Rails 资产在 Heroku 上没有缓存控制 headers

Question

出于某种原因，当我使用 Puma 服务器从 Heroku 为它们提供服务时，我的 Rails 资产不会发送缓存控制 headers。

我在我的 production.rb 中设置了 config.public_file_server.headers = { 'Cache-Control' => 'public, max-age=172800' }，当我运行在我的本地计算机上运行该应用程序时，它工作正常：

Cache-Control: public, max-age=31536000
Etag: "fdffdae515ab907046e7deed6a567968ab3e689f8505a281988bf6892003ff92"
X-Request-Id: 065e704c-1bea-428c-9c40-3cd6b6e4330a
X-Runtime: 0.002411

但是，当我部署到 Heroku 时，我得到以下 headers：

Server: Cowboy
Date: Sat, 10 Jun 2017 18:56:26 GMT
Content-Length: 0
Connection: keep-alive
strict-transport-security: max-age=15552000; includeSubDomains
Via: 1.1 vegur

这似乎有点奇怪，足够令人惊讶。我真的很不明白为什么会这样。我正在使用 Heroku 自己推荐的 Puma Web 服务器——这是我的 Procfile：

web: bundle exec puma -C config/puma.rb

这是我的 puma.rb 配置：

# Puma can serve each request in a thread from an internal thread pool.
# The `threads` method setting takes two numbers a minimum and maximum.
# Any libraries that use thread pools should be configured to match
# the maximum value specified for Puma. Default is set to 5 threads for minimum
# and maximum, this matches the default thread size of Active Record.
#
threads_count = ENV.fetch("RAILS_MAX_THREADS") { 5 }.to_i
threads threads_count, threads_count

# Specifies the `port` that Puma will listen on to receive requests, default is 3000.
#
port        ENV.fetch("PORT") { 3000 }

# Specifies the `environment` that Puma will run in.
#
environment ENV.fetch("RAILS_ENV") { "development" }

# Specifies the number of `workers` to boot in clustered mode.
# Workers are forked webserver processes. If using threads and workers together
# the concurrency of the application would be max `threads` * `workers`.
# Workers do not work on JRuby or Windows (both of which do not support
# processes).

workers ENV.fetch("WEB_CONCURRENCY") {2}

# Use the `preload_app!` method when specifying a `workers` number.
# This directive tells Puma to first boot the application and load code
# before forking the application. This takes advantage of Copy On Write
# process behavior so workers use less memory. If you use this option
# you need to make sure to reconnect any threads in the `on_worker_boot`
# block.

preload_app!

# The code in the `on_worker_boot` will be called if you are using
# clustered mode by specifying a number of `workers`. After each worker
# process is booted this block will be run, if you are using `preload_app!`
# option you will want to use this block to reconnect to any threads
# or connections that may have been created at application boot, Ruby
# cannot share connections between processes.

on_worker_boot do
  ActiveRecord::Base.establish_connection if defined?(ActiveRecord)
end

# Allow puma to be restarted by `rails restart` command.
plugin :tmp_restart

有人有什么想法吗？顺便说一句，与 this post 相反，服务文件的文件类型没有任何区别 - none 其中设置了 cache-control。

Answer 1

找到问题了！

事实证明，没有 Heroku 明显地告诉你，如果你想在资产管道中使用缓存，你需要将 rails_12factor gem 添加到你的 Gemfile:

group :production do
  gem 'rails_12factor'
end

我一添加 rails_12factor gem，一切就开始正常了:)

Answer 2

使用 Rails 5，您可以简单地利用 ActionDispatch::Static 设置自定义 HTTP headers 来提供资产：

# config/environments/production.rb

config.public_file_server.headers = {
  'Cache-Control' => 'public, s-maxage=31536000, max-age=15552000',
  'Expires' => "#{1.year.from_now.to_formatted_s(:rfc822)}"
}

来源：https://blog.bigbinary.com/2015/10/31/rails-5-allows-setting-custom-http-headers-for-assets.html#rails-5-saves-the-day

Rails 资产在 Heroku 上没有缓存控制 headers

Rails assets don't have Cache Control headers with Puma on Heroku

caching

ruby-on-rails

heroku

cache-control

puma