$ sudo adduser deploy
$ sudo adduser deploy sudo
$ visudo
# 将 sudo 用户改成运行 sudo 无需密码
% sudo   ALL=(ALL) NOPASSWD:ALL

## 切换到 deploy 用户
$ su deploy
$ mkdir .ssh
$ vim .ssh/authorized_keys
# 粘贴你的 ssh 公钥，然后保存

$ sudo apt-get update
$ sudo apt-get install git-core curl zlib1g-dev build-essential libssl-dev libreadline-dev
libyaml-dev libsqlite3-dev sqlite3 libxml2-dev libxslt1-dev libcurl4-openssl-dev
python-software-properties libffi-dev nodejs

$ cd
$ git clone https://github.com/rbenv/rbenv.git ~/.rbenv
$ echo 'export PATH="$HOME/.rbenv/bin:$PATH"' >> ~/.bashrc
$ echo 'eval "$(rbenv init -)"' >> ~/.bashrc
$ exec $SHELL

$ git clone https://github.com/rbenv/ruby-build.git ~/.rbenv/plugins/ruby-build
$ echo 'export PATH="$HOME/.rbenv/plugins/ruby-build/bin:$PATH"' >> ~/.bashrc
$ exec $SHELL

$ rbenv install 2.3.1
$ rbenv global 2.3.1
$ ruby -v
$ gem install bundler

$ sudo apt-key adv --keyserver hkp://keyserver.ubuntu.com:80 --recv-keys 561F9B9CAC40B2F7
$ sudo apt-get install -y apt-transport-https ca-certificates

# Add Passenger APT repository
$ sudo sh -c 'echo deb https://oss-binaries.phusionpassenger.com/apt/passenger trusty main > /etc/apt/sources.list.d/passenger.list'
$ sudo apt-get update
$ sudo apt-get install -y nginx

$ sudo vim /etc/nginx/nginx.conf
  # 这行取消注释
  include /etc/nginx/passenger.conf;

$ sudo vim /etc/nginx/passenger.conf
  passenger_root /usr/lib/ruby/vendor_ruby/phusion_passenger/locations.ini;
  passenger_ruby /home/deploy/.rbenv/shims/ruby; # 设置 Rbenv

$ sudo apt-get install postgresql postgresql-contrib libpq-dev
$ sudo su - postgres
$ vim /etc/postgresql/9.3/main/pg_hba.conf
local   all             all                           md5
$ service postgresql restart
# 新建 app_db_user 的数据库用户名，请牢记数据库密码，待会需要配置到 database.yml 里面去
$ createuser --interactive -P blog_db_user
# 新建 blog_production 数据库
$ createdb blog_production -Ublog_db_user
$ exit

$ cd ~
$ mkdir -p apps/blog/shared/config
$ cd apps/blog/shared/config
# 创建一些 application.yml database.yml secrets.yml

# 在服务器上生成公钥配置到项目的 deploy key 里面去
$ ssh-keygen
$ cat ~/.ssh/id_rsa.pub

group :development do
  gem 'capistrano', '~> 3.5'
  gem 'capistrano-rbenv', '~> 2.0'
  gem 'capistrano-bundler', '~> 1.1'
  gem 'capistrano-rails', '~> 1.1'
  gem 'capistrano-passenger', '~> 0.2'
  gem 'capistrano-sidekiq'
end

# Load DSL and set up stages
require "capistrano/setup"

# Include default deployment tasks
require "capistrano/deploy"

# Include tasks from other gems included in your Gemfile
# require 'capistrano/rvm'
# 因为使用的是 rbenv
require 'capistrano/rbenv'
# require 'capistrano/chruby'
require 'capistrano/bundler'
require 'capistrano/rails/assets'
require 'capistrano/rails/migrations'
require 'capistrano/passenger'
# 因为使用了 sidekiq，部署的时候会自动重启 sidekiq
require 'capistrano/sidekiq'

# 因为使用了 whenever，部署的时候会自动重新生成定时任务
require "whenever/capistrano"

# Load custom tasks from `lib/capistrano/tasks` if you have any defined
Dir.glob("lib/capistrano/tasks/*.rake").each { |r| import r }

# config valid only for current version of Capistrano
lock '3.5.0'

set :application, 'blog'
set :repo_url, 'git@github.com:grant/blog.git'

set :rbenv_type, :user # or :system, depends on your rbenv setup
set :rbenv_ruby, '2.3.1'

