rails tailwindcss:watch issue on Windows 10 / Sprockets::Rails::Helper::AssetNotPrecompiledError

[allanclloyds]

I don't know if this is a tailwindcss-rails issue or something else - I'm a bit rusty as a Rails dev now, but hopefully this issue helps someone else as a workaround.

A fresh install of Rails 7 on Ruby 2.7.5 x64-mingw32 (Windows 10) with --css=tailwind and slim templates gives Sprockets::Rails::Helper::AssetNotPrecompiledError in development.

Asset `tailwind.css` was not declared to be precompiled in production.
Declare links to your assets in `app/assets/config/manifest.js`.

  //= link tailwind.css

and restart your server

application.html.slim:

html
  head
    = csrf_meta_tags
    = csp_meta_tag
    meta name="viewport" content="width=device-width, initial-scale=1.0"
    = stylesheet_link_tag "tailwind", "inter-font", "data-turbo-track": "reload"
    = stylesheet_link_tag "application", "data-turbo-track": "reload"
    = javascript_importmap_tags

bin/dev is a bash script and doesn't run on Windows, but it just installs and runs foreman.

foreman start -f Procfile.dev throws an error

C:/Ruby27-x64/lib/ruby/gems/2.7.0/gems/foreman-0.87.2/lib/foreman/process.rb:54:in `spawn': Exec format error - bin/rails server -p 3000 (Errno::ENOEXEC)

rails tailwindcss:watch runs and quits without an error and without building tailwind.css

The workaround is to manually run tailwindcss -i app/assets/stylesheets/application.tailwind.css -o app/assets/builds/tailwind.css -c config/tailwind.config.js -w which works okay, and builds tailwind.css in app/assets/builds so the app doesn't throw an exception.

[jsvcycling]

Running foreman manually fails for the same reason you can't run bin/dev (Windows doesn't understand how to run bin/rails) so that's not surprising.

It should also be noted that the suggested action by Rails (adding //= link tailwind.css) get the project running but using the vanilla TailwindCSS configuration; anything setup in config/tailwind.config.js isn't used. So it's definitely not the "correct" resolution.

[pietmichal]

I'm experiencing the same problem with Windows 10.

The workaround removed the error.

[pietmichal]

I've modified the gem on my machine so the rake build task (lib/tasks/build.rake) prepends ruby to tailwind compile command.

TAILWIND_COMPILE_COMMAND = "#{Pathname.new(__dir__).to_s}/../../exe/tailwindcss -i #{Rails.root.join("app/assets/stylesheets/application.tailwind.css")} -o #{Rails.root.join("app/assets/builds/tailwind.css")} -c #{Rails.root.join("config/tailwind.config.js")} --minify"

namespace :tailwindcss do
  desc "Build your Tailwind CSS"
  task :build do
    system "ruby " + TAILWIND_COMPILE_COMMAND
  end

  desc "Watch and build your Tailwind CSS on file changes"
  task :watch do
    system "ruby #{TAILWIND_COMPILE_COMMAND} -w"
  end
end

Rake::Task["assets:precompile"].enhance(["tailwindcss:build"])

if Rake::Task.task_defined?("test:prepare")
  Rake::Task["test:prepare"].enhance(["tailwindcss:build"])
elsif Rake::Task.task_defined?("db:test:prepare")
  Rake::Task["db:test:prepare"].enhance(["tailwindcss:build"])
end

Now, rails tailwindcss:build works as expected.