Question

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

  task :restart, :roles => :app, :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？我以为你只需要在网络服务器上编译资产，而不是在应用服务器上。

请帮助我理解原因：）

谢谢，最好的问候

弗鲁瓦

Answer 1

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。当您说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。

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

Answer 2

这是卡皮斯特拉诺的known bug。

1）评论

load 'deploy/assets'

在Capfile上。

2）在deploy.rb文件的顶部添加以下行：

set :assets_role, [:web, :app] load 'deploy/assets'

那就是它！

Answer 3

确保您配置Nginx以提供静态文件而无需访问应用程序服务器。它可能没有配置，因此资产存在但Nginx没有为它们提供服务并且正在回退到应用程序。

为什么我需要在应用服务器而不是Web服务器上预编译Rails资产？

3 个答案: