Rails 3.1.3 on Heroku: (No route matches [GET] "/assets/rails.png")

Question

I've installed a few basic apps on Heroku without problem, and this one (Rails 3.1.3) seemed fine in that it showed Rails welcome page

public/index.html.erb

but when I removed that page and then set

root :to => 'users#index'

I got a problem. In the heroku logs it said there's a routing error

ActionController::RoutingError (No route matches [GET] "/assets/rails.png"):

Does anyone know what this is about?

2012-01-14T21:48:29+00:00 heroku[web.1]: Process exited
2012-01-14T21:48:33+00:00 app[web.1]: >> Thin web server (v1.2.6 codename Crazy Delicious)
2012-01-14T21:48:33+00:00 app[web.1]: >> Maximum connections set to 1024
2012-01-14T21:48:33+00:00 app[web.1]: >> Listening on 0.0.0.0:32570, CTRL+C to stop
2012-01-14T21:48:34+00:00 heroku[web.1]: State changed from starting to up
2012-01-14T21:48:35+00:00 app[web.1]: cache: [GET /] miss
2012-01-14T21:48:36+00:00 app[web.1]: 
2012-01-14T21:48:36+00:00 app[web.1]: 
2012-01-14T21:48:36+00:00 app[web.1]: Started GET "/assets/rails.png" for 216.251.147.10 at 2012-01-14 13:48:36 -0800
2012-01-14T21:48:36+00:00 app[web.1]: 
2012-01-14T21:48:36+00:00 app[web.1]: ActionController::RoutingError (No route matches [GET] "/assets/rails.png"):
2012-01-14T21:48:36+00:00 app[web.1]:   
2012-01-14T21:48:36+00:00 app[web.1]: 
2012-01-14T21:48:36+00:00 app[web.1]: 
2012-01-14T21:48:36+00:00 app[web.1]: cache: [GET /assets/rails.png] miss
2012-01-14T21:48:35+00:00 heroku[router]: GET mmcarrier.heroku.com/ dyno=web.1 queue=0 wait=0ms service=19ms status=200 bytes=5907
2012-01-14T21:48:36+00:00 heroku[router]: GET mmcarrier.heroku.com/assets/rails.png dyno=web.1 queue=0 wait=0ms service=30ms status=404 bytes=728
2012-01-14T21:48:46+00:00 app[web.1]: cache: [GET /] miss
2012-01-14T21:48:46+00:00 app[web.1]: 
2012-01-14T21:48:46+00:00 app[web.1]: 
2012-01-14T21:48:46+00:00 app[web.1]: Started GET "/assets/rails.png" for 216.251.147.10 at 2012-01-14 13:48:46 -0800
2012-01-14T21:48:46+00:00 app[web.1]: 
2012-01-14T21:48:46+00:00 app[web.1]: ActionC

