0. 环境

Puma + Mina + Rails 5.2 + Ubuntu 16.04

1. 期望

部署新代码期间网站依然可用，而不是卡 10-30 秒
发帖子前我谷歌查了半天依然搞不定，想看看大家的做法。
目前服务器我用的是 Puma。phased_restart 已经配置了
用了 mina-puma gem：https://github.com/untitledkingdom/mina-puma

mina puma:phased_restart

跑如上命令也毫无问题。结果如下图：

2. 实际结果

phased_restart 期间，网站有 10 秒 -30 秒不响应

3. 问题

大家是怎么做无缝部署的？（0 downtime deploy）
如果有人用 puma 实现过无缝部署，能分享下经验吗？

4. 贴 2 个文件

1. config/deploy.rb（Mina）
2. config/puma.rb（Puma 配置文件)

config/deploy.rb

require 'mina/rails'
require 'mina/git'
require 'mina/rvm'    # for rvm support. (https://rvm.io)
require 'mina/puma'  # https://github.com/untitledkingdom/mina-puma

set :application_name, '因隐私原因删除掉原有值'
set :domain, '因隐私原因删除掉原有值'
set :deploy_to, '因隐私原因删除掉原有值'
set :repository, '因隐私原因删除掉原有值'
set :branch, 'master'

set :user, 'ubuntu'          # Username in the server to SSH to.
set :port, '22'           # SSH port number.
set :forward_agent, true     # SSH forward_agent.

# For mina-puma
set :pumactl_socket, '/tmp/witt.sock'
set :puma_state, "/var/www/witticism.com/shared/tmp/sockets/puma.state"
set :puma_pid, "/var/www/witticism.com/shared/tmp/pids/puma.pid"

task :remote_environment do
  invoke :'rvm:use', 'ruby-2.4.1@default'
end

desc "Deploys the current version to the server."
task :deploy do
  deploy do
    invoke :'git:clone'
    invoke :'deploy:link_shared_paths'
    invoke :'bundle:install'
    invoke :'rails:db_migrate'
    invoke :'deploy:cleanup'

    on :launch do
      in_path(fetch(:current_path)) do
        command %{mkdir -p tmp/}
        command %{touch tmp/restart.txt}
      end
    end
  end
end

config/puma.rb

bind "unix:///tmp/witt.sock"

threads_count = Integer(ENV['RAILS_MAX_THREADS'] || 5)
threads threads_count, threads_count
environment ENV.fetch("RAILS_ENV") { "production" }

app_name = "witticism.com"
app_dir = File.expand_path("../..", __FILE__)
app_dir_parent = File.expand_path("../../", __FILE__)
application_path = "#{app_dir}"

pidfile "/var/www/witticism.com/shared/tmp/pids/puma.pid"
state_path "/var/www/witticism.com/shared/tmp/sockets/puma.state"

workers ENV.fetch("WEB_CONCURRENCY") { 2 }

before_fork do
  ActiveRecord::Base.connection_pool.disconnect! if defined?(ActiveRecord)
end

on_worker_boot do
  ActiveRecord::Base.establish_connection if defined?(ActiveRecord)
end