"Expected to find a manifest file" error with assets disabled

[delner]

With the release of Sprockets 4.0 and the requirement of a manifest.js file, we're seeing an error similar to #443 with sprockets-rails 3.2.1 where our test suite is producing this error:

/usr/local/bundle/gems/sprockets-rails-3.2.1/lib/sprockets/railtie.rb:105:in `block in <class:Railtie>': Expected to find a manifest file in `app/assets/config/manifest.js` (Sprockets::Railtie::ManifestNeededError)
But did not, please create this file and use it to link any assets that need
to be rendered by your app:

Example:
  //= link_tree ../images
  //= link_directory ../javascripts .js
  //= link_directory ../stylesheets .css
and restart your server

We load the standard require 'rails/all' in our test suite (which loads sprockets 4.0 by default), but we have no interest in using Sprockets or the asset pipeline within it.

If we disable Sprockets with config.assets.enabled = false in our application, we expect that we shouldn't need to have a manifest.js file. However, merely having require 'sprockets/railtie' anywhere in your application will force this check to occur unconditionally, regardless of if you've disabled the the application pipeline:

https://github.com/rails/sprockets-rails/blob/v3.2.1/lib/sprockets/railtie.rb#L103-L110

initializer :set_default_precompile do |app|
  if using_sprockets4?
    raise ManifestNeededError unless ::Rails.root.join("app/assets/config/manifest.js").exist?
    app.config.assets.precompile += %w( manifest.js )
  else
    app.config.assets.precompile += [LOOSE_APP_ASSETS, /(?:\/|\\|\A)application\.(css|js)$/]
  end
end

I would suggest changing this check to be based conditionally on whether assets are enabled or not, so users are not forced to completely remove sprocket-rails to disable it.

[rafaelfranca]

The proper way to fix this is stop using require 'rails/all' and not load sprockets/rails in your application.

[delner]

This is not a good option for us; we need all the default Rails components other than Sprockets, and to have to update our require '*/railtie' statements every time Rails adds new components (e.g. ActionText, ActionMailbox) because sprockets-rails doesn't check whether its actually enabled or not seems like a bad experience for Rails users who gem 'rails'.

[rafaelfranca]

The way Rails let you opt-out components is by requiring individual railties. Railties are added once a year, you don't need a lot of work to add require statements once a year. There is no other option, sorry.

[delner]

If preventing require 'sprockets/railtie' (from being loaded as a part of require 'rails/all') is the only way to disable Sprockets, then what is the purpose of config.assets.enabled = false?

[rafaelfranca]

That is for disabling compilation of assets. That doesn't disable the sprockets-rails to be loaded or executed.

[matthewmath]

Just curious, the path is sprockets 3.2.1, why is using_sprockets4? now returning true and dropping into the required manifest code?

[rafaelfranca]

sprockets is different of sprockets-rails. The path is sprockets-rails-3.2.1

[denys-husiev]

I have this error just because I need to require 'sprockets/railtie' for using graphiql-rails gem. And to fix it, I should add manifest.js file to my rails api project. Seems a little weird :)

[hugoh59]

How do you solve this error?

[andreynering]

I could solve it by running:

mkdir -p app/assets/config && echo '{}' > app/assets/config/manifest.js

[joelcahalan]

I had to pin an API only rails app to sprockets less than 4. Despite not requiring sprockets in application.rb it was still somehow being loaded and causing an error.

[sobrinho]

Got bitten by this one more time today.

[swapnilchincholkar]

Faced the same issue with API only app with rails(v 6.0.3.3), ruby(v 2.7.1). Required to do both of the following,

1. Uncommented require "sprockets/railtie" from config/application.rb
2. And creating empty manifest file as said by @andreynering

[mayankdedhia]

An alternative approach to avoiding this issue would be to lock sprockets-rails to pre 4.x by explicitly adding to your Gemfile:

gem "sprockets", "<4"

Judging by the gemspec, Rails 6.0 is still compatible with both sprockets 2.x and 3.x.

Just doing this worked for my API only app

[gingerlime]

sorry for another "me too", but I'm really confused why this happens even for a rails app that doesn't use sprockets any more. We:

• removed the gem (sprockets / sprockets-rails are both removed from our Gemfile)
• remove require "rails/all"
• commented out require "sprockets/railtie"
• removed our manifest.json since we no longer use it

Normally rails runs fine, but when we run, e.g. bundle exec rake db:test:prepare we get this error because the manifest.json is missing

I understand the workaround with an empty json file, but this still means that some process is running / checking this file, when it shouldn't if sprockets is disabled. Right?

EDIT: it seems to happen after we upgraded rails. So even though we don't have sprockets/sprockets-rails in our Gemfile, it's installed as a dependency, and then we get this issue because there's no manifest.json file. Using the workaround seems ok for now, but rather strange.

[omarsotillo]

I know this is closed but I found kind of the issue at least for me ( I was upgrading from 5.2 to 6.0 and swap into webpacker) !

After digging into it it was related with sassc rails. It is using sprockets under the hood

My approach:

• Remove sassc-rails or find alternative
• Remove all references to assets
• Remove tmp/assets folder
• Remove app/assets

Maybe it works for some of you :)

cc @gingerlime @mayankdedhia @swapnilchincholkar

[omarsotillo]

Also recommended by @ahorek here (did not try myself)

just change

//= require applicationtest.sass
to

//= require applicationtest

[yonyossef]

Expected to find a manifest file in `app/assets/config/manifest.js` (Sprockets::Railtie::ManifestNeededError)
But did not, please create this file and use it to link any assets that need

Hi, can anyone tell me if the manifest.js file link is hard coded in sprockets, or it can be changed to a different location?
Can I change it from app/assets/config/manifest.js to lib/assets?
Thx

[kevinmtrowbridge]

This monkeypatch will allow the behavior to be changed (perhaps introducing other problems ... use only after thinking about the tradeoffs):

module Sprockets
  class Railtie < ::Rails::Railtie
    initializer :set_default_precompile_manifest_optional, after: :set_default_precompile do |app|
      # Find original method here: https://github.com/rails/sprockets-rails/blob/master/lib/sprockets/railtie.rb#L103
      p "sprockets_monkeypatch_make_manifest_optional.rb"
      app.config.assets.precompile += %w( manifest.js )
    end
    # https://dev.to/st0012/how-to-replace-a-rails-initializer-30n0
    initializers.reject! { |i| i.name == :set_default_precompile }
  end
end