Capistrano with rails - basic notes

詳細的東西還是看 project’s github page 比較快 - Capistrano@github

Capistrano 剛開始寫 deploy script 時真的會有點搞不太懂 XD
記錄一下使用 ‘capistrano’ 把特定的 github repo 抓到 remote server

安裝

先在 Gemfile 加入:

gem 'capistrano', '~> 3.2.0'   

然後安裝~

bundle install

步驟大概會是：

假設已經寫完 capistrano 了，執行 script 時，
capistrano 會先利用 script 裡提供的 server ip 以及 public key，
先連線到 remote server，接著再到 github 上拉 code 到指定的目錄裡，
再重開 server。

產生相關檔案

bundle exec cap install 

會產生以下檔案: (copy from Capistrano@github)

├── Capfile
├── config
│   ├── deploy
│   │   ├── production.rb
│   │   └── staging.rb
│   └── deploy.rb
└── lib
    └── capistrano
            └── tasks

deploy.rb 通常是設定 source control 的類型 (可以設定 git, hg, svn)，
project repo 的路徑，要 deploy 到 server 的哪個目錄等等，
config/deploy/* 底下的檔案則是根據不同的 stage 分別設定，
以下是 deploy.rb, production.rb 的一些簡單設定

# config valid only for Capistrano 3.1
lock '3.2.1'

set :application, 'application_name'
set :repo_url, 'github_repo_url'

set :deploy_via, :copy

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

# Default deploy_to directory is /var/www/my_app
set :deploy_to, '/server/www/path/'

# Default value for :scm is :git
set :scm, :git

# Default value for :format is :pretty
set :format, :pretty

# Default value for :log_level is :debug
set :log_level, :debug

# Default value for :pty is false
# set :pty, true

# Default value for :linked_files is []
# set :linked_files, %w{config/database.yml}

# Default value for linked_dirs is []
# set :linked_dirs, %w{bin log tmp/pids tmp/cache tmp/sockets vendor/bundle public/system}

# Default value for default_env is {}
# set :default_env, { path: "/opt/ruby/bin:$PATH" }

# Default value for keep_releases is 5
# set :keep_releases, 5

namespace :deploy do

  desc 'Restart application'
  task :restart do
    on roles(:app), in: :sequence, wait: 5 do
      # Your restart mechanism here, for example:
      execute :mkdir, '-p', "#{ release_path }/tmp"
      execute :touch, release_path.join('tmp/restart.txt')
    end
  end

  after :publishing, :restart

  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
      #  execute :rake, 'cache:clear'
      # end
    end
  end

end

production.rb:

# Simple Role Syntax
# ==================
# Supports bulk-adding hosts to roles, the primary server in each group
# is considered to be the first unless any hosts have the primary
# property set.  Don't declare `role :all`, it's a meta role.

role :app, %w{app@server}
role :web, %w{web@server}
role :db,  %w{db@server}


# Extended Server Syntax
# ======================
# This can be used to drop a more detailed server definition into the
# server list. The second argument is a, or duck-types, Hash and is
# used to set extended properties on the server.

server 'server_ip', user: 'server_user', roles: %w{app}, my_property: :my_value


# Custom SSH Options
# ==================
# You may pass any option but keep in mind that net/ssh understands a
# limited set of options, consult[net/ssh documentation](http://net-ssh.github.io/net-ssh/classes/Net/SSH.html#method-c-start).
#
# Global options
# --------------
#  set :ssh_options, {
#    keys: %w(/home/rlisowski/.ssh/id_rsa),
#    forward_agent: true
#    auth_methods: %w(password)
#  }
#
# And/or per server (overrides global)
# ------------------------------------
 server 'server_ip',
   user: 'server_user',
   ssh_options: {
     keys: %w(/user/.ssh/id_rsa),
     forward_agent: false,
     auth_methods: %w(publickey password)
   }

設定完後，因為這邊是設定 production.rb
因此執行以下指令 deploy 到 production server

$ bundle exec cap production deploy

如果 exit status 0 (successful).
那就是成功啦~