# Default branch is :master
ask :branch, `git rev-parse --abbrev-ref HEAD`.chomp

set :rails_env, 'production'

# 设置成代码的目录
set :deploy_to, '/home/deploy/apps/blog'

# Default value for :linked_files is []
set :linked_files, fetch(:linked_files, []).push('config/database.yml', 'config/secrets.yml', 'config/application.yml')

# Default value for linked_dirs is []
set :linked_dirs, fetch(:linked_dirs, []).push('log', 'private/sdf_files', 'vendor/bundle', 'tmp/pids', 'tmp/cache', 'tmp/sockets', 'public/system', 'public/uploads')

# Default value for keep_releases is 5
# set :keep_releases, 5
set :whenever_identifier, -> { "#{fetch(:application)}_#{fetch(:stage)}" }

# 下面是自动做 db:seed 在部署完成后
namespace :deploy do
  after :restart, :clear_cache do
    on roles(:web), in: :groups, limit: 3, wait: 10 do
      # Here we can do anything such as:
      within release_path do
        with rails_env: fetch(:rails_env) do
          execute :rake, 'db:seed'
        end
      end
    end
  end
end

server 'grantcss.com', user: 'deploy', roles: %w(web app db)

$ cap production deploy

# ssh deploy用户 登录到服务器
$ cd /etc/nginx/sites-available/
$ vim blog
server {
    listen 80;
    server_name blog.grantcss.com;
    passenger_enabled on;
    rails_env    production;
    root         /home/deploy/apps/blog/current/public;
}

$ sudo ln -s /etc/nginx/sites-available/blog /etc/nginx/sites-enabled/blog
$ sudo rm /etc/nginx/sites-enabled/default
$ sudo service nginx restart

gem "partitioned", github: "dkhofer/partitioned", branch: "rails-4-2"
gem 'activerecord-redshift-adapter',  github: "arp/activerecord-redshift-adapter", branch: "rails4-compatibility"

class PartitionedByCreatedAtMonthly < Partitioned::ByMonthlyTimeField
  self.abstract_class = true

  def self.partition_time_field
    :created_at
  end

  partitioned do |partition|
    partition.index :id, unique: true
  end
end

class DeviceLog < PartitionedByCreatedAtMonthly
end

class CreatePartitionedTables < ActiveRecord::Migration
  def up
    # 创建分区表专用的名字为 device_logs_partitions 的模式
    DeviceLog.create_infrastructure
    dates = DeviceLog.partition_generate_range(Date.today, Date.today + 5.year)
    DeviceLog.create_new_partition_tables(dates)
  end

  def down
    DeviceLog.delete_infrastructure
  end
end

### 假设是今天 20170731 号运行的
DeviceLog.create(:log => 'xxx')

INSERT INTO device_logs_partitions.p201607 (log,...) values ('xxx',...;

DeviceLog.from_partition(today).find(1)
DeviceLog.find(:first, conditions: {created_at:
  @select_date.beginning_of_day..@select_date.end_of_day})

Partitioned::ById
Partitioned::ByForeignKey
Partitioned::ByDailyTimeField
Partitioned::ByMonthlyTimeField
Partitioned::ByWeeklyTimeField
Partitioned::ByYearlyTimeField

group :development do
  gem 'listen', '~> 3.0.4'
end

# /etc/init/sidekiq.conf - Sidekiq config

# This example config should work with Ubuntu 12.04+.  It
# allows you to manage multiple Sidekiq instances with
# Upstart, Ubuntu's native service management tool.
#
# See workers.conf for how to manage all Sidekiq instances at once.
#
# Save this config as /etc/init/sidekiq.conf then mange sidekiq with:
#   sudo start sidekiq
#   sudo stop sidekiq
#   sudo status sidekiq
#
# or use the service command:
#   sudo service sidekiq {start,stop,restart,status}
#

description "Sidekiq Background Worker"

# This starts upon bootup and stops on shutdown
start on runlevel [2345]
stop on runlevel [06]

# change to match your deployment user
setuid deploy
setgid deploy
env HOME=/home/deploy

respawn
respawn limit 3 30

# TERM is sent by sidekiqctl when stopping sidekiq. Without declaring these as
# normal exit codes, it just respawns.
normal exit 0 TERM

