How to build task 'assets:precompile'

Question

I'm getting that error on my production server, and can't figure out why. It happens when running this command:

bundle exec rake assets:precompile RAILS_ENV=production

I'm using Rails 3.1.0.rc6

Conation

It means there is no task assets:precompile for your application. May be a missing gem or something. – Unruly

which gem would that be? I had just run "gem install rails --pre" and then "rails new ..." – Conation

I am not sure, haven't used 3.1 yet. – Unruly

Are you actually using bundler in production? Is your production server on Heroku? – Emulsoid

@Jack Chu I'm just trying to compile the assets. No, not heroku. – Conation

Are you sure you have sprockets installed? Also, you dont need RAILS_ENV=production, that specific task is always run as production by default. – Emulsoid

In my case I just had to add the gem 'sass-rails' in the gemfile. Maybe it can help someone. – Culbreth

Answer 1

This is most likely due your config/application.rb not requiring rails/all (the default), but some custom requires.

To resolve this, add the following to config/application.rb:

require 'sprockets/railtie'

Specht

This is common issue for Mongoid users that delete rails/all config – Saintmihiel

thank god, someone spotted this, I confirm the said phenomenon – Stalag

bingo. I am indeed a Mongoid user. – Conation

So .. I have this problem, but this wasn't the problem. requiring sprockets/railtie was not missing from my config. – Aciniform

That problem was solved but I got a new error in terminal as: Sprockets::ArgumentError: manifest requires output filename – Somerset

Note that creating a Rails 5 API-only project with $ rails new my_api --api generates an application.rb file with that specific line commented out. – Vibratile

Answer 2

I was running this command -- out of sheer habit -- in the root of an API-only app, which, of course, has no assets.

Debose

Oh. thank you this saved me. My app was also an API-only application. – Salenasalene

Add me to the list.. – Close

Answer 3

I know this is an old post but I thought it might help someone (probably my future self) if I added this to the answers.

add to Capfile (or deploy.rb)

load 'deploy/assets'

add this to application.rb

require 'sprockets/railtie'

Afterbrain

I'm having the same issue. but on rails 2. i've added these lines but it didn't help (and not to application.rb but to enviroment.rb) – Declare

This fixed it for me on Thin + Rails 3.2 with Mongodb. Thanks!! – Spinifex

Answer 4

I think that it might be because you aren't requiring the asset gems in production. By default rails expects that you are pre-compiling your assets in production. Change this in config/application.rb:

Comment out this line:

Bundler.require *Rails.groups(:assets => %w(development test))

And uncomment this line:

Bundler.require(:default, :assets, Rails.env)

Extragalactic

I'm not a mongoid user like the currently accepted answer mentions in the comments. In my case I had a seperate environment just to precompile assets and the error went away once I added the new environment to the list mentioned in this answer. – Gotama

I had an extremely old app (2008), that doesn't even have sprockets, so this is the answer I needed. Cap defaults to expecting to precompile the asset pipeline, but since there is no asset pipeline it fails. – Foucquet

Answer 5

That's strange. You could always try adding

load "sprockets/assets.rake"

to your Rakefile. It should be included by the actionpack railtie.

My Rakefile contains:

require File.expand_path('../config/application', __FILE__)
Qnm::Application.load_tasks

Galvanize

Answer 6

This worked for me.
Add require "sprockets/railtie" in applications.rb.
And create an empty manifest file app/assets/config/manifest.js

Simas