ruby-on-rails – 为什么我需要在应用服务器而不是Web服务器上预

发布时间：2020-12-17 03:05:18 所属栏目：百科来源：网络整理

导读：我正在为这个小型的ubuntu precision64服务器设置部署一个简单的Rails应用程序： * 1运行nginx的Web服务器 * 2个运行独角兽的应用服务器 * 1 db服务器运行 postgresql 我的服务器配置了Puppet,我正在用capistrano推送应用程序. 我的Capfile load 'deploy'# U

我正在为这个小型的ubuntu precision64服务器设置部署一个简单的Rails应用程序：
* 1运行nginx的Web服务器
* 2个运行独角兽的应用服务器
* 1 db服务器运行 postgresql

我的服务器配置了Puppet,我正在用capistrano推送应用程序.

我的Capfile

load 'deploy'
# Uncomment if you are using Rails' asset pipeline
load 'deploy/assets'
load 'config/deploy' # remove this line to skip loading any of the default tasks

deploy.rb文件非常简单

# Execute "bundle install" after deploy,but only when really needed
require "bundler/capistrano"

# Name of the application in scm (GIT)
set :application,"devops-test-app"
set :repository,"https://github.com/geoffroymontel/devops-test-app.git"
set :scm,:git

set :deploy_to,"/var/www/#{application}"

# server there the web server is running (nginx)
role :web,"172.16.0.2"

# server there the db is running
# This is where Rails migrations will run
role :db,"172.16.0.3",:primary => true

# servers there the app servers are running (unicorn)
role :app,"172.16.0.4","172.16.0.5"

set :rails_env,:production

# user on the server
set :user,"deployer"
set :use_sudo,false

namespace :deploy do 
  task :start,:roles => :app,:except => { :no_release => true } do
    run "service unicorn_#{application} start"
  end

  task :stop,:except => { :no_release => true } do
    run "service unicorn_#{application} stop"
  end

  task :restart,:except => { :no_release => true } do
    run "service unicorn_#{application} restart"
  end

  task :copy_in_database_yml do
    run "cp #{shared_path}/config/database.yml #{latest_release}/config/"
  end

  # Precompile assets
  # I have to precompile the assets on the app servers too,and I don't really know why...
  # namespace :assets do
  #   task :precompile,:roles => [:web,:app],:except => { :no_release => true } do
  #     run %Q{cd #{latest_release} && #{rake} RAILS_ENV=#{rails_env} #{asset_env} assets:precompile}
  #   end
  # end
end

before "deploy:assets:precompile","deploy:copy_in_database_yml"

如果我不在应用服务器上预编译资产,则应用程序将失败.

$cap ROLES="app" COMMAND="cat /var/www/devops-test-app/current/log/production.log" invoke
  * 2013-05-01 21:43:10 executing `invoke'
  * executing "cat /var/www/devops-test-app/current/log/production.log"
    servers: ["172.16.0.4","172.16.0.5"]
    [172.16.0.5] executing command
 ** [out :: 172.16.0.5] Connecting to database specified by database.yml
 ** [out :: 172.16.0.5] Connecting to database specified by database.yml
 ** [out :: 172.16.0.5] Started GET "/posts" for 172.16.0.2 at 2013-05-01 19:42:10 +0000
 ** [out :: 172.16.0.5] Processing by PostsController#index as HTML
 ** [out :: 172.16.0.5] Rendered posts/index.html.erb within layouts/application (25.7ms)
 ** [out :: 172.16.0.5] Completed 500 Internal Server Error in 122ms
 ** [out :: 172.16.0.5] 
 ** [out :: 172.16.0.5] ActionView::Template::Error (application.css isn't precompiled):
 ** [out :: 172.16.0.5] 2: <html>
 ** [out :: 172.16.0.5] 3: <head>
 ** [out :: 172.16.0.5] 4:   <title>DevopsTestApp</title>
 ** [out :: 172.16.0.5] 5:   <%= stylesheet_link_tag    "application",:media => "all" %>
 ** [out :: 172.16.0.5] 6:   <%= javascript_include_tag "application" %>
 ** [out :: 172.16.0.5] 7:   <%= csrf_meta_tags %>
 ** [out :: 172.16.0.5] 8: </head>
 ** [out :: 172.16.0.5] app/views/layouts/application.html.erb:5:in `_app_views_layouts_application_html_erb__677166568443748084_17536100'
 ** [out :: 172.16.0.5] app/controllers/posts_controller.rb:7:in `index'

如果我取消注释deploy.rb中的注释行,一切都很好.

但为什么？？
我认为您只需要在Web服务器上编译资产,而不是在应用服务器上编译资产.

请帮我理解为什么:)

谢谢,最好的问候

若弗鲁瓦

解决方法

因为,除其他外,Rails会生成预编译资产的清单,包括文件名中文件的哈希值,然后在页面中包含资源时使用这些名称.当你说image_url(‘foo.jpg’)时,Rails最终会在源代码中生成foo-b48cf0140bea12734db05ebcdb012f1d265bed84.jpg.

Rails需要知道要为这些资产使用的编译名称,因此它必须具有清单,因此预编译需要在应用服务器上完成.

看一下public / assets / manifest.yml – 这是Rails需要的文件,以便正确地提供预编译资产.

（编辑：李大同）

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