#instance $index

script
# this script runs in /bin/sh by default
# respawn as bash so we can source in rbenv
exec /bin/bash <<'EOT'
  # Pick your poison :) Or none if you're using a system wide installed Ruby.
  # rbenv
  # source /home/apps/.bash_profile
  # OR
  # source /home/apps/.profile
  # OR system:
  # source /etc/profile.d/rbenv.sh
  #
  # rvm
  # source /home/apps/.rvm/scripts/rvm
  # Logs out to /var/log/upstart/sidekiq.log by default

  # 服务器上的数据库用户名和密码在这个文件里面
  source /etc/environment

  # 服务器用的是 rbenv
  export HOME=/home/deploy
  export PATH="$HOME/.rbenv/bin:$PATH"
  eval "$(rbenv init -)"
  export PATH="$HOME/.rbenv/plugins/ruby-build/bin:$PATH"

  cd /var/www/xxx_app/current
  exec bundle exec sidekiq -e production -P /var/www/xxx_app/current/tmp/pids/sidekiq.pid -L /var/www/xxx_app/current/log/sidekiq.log
EOT
end script

check process sidekiq_application_production with pidfile /var/www/xxx_app/shared/tmp/pids/sidekiq.pid
  start program = "/bin/bash -c 'sudo start sidekiq'"
  stop program = "/bin/bash -c 'sudo stop sidekiq'" with timeout 90 seconds
  if totalmem is greater than 500 MB for 2 cycles then restart # eating up memory?
  group sidekiq

class ForgottenPassword
  def initialize(user_id)
    user = User.find user_id
    mail = UserMailer.password_reset @user
    mail.deliver
  end
end

class ForgottenPasswordController
  def create
    begin
      ForgottenPassword.new(params[:user_id])
      # render the view
    rescue
      # Handle exceptions and render the view
    end
  end
end

> [3, 1, 4, 1, 5, 9, 2, 6, 5, 3, 5].chunk { |n| n.even? }.to_a
=> [[false, [3, 1]], [true, [4]], [false, [1, 5, 9]], [true, [2, 6]], [false, [5, 3, 5]]]

[3, 1, 4, 1, 5, 9, 2, 6, 5, 3, 5].chunk { |n| n > 5 || nil }.to_a
=> [[true, [9]], [true, [6]]]

[3, 1, 4, 1, 5, 9, 2, 6, 5, 3, 5].chunk { |n| n > 5 && nil }.to_a
=> [[false, [3, 1, 4, 1, 5]], [false, [2]], [false, [5, 3, 5]]]

[3, 1, 4, 1, 5, 9, 2, 6, 5, 3, 5].chunk { |n| n > 5 || :_separator }.to_a
=> [[true, [9]], [true, [6]]]

[3, 9, 10, 2, 6, 7].chunk { |n| n > 5 }.to_a
=> [[false, [3]], [true, [9, 10]], [false, [2]], [true, [6, 7]]]

[3, 9, 10, 2, 6, 7].chunk { |n| n > 5 ? :_alone : true }.to_a
=> [[true, [3]], [:_alone, [9]], [:_alone, [10]], [true, [2]], [:_alone, [6]], [:_alone, [7]]]

- @users = User.order('created_at desc')

%h1 User Monthly Breakdown

- @users.chunk { |u| u.created_at.strftime("%B %Y") }.each do |month, users|
  %h3= month
  %table.table
    %thead
      %tr
        %th Name
        %th Email

    - users.each do |user|
      %tr
        %td= user.name
        %td= user.email

(1..6).partition { |v| v.even? }  #=> [[2, 4, 6], [1, 3, 5]]

a = %w(albatross dog horse)
a.max                        #=> "horse"
a.max_by { |x| x.length }   #=> "albatross"
a.min_by { |x| x.length }   #=> "dog"
a.minmax_by { |x| x.length }   #=> ["dog", "albatross"]

a = [ 4, 5, 6 ]
b = [ 7, 8, 9 ]

[1, 2, 3].zip(a, b)      #=> [[1, 4, 7], [2, 5, 8], [3, 6, 9]]
[1, 2].zip(a, b)         #=> [[1, 4, 7], [2, 5, 8]]
a.zip([1, 2], [8])       #=> [[4, 1, 8], [5, 2, nil], [6, nil, nil]]

session[:current_user_id] = @user.id

app/controllers/sessions_controller.rb
def create
  # ...
  session[:current_user_id] = @user.id
  # ...
end

app/controllers/users_controller.rb

def index
  current_user = User.find_by_id(session[:current_user_id])
  # ...
end

