即使资产没有变化，也会发生 Rails 资产预编译

Question

我正在 AWS Opsworks 上运行 rails 堆栈。在 before_symlink.rb 部署钩子中，我有以下代码。

rails_env = new_resource.environment["RAILS_ENV"]
shared_path = "#{new_resource.deploy_to}/shared"

# create shared directory for assets, if it doesn't exist
directory "#{shared_path}/assets" do
  mode 0770
  action :create
  recursive true
  not_if do
    Dir.exists?("#{shared_path}/assets")
  end
end

# symlink current deploy's asset folder to shared assets each deploy
link "#{release_path}/public/assets" do
  to "#{shared_path}/assets"
end

# precompile assets into public/assets (which is symlinked to shared assets folder)
execute "rake assets:precompile" do
  cwd release_path
  command "bundle exec rake assets:precompile --trace"
  environment 'RAILS_ENV' => rails_env
end

问题是即使没有更改，资产也会一直预编译，尽管它们位于符号链接的共享文件夹中。我在 Rails 4.1.2 上运行，我猜 Rails 足够智能，可以在 Rails 4 之后只编译更改的资产？为什么会这样？

更新

现在已经解决了。

我错过了将 /tmp/cache 符号链接到 /shared/tmp/cache。这是 sprockets 存储缓存文件的地方。

更新代码。

# Precompile assets. Assets are compiled into shared/assets and shared between deploys.
rails_env = new_resource.environment["RAILS_ENV"]
shared_path = "#{new_resource.deploy_to}/shared"

# create shared directory for assets, if it doesn't exist
directory "#{shared_path}/assets" do
  mode 0770
  action :create
  recursive true
  not_if do
    Dir.exists?("#{shared_path}/assets")
  end
end

#create shared directory to store sprockets cache
directory "#{shared_path}/tmp/cache" do
  mode 0770
  action :create
  recursive true
  not_if do
    Dir.exists?("#{shared_path}/tmp/cache")
  end
end

# symlink current deploy's asset folder to shared assets each deploy
link "#{release_path}/public/assets" do
  to "#{shared_path}/assets"
end

# symlink current deploy's sprockets cache  folder to shared cache folder on each deploy
link "#{release_path}/tmp/cache" do
  to "#{shared_path}/tmp/cache"
end

# precompile assets into public/assets (which is symlinked to shared assets folder)
execute "rake assets:precompile" do
  cwd release_path
  command "bundle exec rake assets:precompile --trace"
  environment 'RAILS_ENV' => rails_env
end

Answer 1

OpsWorks 会在每次部署时重建您的整个 Rails 应用程序，并保留大量备份副本。它应该在如下路径中创建它：

/srv/www/yourappname/current

您可以通过 ssh 进入您的服务器来确认这一点。如果你去路径

ls -la /srv/www/yourappname/releases

您应该会看到一些带有日期时间戳名称的文件夹。 如果您查看内容，它们将包含您的整个 Rails 应用程序。 如果在部署过程中出现问题，这可以很容易地回滚。

由于每个文件夹基本上都是您的应用程序的新安装，因此需要进行资产预编译，否则当前版本将没有任何资产。这种类型的部署不只是让同一个目录做一个 git pull origin master

更新：看起来这是带有 Sprockets 的 issue，已在此 pull request 中解决，因此请确保您的 gem sprockets 版本包含此 commit。看起来它已包含在 v4.0.0beta1 和 v4.0.0beta2 中，所以尝试一下，如果没有，请尝试降级到 >=2.12.4 as per this comment