部署rails应用程序的Capistrano——如何处理长时间的迁移?

So I am using Capistrano to deploy a rails application to my production server (apache+passenger) and at the moment deployment usually goes along the lines:

因此，我正在使用Capistrano将一个rails应用程序部署到我的生产服务器(apache+passenger)上，目前部署通常是这样的:

$cap deploy
$cap deploy:migrations

It got me wondering, let's say my db:migrations took a long time to execute on the production server (a big refactor of the db schema) - in this case what is best practice with Capistrano? What happens if users are connected to my application at the time of deployment? Should I gracefully send users to a static placeholder page while the database is being updated? Does Capistrano handle this automagically? Do I need to code up a recipe to help with this? Or does the internal mechanisms of rails / passenger mean that I don't have to worry at all about this particular case?

让我感到疑惑的是，假设我的db:迁移花了很长时间才在生产服务器上执行(这是db模式的一个大重构)——在这种情况下，Capistrano的最佳实践是什么?如果用户在部署时连接到我的应用程序会发生什么?在更新数据库时，是否应该优雅地将用户发送到静态占位符页面?Capistrano是自动处理这个问题的吗?我需要编个食谱来帮助你吗?或者是轨道/乘客的内部机制意味着我完全不需要担心这个特例?

Thanks.

谢谢。

2 个解决方案

#1

You should put up a maintenance page if the application is not going to be available for a while. I use this Capistrano task:

如果应用程序在一段时间内不可用，您应该建立一个维护页面。我使用这个Capistrano任务:

namespace :deploy do
  namespace :web do
    desc <<-DESC
      Present a maintenance page to visitors. Disables your application's web \
      interface by writing a "maintenance.html" file to each web server. The \
      servers must be configured to detect the presence of this file, and if \
      it is present, always display it instead of performing the request.

      By default, the maintenance page will just say the site is down for \
      "maintenance", and will be back "shortly", but you can customize the \
      page by specifying the REASON and UNTIL environment variables:

        $ cap deploy:web:disable \\
              REASON="a hardware upgrade" \\
              UNTIL="12pm Central Time"

      Further customization will require that you write your own task.
    DESC
    task :disable, :roles => :web do
      require 'erb'
      on_rollback { run "rm #{shared_path}/system/maintenance.html" }

      reason = ENV['REASON']
      deadline = ENV['UNTIL']      
      template = File.read('app/views/admin/maintenance.html.erb')
      page = ERB.new(template).result(binding)

      put page, "#{shared_path}/system/maintenance.html", :mode => 0644
    end
  end
end

The app/views/admin/maintenance.html.erb file should contain:

app /视图/ admin / maintenance.html。erb文件应该包含:

<p>We’re currently offline for <%= reason ? reason : 'maintenance' %> as of <%= Time.now.utc.strftime('%H:%M %Z') %>.</p>
<p>Sorry for the inconvenience. We’ll be back <%= deadline ? "by #{deadline}" : 'shortly' %>.</p>

The final step is to configure the Apache virtual host with some directives to look for the maintenance.html file and redirect all requests to it if it's present:

最后一步是使用一些指令配置Apache虚拟主机来查找维护。html文件，如果有，将所有请求重定向到它:

<IfModule mod_rewrite.c>
  RewriteEngine On

  # Redirect all requests to the maintenance page if present
  RewriteCond %{REQUEST_URI} !\.(css|gif|jpg|png)$
  RewriteCond %{DOCUMENT_ROOT}/system/maintenance.html -f
  RewriteCond %{SCRIPT_FILENAME} !maintenance.html
  RewriteRule ^.*$ /system/maintenance.html [L]
</IfModule>

To put the application into maintenance mode, run cap deploy:web:disable and to make it live again do cap deploy:web:enable.

要使应用程序进入维护模式，运行cap deploy:web:disable并使其重新生效，请执行cap deploy:web:enable。

#2

My production deploys generally follow this process:

我的产品部署一般遵循以下流程:

cap production deploy:web:disable which directs all requests to a static maintenance page
cap产品部署:web:禁用，它将所有请求定向到静态维护页面
cap production deploy
帽生产部署
migrations etc, testing each of the servers individually to make sure things are OK
迁移等等，分别测试每个服务器以确保一切正常。
cap production deploy:web:enable to make the site work as it should
cap产品部署:web:使站点能够正常工作

John Topley's response gives you some good in depth info here.

John Topley的回复给了你一些深入的信息。

#1