorn_config} -E #{rails_env} -D"
end
task :stop, :roles => :app, :except => { :no_release => true } do
run "#{sudo_workaround} kill -s QUIT `cat #{unicorn_pid}`"
end
task :hard_stop, :roles => :app, :except => { :no_release => true } do
run "#{sudo_workaround} kill `cat #{unicorn_pid}`"
end
task :restart, :roles => :app, :except => { :no_release => true } do
run "#{sudo_workaround} kill -s USR2 `cat #{unicorn_pid}`"
end
task :hard_restart, :roles => :app, :except => { :no_release => true } do
hard_stop
start
end
end
# Works around Ubuntu changing the PATH when you use sudo.
# sudo's path can find common commands like echo but not much else.
def sudo_workaround
"sudo env PATH=$PATH"
end
config/unicorn.rb:
APP_PATH = '/var/www/apps/sparkle'
worker_processes 4
user 'rails', 'rails'
working_directory "#{APP_PATH}/current"
listen "/tmp/unicorn_sparkle.sock", :backlog => 64
timeout 30
pid "#{APP_PATH}/shared/pids/unicorn.pid"
stderr_path "#{APP_PATH}/shared/log/unicorn.stderr.log"
stdout_path "#{APP_PATH}/shared/log/unicorn.stdout.log"
preload_app true
GC.respond_to?(:copy_on_write_friendly=) and GC.copy_on_write_friendly =
true
before_fork do |server, worker|
defined?(ActiveRecord::Base) and ActiveRecord::Base.connection.disconnect!
old_pid = "#{server.config[:pid]}.oldbin"
if old_pid != server.pid
begin
sig = (worker.nr + 1) >= server.worker_processes ? :QUIT : :TTOU
Process.kill(sig, File.read(old_pid).to_i)
rescue Errno::ENOENT, Errno::ESRCH
end
end
end
after_fork do |server, worker|
defined?(ActiveRecord::Base) and ActiveRecord::Base.establish_connection
end
This is all with Unicorn 4.2.0 and Rails 3.0.11.
Many thanks in advance,
Andy Stewart
----
http://airbladesoftware.com
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