一、配置unicorn

gem install ‘unicorn’ 或在rails项目中Gemfile添加gem ‘unicorn’，并在rails项目中创建文件config/unicorn.rb，并在里面添加：

pid_path = '/path/shared/tmp/pids/'

before_fork do |server, worker|
  old_pid = "#{pid_path}unicorn.pid.oldbin"

  if File.exists?(old_pid) && server.pid != old_pid
    begin
      Process.kill("QUIT", File.read(old_pid).to_i)
    rescue Errno::ENOENT, Errno::ESRCH
      puts "Send 'QUIT' signal to unicorn error!"
    end
  end
end

二、mina配置

require 'mina/bundler'
require 'mina/rails'
require 'mina/git'
# require 'mina/rbenv'  # for rbenv support. (http://rbenv.org)
# require 'mina/rvm'    # for rvm support. (http://rvm.io)
require 'mina/rvm'    # for rvm support. (http://rvm.io)

# Basic settings:
set :domain, '210.10.10.10'
set :user, 'username'
set :deploy_to, 'path'
set :repository, 'xxxxx.git'
set :branch, 'master'

# For system-wide RVM install.
#   set :rvm_path, '/usr/local/rvm/bin/rvm'

# Manually create these paths in shared/ (eg: shared/config/database.yml) in your server.
# They will be linked in the 'deploy:link_shared_paths' step.
set :shared_paths, ['config/database.yml', 'config/secrets.yml', 'log']
task :environment do
  invoke :'rvm:use[ruby-2.2.4@default]'
end

task :setup => :environment do
  queue! %[mkdir -p "#{deploy_to}/#{shared_path}/log"]
  queue! %[chmod g+rx,u+rwx "#{deploy_to}/#{shared_path}/log"]

  queue! %[mkdir -p "#{deploy_to}/#{shared_path}/config"]
  queue! %[chmod g+rx,u+rwx "#{deploy_to}/#{shared_path}/config"]

  queue! %[touch "#{deploy_to}/#{shared_path}/config/database.yml"]
  queue! %[touch "#{deploy_to}/#{shared_path}/config/secrets.yml"]
  queue  %[echo "-----> Be sure to edit '#{deploy_to}/#{shared_path}/config/database.yml' and 'secrets.yml'."]

  if repository
    repo_host = repository.split(%r{@|://}).last.split(%r{:|\/}).first
    repo_port = /:([0-9]+)/.match(repository) && /:([0-9]+)/.match(repository)[1] || '22'

    queue %[
      if ! ssh-keygen -H  -F #{repo_host} &>/dev/null; then
        ssh-keyscan -t rsa -p #{repo_port} -H #{repo_host} >> ~/.ssh/known_hosts
      fi
    ]
  end
end

desc "Deploys the current version to the server."
task :deploy => :environment do
  to :before_hook do
    # Put things to run locally before ssh
  end
  deploy do
    # Put things that will set up an empty directory into a fully set-up
    # instance of your project.
    invoke :'git:clone'
    invoke :'deploy:link_shared_paths'
    invoke :'bundle:install'
    invoke :'rails:db_migrate'
    invoke :'rails:assets_precompile'
    invoke :'deploy:cleanup'

    to :launch do
      invoke :'unicorn:restart'
    end
  end
end

namespace :unicorn do
  set :unicorn_pid, "#{deploy_to}/shared/tmp/pids/unicorn.pid"
  set :start_unicorn, %{
    cd #{deploy_to}/#{current_path} && bundle exec unicorn -D -E production -c config/unicorn.rb
  }

#                                                                    Start task
# ------------------------------------------------------------------------------
  desc "Start unicorn"
  task :start => :environment do
    queue 'echo "-----> Start Unicorn"'
    queue! start_unicorn
  end

#                                                                     Stop task
# ------------------------------------------------------------------------------
  desc "Stop unicorn"
  task :stop do
    queue 'echo "-----> Stop Unicorn"'
    queue! %{
      test -s "#{unicorn_pid}" && kill -QUIT `cat "#{unicorn_pid}"` && rm -rf "#{unicorn_pid}" && echo "Stop Ok" && exit 0
      echo >&2 "Not running"
    }
  end

#                                                                  Restart task
# ------------------------------------------------------------------------------
  desc "Restart unicorn using 'upgrade'"
  task :restart => :environment do
    invoke 'unicorn:stop'
    invoke 'unicorn:start'
  end
end

这样在使用mina deploy部署的时候就可以实现unicorn的无缝重启。