Image showing as blank in Rails 3.1 on Production (Heroku)

Question

I recently updated my Rails to 3.1.

Here's a part where I added:

<%= asset_path('logo_symbol.png') %>

This renders /assets/logo_symbol.png which works perfectly fine in development environment. However, when i push the code to production on heroku, it shows a broken image, with the url: assets/logo_symbol-135ddc8db2c9b59f032bed7db520137a.png. I am guessing the new name is for the reason of some optimization.

It is however interesting to note that when I go to the assets/logo_symbol-135ddc8db2c9b59f032bed7db520137a.png url on production, I see a blank page, but when I change that url to anything random, like adding numbers to it, it shows a page not found. So clearly it is finding something on that url. It also shows a blank page when I go to /assets/logo_symbol.png directly on production/heroku.

If this is any help, heroku does not precompile successfully when I push the code and heroku's documentation says that there is currently no work around for that issue.

Any help in this will be greatly appreciated.

My guess is that it has something to do with some configuration related to environments. I am attaching contents of my application.rb, development.rb and production.rb files

here are the contents of my production.rb file

 # Settings specified here will take precedence over those in config/application.rb

  # In the development environment your application's code is reloaded on
  # every request.  This slows down response time but is perfect for development
  # since you don't have to restart the webserver when you make code changes.
  config.cache_classes = false

  # Log error messages when you accidentally call methods on nil.
  config.whiny_nils = true

  # Show full error reports and disable caching
  config.consider_all_requests_local       = true
  config.action_controller.perform_caching = false

  # Don't care if the mailer can't send

  #config.action_mailer.default_url_options = { :host => 'localhost:3000' }
  #config.action_mailer.default_url_options = { :host => 'localhost:3000' }
  config.action_mailer.delivery_method = :smtp

  # Print deprecation notices to the Rails logger
  config.active_support.deprecation = :log

  # Only use best-standards-support built into browsers
  config.action_dispatch.best_standards_support = :builtin

  # Do not compress assets
  config.assets.compress = false

  # Expands the lines which load the assets
  config.assets.debug = true
end

module ActiveAdmin
  class Reloader
    def attach!
    end
  end
end

and here are the contents of my development.rb file

 # Settings specified here will take precedence over those in config/application.rb

  # In the development environment your application's code is reloaded on
  # every request.  This slows down response time but is perfect for development
  # since you don't have to restart the webserver when you make code changes.
  config.cache_classes = false

  # Log error messages when you accidentally call methods on nil.
  config.whiny_nils = true

  # Show full error reports and disable caching
  config.consider_all_requests_local       = true
  config.action_controller.perform_caching = false

  # Don't care if the mailer can't send

  #config.action_mailer.default_url_options = { :host => 'localhost:3000' }
  #config.action_mailer.default_url_options = { :host => 'localhost:3000' }
  config.action_mailer.delivery_method = :smtp

  # Print deprecation notices to the Rails logger
  config.active_support.deprecation = :log

  # Only use best-standards-support built into browsers
  config.action_dispatch.best_standards_support = :builtin

  # Do not compress assets
  config.assets.compress = false

  # Expands the lines which load the assets
  config.assets.debug = true
end

module ActiveAdmin
  class Reloader
    def attach!
    end
  end
end

Here are the contents of my production.rb file

  # Settings specified here will take precedence over those in config/application.rb

  # The production environment is meant for finished, "live" apps.
  # Code is not reloaded between requests
  config.cache_classes = true

  # Full error reports are disabled and caching is turned on
  config.consider_all_requests_local       = false
  config.action_controller.perform_caching = true

  # Specifies the header that your server uses for sending files
  config.action_dispatch.x_sendfile_header = "X-Sendfile"

  # For nginx:
  # config.action_dispatch.x_sendfile_header = 'X-Accel-Redirect'

  # If you have no front-end server that supports something like X-Sendfile,
  # just comment this out and Rails will serve the files

  # See everything in the log (default is :info)
  # config.log_level = :debug

  # Use a different logger for distributed setups
  # config.logger = SyslogLogger.new

  # Use a different cache store in production
  # config.cache_store = :mem_cache_store

  # Disable Rails's static asset server
  # In production, Apache or nginx will already do this
  config.serve_static_assets = false

  # Enable serving of images, stylesheets, and javascripts from an asset server
  # config.action_controller.asset_host = "http://assets.example.com"

  # Disable delivery errors, bad email addresses will be ignored
  # config.action_mailer.raise_delivery_errors = false

  #config.action_mailer.default_url_options = { :host => 'ha1.heroku.com' }
  config.action_mailer.delivery_method = :smtp

  # Enable threaded mode
  # config.threadsafe!

  # Enable locale fallbacks for I18n (makes lookups for any locale fall back to
  # the I18n.default_locale when a translation can not be found)
  config.i18n.fallbacks = true

  # Send deprecation notices to registered listeners
  config.active_support.deprecation = :notify

  # Compress JavaScripts and CSS
  #config.assets.compress = true

  # Don't fallback to assets pipeline if a precompiled asset is missed
  config.assets.compile = false

  # Generate digests for assets URLs
  config.assets.digest = true

  # Defaults to Rails.root.join("public/assets")
  # config.assets.manifest = YOUR_PATH

  config.assets.js_compressor  = :uglifier
  config.assets.css_compressor = :scss

I have compared my config files with the rails documentation for 3.1 and seems like I have all the defaults needed. However I am still seeing no image. Any help will be much appreciated

Answer 1

Remove this line from production.rb:

config.action_dispatch.x_sendfile_header = "X-Sendfile"

You should also align the settings in your config files with those in section 9 of the pipeline guides.

Sendfile headers contain information for the upstream webserver of where to find the file (on the file system) to serve it. This removes the load from the backend (Rails/Sprockets). When sendfile is on the HTTP response contains no body (it is zero length) which is why you see nothing.

On heroku the nginx servers do not have access to the application filesystem, so this won't work.

See this note on the Heroku dev site re sendfile.

If you are using heroku, this document outlines the best options for using the pipeline effectively.