Heroku does NOT compile files under assets pipelines in Rails 4 - heroku

Question

Everything goes well in local machine with assets pipeline in Rails 4 and Ruby 2.0. But when deploying to heroku, it is shown that:
-----> Preparing app for Rails asset pipeline
Running: rake assets:precompile
I, [2013-03-12T03:28:29.908234 #912] INFO -- : Writing /tmp/build_1n6yi8lwna3sj/public/assets/rails-2ee5a98f26fbf8c6c461127da73c47eb.png
I, [2013-03-12T03:28:29.914096 #912] INFO -- : Writing /tmp/build_1n6yi8lwna3sj/public/assets/trash-3c3c2861eca3747315d712bcfc182902.png
I, [2013-03-12T03:28:33.963234 #912] INFO -- : Writing /tmp/build_1n6yi8lwna3sj/public/assets/application-bf2525bd32aa2a7068dbcfaa591b3874.js
I, [2013-03-12T03:28:40.362850 #912] INFO -- : Writing /tmp/build_1n6yi8lwna3sj/public/assets/application-13374a65f29a3b4cea6f8da2816ce7ff.css
Asset precompilation completed (14.36s)
Heroku seems to compile files but put it in /tmp without any errors. My questions are:
How come Heroku compile assets files to /tmp?
My last solution was to run RAILS_ENV=production bundle exec rake assets:precompile locally, but this generated a manifest-xxxxxx.json in public/assets, rather than manifest.yml, so that heroku doesn't detect the JSON manifest file. I sorted it out by manually created a yml from the json file and heroku became happy. Has heroku's approach been outdated?

Answer 1

Heroku's asset plugins no longer work since Rails 4 does not support plugins. You need to use Heroku's asset gems instead. Place this in your Gemfile:
group :production do
gem 'rails_log_stdout', github: 'heroku/rails_log_stdout'
gem 'rails3_serve_static_assets', github: 'heroku/rails3_serve_static_assets'
end
Follow Heroku's guide on getting started with Rails 4.
Update (07/22/2013): Heroku now supplies a different gem to precompile assets.
group :production do
gem 'rails_12factor'
end

Answer 2

You need to config Rails to serve static assets in production: config/environments/production.rb
SampleApp::Application.configure do
.
.
.
config.serve_static_assets = true
.
.
.
end
UPDATE:
In Rails 4 is deprecated, and has been changed by:
config.serve_static_files = true

Answer 3

Since rails 4 replaced manifest.yml with manifest-(fingerprint).json, you'll want to enable static asset serving.
From Getting Started with Rails 4.x on Heroku:
gem 'rails_12factor', group: :production
then
bundle install
and, finally,
git push heroku
Fixed the issue for me. Hope this helps!

Answer 4

I run exactly into the same problem.
I set config.serve_static_assets = true in my environments/production.rb file until heroku wont't support the new manifest format.
So it is a temporal solution until heroku support will be added.

Answer 5

After hours of googling in which none of the guides on Heroku or the suggestions on StackOverFlow helped me, I finally ran into this blog post which offered this clue:
heroku labs:enable user-env-compile --app=YOUR_APP
Without this, the asset pipeline will always try to init the whole app and connect to the database (despite all the things you may have read that rails 4 now longer does this). This exposes your Heroku configuration to Rails so it can boot up successfully and run rake tasks like assets:precompile.

Answer 6

I needed to use this gem:
gem 'rails_12factor', group: :production #need this for rails 4 assets on heroku
And in /config/environments/production.rb I needed to set:
config.assets.compile = true
My understanding is that the rails_12_factor gem sets config.serve_static_assets = true, amongst other things.

Answer 7

In my case, assets compiled following the instructions above but it wasn't picking the bootstrap glyphicons 'fontawesome-webfont' so this worked for me finally after wasting so many hours researching.
Gem file
gem 'rails_12factor', group: :production
bundle install
config/application.rb
config.assets.precompile += %w(*.png *.jpg *.jpeg *.gif,
"fontawesome-webfont.ttf",
"fontawesome-webfont.eot",
"fontawesome-webfont.svg",
"fontawesome-webfont.woff")
config.assets.precompile << Proc.new do |path|
if path =~ /\.(css|js)\z/
full_path = Rails.application.assets.resolve(path).to_path
app_assets_path = Rails.root.join('app', 'assets').to_path
if full_path.starts_with? app_assets_path
puts "including asset: " + full_path
true
else
puts "excluding asset: " + full_path
false
end
else
false
end
end
environment/production.rb
config.serve_static_assets = true
Then finally, I ran
rake assets:precompile RAILS_ENV=production and pushed it to heroku and that worked.