$ curl -I http://www.google.com | grep Set-Cookie

Set-Cookie: NID=67=J2xeyegolV0SSneukSOANOCoeuDQs7G1FDAK2j-nVyaoejz-4K6aouUQtyp5B_rK3Z7G-EwTIzDm7XQ3_ZUVNnFmlGfIHMAnZQNd4kM89VLzCsM0fZnr_N8-idASAfBEdS; expires=Wed, 16-Sep-2015 05:44:42 GMT; path=/; domain=.google.com; HttpOnly

> GET / HTTP/1.1
> User-Agent: curl/7.37.1
> Host: www.google.com
> Accept: */*
> Cookie: NID=67=J2xeyegolV0SSneukSOANOCoeuDQs7G1FDAK2j-nVyaoejz-4K6aouUQtyp5B_rK3Z7G-EwTIzDm7XQ3_ZUVNnFmlGfIHMAnZQNd4kM89VLzCsM0fZnr_N8-idASAfBEdS; expires=Wed, 16-Sep-2015 05:44:42 GMT; path=/; domain=.google.com; HttpOnly

Cookie: _my_app_session=09497d46978bf6f32265fefb5cc52264;
path=/; HttpOnly

# app/controllers/users_controller.rb
class UsersController < ApplicationController
  def index
    @users = User.where(active: true).order(:last_login_at)
  end

end

# app/models/user.rb
class User < ActiveRecord::Base

  scope :active, -> { where(active: true) }
  scope :by_last_login_at, -> { order(:lasst_login_at) }

end

# app/controllers/users_controller.rb
class UsersController < ApplicationController

  def index
    @users = User.active.by_last_login_at
  end

end

<!-- app/views/posts/show.html.erb -->
...

<h2>
  <%= "#{@comments.count} Comment#{@comments.count == 1 ? '' : 's'}" %>
</h2>

...

# app/helpers/comments_helper.rb
module CommentsHelper
  def comments_count(comments)
    "#{comments.count} Comment#{comments.count == 1 ? '' : 's'}"
  end
end

<!-- app/views/posts/show.html.erb -->
<h2>
  <%= comments_count(@comments) %>
</h2>

# app/models/topic.rb
class Topic < ActiveRecord::Base

  def self.r_topics(questions)
    rt = []

    questions.each do |q|
      topics = q.topics

      topics.each do |t|
        if t.enabled?
          rt << t
        end
      end
    end

    Topic.where(id: rt)
  end

end

# app/models/topic.rb
class Topic < ActiveRecord::Base

  def self.related(questions)
    related_topics = []

    questions.each do |question|
      topics = question.topics

      topics.each do |topic|
        if topic.enabled?
          related_topics << topic
        end
      end
    end

    Topic.where(id: related_topics)
  end

end

# app/services/charge_user.rb
class ChargeUser

  def self.perform(user, amount)
    return false unless user.enabled?

    PaymentGateway.charge(user.account_id, amount)
  end

end

# app/models/user.rb
class User < ActiveRecord::Base

  def disabled?
    !enabled?
  end

end

# app/services/charge_user.rb
class ChargeUser

  def self.perform(user, amount)
    return false if user.disabled?

    PaymentGateway.charge(user.account_id, amount)
  end

end

# app/models/user.rb
class User < ActiveRecord::Base

  def enable!
    update(enabled: true)
  end

end

# app/controllers/users_controller.rb
class UsersController < ApplicationController

  def enable
    user = User.find(params[:id])

    if user.disabled?
      user.enable!
      message = "User enabled"
    else
      message = "User already disabled"
    end

    redirect_to user_path(user), notice: message
  end

end

# app/models/user.rb
class User < ActiveRecord::Base

  def enable!
    if disabled?
      update(enabled: true)
    end
  end

end

# app/controllers/users_controller.rb
class UsersController < ApplicationController

  def enable
    user = User.find(params[:id])

    if user.enable!
      message = "User enabled"
    else
      message = "User already disabled"
    end

    redirect_to user_path(user), notice: message
  end

end

# app/controllers/posts_controller.rb
class PostsController < ApplicationController

  def destroy
    post = Post.find(params[:id])

