在Heroku上使用ENV文件进行制作 [英] Using ENV files in production on Heroku

问题描述

我的 production.rb 环境文件中包含以下配置行，如本文：

  config.cache_store =：mem_cache_store， ENV [MEMCACHEDCLOUD_SERVERS]。split（'，'），{：username => ENV [MEMCACHEDCLOUD_USERNAME]，：password => ENV [MEMCACHEDCLOUD_PASSWORD]} 
  

但是当我尝试部署时，出现错误：
$ b

运行：rake资产：预编译rake中止！

未定义方法 split'for nil ：NilClass

/tmp/build_abdc.../config/environments/production.rb:107:inblock in'

这是因为配置变量在编译期间不可用。有一个Heroku实验室插件，你可以用它来弥补这一点，但Heroku发出警告：使用此实验室功能与Heroku最佳实践相反。

那么在生产配置中使用ENV变量时，最佳做法是什么？他们是否应该全部被包装在救援处理程序中，以便Heroku在编译过程中忽略它们？ 我们最终只是检查ENV分配之前的var。看起来这就是你在Heroku的config / initializers中使用ENV变量时需要的模式：

 ＃注意：ENV变量不是'因此必须检查它们是否存在：
如果ENV [MEMCACHEDCLOUD_SERVERS] 
 config.cache_store =：mem_cache_store，ENV [MEMCACHEDCLOUD_SERVERS]。split（'，'），{ ：username => ENV [MEMCACHEDCLOUD_USERNAME]，：password => ENV [MEMCACHEDCLOUD_PASSWORD]} 
结束
  

另请参阅：
https://devcenter.heroku.com/articles / rails-asset-pipeline＃failure-in-the-assets-precompile-task

I've got the following configuration line in my production.rb environment file, as instructed in this article:

  config.cache_store = :mem_cache_store, ENV["MEMCACHEDCLOUD_SERVERS"].split(','), { :username => ENV["MEMCACHEDCLOUD_USERNAME"], :password => ENV["MEMCACHEDCLOUD_PASSWORD"] }

But when I try to deploy, I'll get an error:

Running: rake assets:precompile rake aborted!
undefined method split' for nil:NilClass
/tmp/build_abdc.../config/environments/production.rb:107:inblock in '

This is because config vars are not available during compilation. There's a Heroku labs add-on that you can supposedly use to remedy this, but it comes with a warning from Heroku that "Using this labs feature is considered counter to Heroku best practices."

So then what is the best practice when it comes to using ENV vars in production config? Should they just all be wrapped in rescue handlers so that Heroku ignores them during compilation?

解决方案

We ended up just checking for the ENV var before assigment. Looks like that's the pattern you need whenever you use ENV vars in config/initializers on Heroku:

  # NOTE: ENV vars aren't available during slug comiplation, so must check if they exist:
  if ENV["MEMCACHEDCLOUD_SERVERS"]
    config.cache_store = :mem_cache_store, ENV["MEMCACHEDCLOUD_SERVERS"].split(','), { :username => ENV["MEMCACHEDCLOUD_USERNAME"], :password => ENV["MEMCACHEDCLOUD_PASSWORD"] }
  end

See also: https://devcenter.heroku.com/articles/rails-asset-pipeline#failures-in-the-assets-precompile-task

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