Answer 8

This was an issue with the Heroku Ruby Buildpack, but an update was deployed today (2013-05-21). Please try it out and let us know.
To answer your questions:
#1) This is sprockets output; things are compiled to /tmp and then moved (See here in Sprockets). To my knowledge this has always been done this way, but it wasn't until Sprockets version was updated in Rails that we got this new debug-type output.
#2) Previously assets:precompile genereated a manifest.json file, but now in Rails 4 the manifest file has a fingerprint in it, which wasn't detected previously. This was fixed with #74.

Answer 9

I added this to the top of one of my css.scss files in the assets/stylesheets/ folder.
#import "font-awesome";
then ran..
rake assets:clean
and...
rake assets:precompile RAILS_ENV=production

Answer 10

In Rails 4.2.4 your production.rb has the line:
config.serve_static_files = ENV['RAILS_SERVE_STATIC_FILES'].present?
That means, gem 'rails_12factor', group: :production doesn`t need to change it to true, as it can be set through the heroku environment variables. You also will get a warning if you remove the rails_12factor gem.
If you have problems with assets, login to the heroku console heroku run rails console and find out the asset path for a file puts helper.asset_path("application.js") .
One strange behaviour I noticed between development and production, when the file ending is not provided:
With a image /assets/images/image_01.jpg the following output from asset_pathsdiffers:
Development:
development > puts helper.asset_path('profile_01')
=> /assets/profile_01-bbd16aac5ef1d295411af44c103fcc631ab90ee94957414d4c01c3aed1055714.jpg
development > puts helper.asset_path('profile_01.jpg')
=> /assets/profile_01-bbd16aac5ef1d295411af44c103fcc631ab90ee94957414d4c01c3aed1055714.jpg
Production:
development > puts helper.asset_path('profile_01')
=> /profile_01
development > puts helper.asset_path('profile_01.jpg')
=> /assets/profile_01-bbd16aac5ef1d295411af44c103fcc631ab90ee94957414d4c01c3aed1055714.jpg
You do not have to run RAILS_ENV=production rake assets:precompile, heroku does this for you during deploy. Also you do not have to precompile the assets in development and push them to heroku.

Answer 11

Apart from ensuring you have the 'rails_12factor' gem installed the only thing you need to do is this.
# config/application.rb
config.assets.paths << Rails.root.join('vendor', 'assets')
It seems that although Rails knows exactly what it wants, Heroku needs reminding to include the assets folder as part of the assets paths.

Answer 12

Use Image Extensions
I had this same issue, but for a different reason.
Instead of
<%= asset_path 'facebook-link' %>
Use:
<%= asset_path 'facebook-link.png' %>
While the first one worked locally, when I pushed to Heroku my images were breaking and I had no clue why. Using the full file extension fixed the problem :)

Answer 13

Add this gem gem 'rails_serve_static_assets'
https://github.com/heroku/rails_serve_static_assets

Answer 14

If you are using controller specific assets as in:
<%= javascript_include_tag params[:controller] %> or <%= javascript_include_tag params[:controller] %>
Then in production you will need to explicitly precompile those (in development rails compiles files on the fly).
See official Rails guide here: http://guides.rubyonrails.org/asset_pipeline.html#controller-specific-assets
To precompile as explained in the guides (here: http://guides.rubyonrails.org/asset_pipeline.html#precompiling-assets) you will need to add the following to the config/application.rb
# config/application.rb
config.assets.precompile << Proc.new do |path|
if path =~ /\.(css|js)\z/
full_path = Rails.application.assets.resolve(path).to_path
app_assets_path = Rails.root.join('app', 'assets').to_path
if full_path.starts_with? app_assets_path
puts "including asset: " + full_path
true
else
puts "excluding asset: " + full_path
false
end
else
false
end
end

Answer 15

I figure I'll add this as an answer since this question is linked from the Heroku Support page if you search for "assets".
This is mostly for people who are updating their app to Rails 4, but after going through this - and many other SO posts - what finally got me was changing the following in production.rb:
config.action_dispatch.x_sendfile_header = "X-Sendfile"
To:
config.action_dispatch.x_sendfile_header = nil
I hadn't caught this when I upgraded and as usual this took me forever to figure out. Hopefully it helps someone else! Shout out to PatrickEm who asked/answered the same in his question.

Answer 16

This may not answer the original question's root cause, But I was having a similar symptom with a different root cause.
Pre-compilation of a JPEG files changes the file extension to JPG, meaning that asset_path("my_image.jpeg") and asset_path("my_image") didn't work. Remove the "e" from JPEG and voila, it works.
Others have described the same problem here https://blazarblogs.wordpress.com/2016/04/06/rails-force-to-precompile-jpeg-to-jpg/
Is this a bug? Or desired behaviour? And also weird that it only doesn't work in my Heroku-hosted production environment. Maybe they have some sort of configuration.