    if post.enabled? && (user.own_post?(post) || user.admin?)
      post.destroy
      message = "Post destroyed."
    else
      message = "You're not allow to destroy this post."
    end

    redirect_to posts_path, notice: message
  end

end

# app/models/user.rb
class User < ActiveRecord::Base

  def can_destroy_post?(post)
    post.enabled? && (own_post?(post) || admin?)
  end

end

# app/controllers/posts_controller.rb
class PostsController < ApplicationController

  def destroy
    post = Post.find(params[:id])

    if user.can_destroy_post?(post)
      post.destroy
      message = "Post destroyed."
    else
      message = "You're not allow to destroy this post."
    end

    redirect_to posts_path, notice: message
  end

end

# app/models/user.rb
class User < ActiveRecord::Base

  def full_name
    "#{self.first_name} #{self.last_name}"
  end

end

# app/models/user.rb
class User < ActiveRecord::Base

  def full_name
    "#{first_name} #{last_name}"
  end

end

# app/models/user.rb
class User < ActiveRecord::Base

  def full_name
    if name
      name
    else
      "No name"
    end
  end

end

# app/models/user.rb
class User < ActiveRecord::Base

  def full_name
    name ? name : "No name"
  end

end

# app/models/user.rb
class User < ActiveRecord::Base

  def full_name
    name || "No name"
  end

end

def addition(x, y)
  puts binding.local_variables.inspect
  z = x + y
  puts binding.local_variables.inspect
  z
end

> addition(2, 3)
[:x, :y, :z]
[:x, :y, :z]
=> 5

class Cat
  def self.type
    binding.receiver
  end
end

> Cat.type
Cat

class Tiger < Cat
end

> Tiger.type
Tiger

> $stdout.fileno
1
> Dir.new('.').fileno
8

> [1, 'a', 2, 'b', 'c', 3, 'd', 'e', 'f'].slice_before { |e| e.is_a?(Integer) }.to_a
[[1, "a"], [2, "b", "c"], [3, "d", "e", "f"]]

> [1, 'a', 2, 'b', 'c', 3, 'd', 'e', 'f'].slice_before(Integer).to_a
[[1, "a"], [2, "b", "c"], [3, "d", "e", "f"]]

> [1, 'a', 2, 'b', 'c', 3, 'd', 'e', 'f'].slice_after(Integer).to_a
[[1], ["a", 2], ["b", "c", 3], ["d", "e", "f"]]

> [1, 3, 4, 5, 7, 8, 9, 10, 12].slice_when { |a, b| a + 1 != b }.to_a
[[1], [3, 4, 5], [7, 8, 9, 10], [12]]

> Array.new(10) { rand(3) + 1 }.sort.slice_when(&:!=).map { |x| [x.first, x.size] }
[[1, 4], [2, 4], [3, 2]]

> 1.0.next_float
1.0000000000000002

> 1.0000000000000001
1.0

> 2.0.prev_float
1.9999999999999998

> 2.0.next_float
2.0000000000000004

> File.new('test', 'w').birthtime
2015-01-06 19:24:44 -0600

> File.birthtime('test')
2015-01-06 19:24:44 -0600

> File::Stat.new('test').birthtime
2015-01-06 19:24:44 -0600

> 1.itself
1

> [2, 3, 3, 1, 2, 3, 3, 1, 1, 2].group_by(&:itself)
{2=>[2, 2, 2], 3=>[3, 3, 3, 3], 1=>[1, 1, 1]}

def foo(a,b,c)
  [a, b, c]
end

proc  = self.method(:foo).curry
proc2 = proc.call(1, 2)          #=> #<Proc>
proc2.call(3)                    #=> [1,2,3]

def vararg(*args)
  args
end

proc = self.method(:vararg).curry(4)
proc2 = proc.call(:x)      #=> #<Proc>
proc3 = proc2.call(:y, :z) #=> #<Proc>
proc3.call(:a)             #=> [:x, :y, :z, :a]

class Cat
  def speak
    'meow'
  end
end

class Tiger < Cat
  def speak
    'roar'
  end
end

> Tiger.new.method('speak')
#<Method: Tiger#speak>
> Tiger.new.method('speak').super_method
#<Method: Cat#speak>
> Cat.new.method('speak').super_method
nil

{"key": "value"}