2012-01-14T21:48:46+00:00 app[web.1]:   
2012-01-14T21:48:46+00:00 app[web.1]: 
2012-01-14T21:48:46+00:00 app[web.1]: 
2012-01-14T21:48:46+00:00 app[web.1]: cache: [GET /assets/rails.png] miss
2012-01-14T21:48:46+00:00 app[web.1]: cache: [GET /favicon.ico] miss
2012-01-14T21:48:46+00:00 heroku[router]: GET mmcarrier.heroku.com/favicon.ico dyno=web.1 queue=0 wait=0ms service=3ms status=200 bytes=0
2012-01-14T21:48:46+00:00 heroku[router]: GET mmcarrier.heroku.com/ dyno=web.1 queue=0 wait=0ms service=6ms status=200 bytes=5907
2012-01-14T21:48:46+00:00 heroku[router]: GET mmcarrier.heroku.com/assets/rails.png dyno=web.1 queue=0 wait=0ms service=4ms status=404 bytes=728
2012-01-14T21:48:59+00:00 app[web.1]: cache: [GET /] miss
2012-01-14T21:48:59+00:00 heroku[router]: GET mmcarrier.heroku.com/ dyno=web.1 queue=0 wait=0ms service=5ms status=200 bytes=5907
2012-01-14T21:48:59+00:00 app[web.1]: 
2012-01-14T21:48:59+00:00 app[web.1]: 
2012-01-14T21:48:59+00:00 app[web.1]: Started GET "/assets/rails.png" for 216.251.147.10 at 2012-01-14 13:48:59 -0800
2012-01-14T21:48:59+00:00 app[web.1]: 
2012-01-14T21:48:59+00:00 app[web.1]: ActionController::RoutingError (No route matches [GET] "/assets/rails.png"):
2012-01-14T21:48:59+00:00 app[web.1]:   
2012-01-14T21:48:59+00:00 app[web.1]: 
2012-01-14T21:48:59+00:00 app[web.1]: 
2012-01-14T21:48:59+00:00 app[web.1]: cache: [GET /assets/rails.png] miss
2012-01-14T21:48:59+00:00 heroku[router]: GET mmcarrier.heroku.com/assets/rails.png dyno=web.1 queue=0 wait=0ms service=3ms status=404 bytes=728
2012-01-14T21:49:18+00:00 app[web.1]: 
2012-01-14T21:49:18+00:00 app[web.1]: 
2012-01-14T21:49:18+00:00 app[web.1]: Started GET "/assets/rails.png" for 216.251.147.10 at 2012-01-14 13:49:18 -0800
2012-01-14T21:49:18+00:00 app[web.1]: 
2012-01-14T21:49:18+00:00 app[web.1]: ActionController::RoutingError (No route matches [GET] "/assets/rails.png"):
2012-01-14T21:49:18+00:00 app[web.1]: 
2012-01-14T21:49:18+00:00 app[web.1]:   
2012-01-14T21:49:18+00:00 app[web.1]: 
2012-01-14T21:49:18+00:00 app[web.1]: cache: [GET /assets/rails.png] miss
2012-01-14T21:49:18+00:00 heroku[router]: GET mmcarrier.heroku.com/assets/rails.png dyno=web.1 queue=0 wait=0ms service=4ms status=404 bytes=728
2012-01-14T21:49:33+00:00 app[web.1]: cache: [GET /] miss
2012-01-14T21:49:33+00:00 app[web.1]: 
2012-01-14T21:49:33+00:00 app[web.1]: 
2012-01-14T21:49:33+00:00 app[web.1]: Started GET "/assets/rails.png" for 216.251.147.10 at 2012-01-14 13:49:33 -0800
2012-01-14T21:49:33+00:00 app[web.1]: 
2012-01-14T21:49:33+00:00 app[web.1]: ActionController::RoutingError (No route matches [GET] "/assets/rails.png"):
2012-01-14T21:49:33+00:00 app[web.1]:   
2012-01-14T21:49:33+00:00 app[web.1]: 
2012-01-14T21:49:33+00:00 app[web.1]: cache: [GET /assets/rails.png] miss
2012-01-14T21:49:33+00:00 app[web.1]: 
2012-01-14T21:49:34+00:00 app[web.1]: cache: [GET /favicon.ico] miss
2012-01-14T21:49:33+00:00 heroku[router]: GET mmcarrier.heroku.com/ dyno=web.1 queue=0 wait=0ms service=6ms status=200 bytes=5907
2012-01-14T21:49:33+00:00 heroku[router]: GET mmcarrier.heroku.com/assets/rails.png dyno=web.1 queue=0 wait=0ms service=4ms status=404 bytes=728
2012-01-14T21:49:34+00:00 heroku[router]: GET mmcarrier.heroku.com/favicon.ico dyno=web.1 queue=0 wait=0ms service=3ms status=200 bytes=0
2012-01-14T21:50:21+00:00 app[web.1]: cache: [GET /] miss
2012-01-14T21:50:21+00:00 heroku[router]: GET mmcarrier.heroku.com/ dyno=web.1 queue=0 wait=0ms service=4ms status=200 bytes=5907
2012-01-14T21:50:21+00:00 app[web.1]: 
2012-01-14T21:50:21+00:00 heroku[router]: GET mmcarrier.heroku.com/assets/rails.png dyno=web.1 queue=0 wait=0ms service=4ms status=404 bytes=728
2012-01-14T21:50:21+00:00 app[web.1]: Started GET "/assets/rails.png" for 216.251.147.10 at 2012-01-14 13:50:21 -0800
2012-01-14T21:50:21+00:00 app[web.1]: 
2012-01-14T21:50:21+00:00 app[web.1]: 
2012-01-14T21:50:21+00:00 app[web.1]: cache: [GET /assets/rails.png] miss
2012-01-14T21:50:21+00:00 app[web.1]: ActionController::RoutingError (No route matches [GET] "/assets/rails.png"):
2012-01-14T21:50:21+00:00 app[web.1]:   
2012-01-14T21:50:21+00:00 app[web.1]: 
2012-01-14T21:50:21+00:00 app[web.1]: 
2012-01-14T21:52:42+00:00 heroku[slugc]: Slug compilation started
2012-01-14T21:52:54+00:00 heroku[api]: Deploy 983a24d by [email protected]
2012-01-14T21:52:54+00:00 heroku[api]: Release v8 created by [email protected]
2012-01-14T21:52:54+00:00 heroku[web.1]: State changed from up to bouncing
2012-01-14T21:52:54+00:00 heroku[web.1]: State changed from bouncing to created
2012-01-14T21:52:54+00:00 heroku[web.1]: State changed from created to starting
2012-01-14T21:52:55+00:00 heroku[slugc]: Slug compilation finished
2012-01-14T21:53:01+00:00 heroku[web.1]: State changed from starting to up
2012-01-14T21:53:05+00:00 heroku[router]: GET mmcarrier.heroku.com/assets/rails.png dyno=web.1 queue=0 wait=0ms service=37ms status=404 bytes=728
2012-01-14T21:53:17+00:00 heroku[router]: GET mmcarrier.heroku.com/assets/rails.png dyno=web.1 queue=0 wait=0ms service=5ms status=404 bytes=728
2012-01-14T21:53:36+00:00 heroku[router]: GET mmcarrier.heroku.com/assets/rails.png dyno=web.1 queue=0 wait=0ms service=2ms status=404 bytes=728
2012-01-14T21:53:38+00:00 heroku[router]: GET mmcarrier.heroku.com/ dyno=web.1 queue=0 wait=0ms service=107ms status=500 bytes=728
2012-01-14T21:53:40+00:00 heroku[router]: GET mmcarrier.heroku.com/ dyno=web.1 queue=0 wait=0ms service=20ms status=500 bytes=728
2012-01-14T21:53:49+00:00 heroku[run.1]: State changed from created to starting
2012-01-14T21:53:52+00:00 heroku[run.1]: State changed from starting to up
2012-01-14T21:53:57+00:00 heroku[run.1]: State changed from up to complete
2012-01-14T21:53:57+00:00 heroku[run.1]: Process exited
2012-01-14T21:55:15+00:00 heroku[router]: GET mmcarrier.heroku.com/assets/rails.png dyno=web.1 queue=0 wait=0ms service=35ms status=404 bytes=728
2012-01-14T21:55:17+00:00 heroku[router]: GET mmcarrier.heroku.com/assets/rails.png dyno=web.1 queue=0 wait=0ms service=3ms status=404 bytes=728
2012-01-14T21:55:22+00:00 heroku[router]: GET mmcarrier.heroku.com/ dyno=web.1 queue=0 wait=0ms service=12ms status=500 bytes=728
2012-01-14T21:56:18+00:00 heroku[router]: GET mmcarrier.heroku.com/ dyno=web.1 queue=0 wait=0ms service=12ms status=500 bytes=728

Answer 1

No need to precompile and clutter your git!

heroku will precompile your assets

with rails 3.1.x you added this to application.rb

config.assets.initialize_on_precompile = false

UPDATE 16th july2012

also rails 3.2.x

it seems to be problem with ActiveRecord and database.yml ! If you don't use regular database, but use MongoDB, you will not need the above. However, if you do, you'll need to disable the initilize, as activerecord reads database tables when initializing, but database is not available at precompile phase at heroku.

with MongoDB it is not necessary.

/UPDATE

rails 3.2.x : Have a look at the top of application.rb. The OMA comments are mine, added for clarity

if defined?(Bundler)
  # If you precompile assets before deploying to production, use this line
  "OMA - comment this line"
  #Bundler.require(*Rails.groups(:assets => %w(development test)))
  # If you want your assets lazily compiled in production, use this line
  "OMA - uncomment this line"
  Bundler.require(:default, :assets, Rails.env)
end

Answer 2

It looks like you may not have precompiled your assets before you pushed to Heroku, try:

rake assets:precompile
git add .
etc etc

I think that should help. For more information, see here: http://devcenter.heroku.com/articles/rails31_heroku_cedar