Move application.tailwind.css to a dir ignored by propshaft

README.md

@@ -101,9 +101,11 @@ Then, run the `tailwindcss:upgrade` task. Among other things, this will try to r
 Here's what the upgrade task does:
 
 - Cleans up some things in the generated `config/tailwind.config.js`.
-- Runs the upstream upgrader (note: requires `npx` to run the one-time upgrade, but highly recommended).
-- Removes references to the Inter font from the application layout.
 - If present, moves `config/postcss.config.js` to the root directory.
+- If present, moves `app/assets/stylesheets/application.tailwind.css` to `app/assets/tailwind`.
+- Removes unnecessary `stylesheet_link_tag "tailwindcss"` tags from the application layout.
+- Removes references to the Inter font from the application layout.
+- Runs the upstream upgrader (note: requires `npx` to run the one-time upgrade, but highly recommended).
 
 Here's what that upgrade looks like on a vanilla Rails app:
 
@@ -112,29 +114,34 @@ $ bin/rails tailwindcss:upgrade
        apply  /path/to/tailwindcss-rails/lib/install/upgrade_tailwindcss.rb
   Removing references to 'defaultTheme' from /home/user/myapp/config/tailwind.config.js
         gsub    config/tailwind.config.js
+  Strip Inter font CSS from application layout
+        gsub    app/views/layouts/application.html.erb
+  Remove unnecessary stylesheet_link_tag from application layout
+        gsub    app/views/layouts/application.html.erb
+  Moving application.tailwind.css to /home/user/myapp/app/assets/tailwind
+      create    app/assets/tailwind/application.tailwind.css
+      remove    app/assets/stylesheets/application.tailwind.css
+10.9.0
   Running the upstream Tailwind CSS upgrader
          run    npx @tailwindcss/upgrade@next --force --config /home/user/myapp/config/tailwind.config.js from "."
 ≈ tailwindcss v4.0.0
 │ Searching for CSS files in the current directory and its subdirectories…
-│ ↳ Linked `./config/tailwind.config.js` to `./app/assets/stylesheets/application.tailwind.css`
+│ ↳ Linked `./config/tailwind.config.js` to `./app/assets/tailwind/application.tailwind.css`
 │ Migrating JavaScript configuration files…
 │ ↳ The configuration file at `./config/tailwind.config.js` could not be automatically migrated to the new CSS
 │   configuration format, so your CSS has been updated to load your existing configuration file.
 │ Migrating templates…
 │ ↳ Migrated templates for configuration file: `./config/tailwind.config.js`
 │ Migrating stylesheets…
-│ ↳ Migrated stylesheet: `./app/assets/stylesheets/application.tailwind.css`
+│ ↳ Migrated stylesheet: `./app/assets/tailwind/application.tailwind.css`
 │ ↳ No PostCSS config found, skipping migration.
 │ Updating dependencies…
 │ Could not detect a package manager. Please manually update `tailwindcss` to v4.
 │ Verify the changes and commit them to your repository.
-  Strip Inter font CSS from application layout
-        gsub    app/views/layouts/application.html.erb
   Compile initial Tailwind build
          run    rails tailwindcss:build from "."
 ≈ tailwindcss v4.0.0
-
-Done in 52ms
+Done in 56ms
          run  bundle install --quiet
 ```
 
@@ -157,9 +164,11 @@ We'll try to improve the upgrade process over time, but for now you may need to
 
 ### Configuration and commands
 
-#### Input file: `app/assets/stylesheets/application.tailwind.css`
+#### Input file: `app/assets/tailwind/application.tailwind.css`
+
+The `tailwindcss:install` task will generate a Tailwind input file in `app/assets/tailwind/application.tailwind.css`. This is where you import the plugins you want to use and where you can setup your custom `@apply` rules.
 
-The installer will generate a Tailwind input file in `app/assets/stylesheets/application.tailwind.css`. This is where you import the plugins you want to use and where you can setup your custom `@apply` rules.
+⚠ The location of this file changed in v4, from `app/assets/stylesheets` to `app/assets/tailwind`. The `tailwindcss:upgrade` task will move it for you.
 
 #### Output file: `app/assets/builds/tailwind.css`
 
@@ -335,17 +344,6 @@ The inline version also works:
 <section class="bg-[url('image.svg')]">Has the image as it's background</section>
 ```
 
-### Conflict with pre-existing asset pipeline stylesheets
-
-If you get a warning `Unrecognized at-rule or error parsing at-rule ‘@tailwind’.` in the browser console after installation, you are incorrectly double-processing `application.tailwind.css`. This is a misconfiguration, even though the styles will be fully effective in many cases.
-
-The file `application.tailwind.css` is installed when running `rails tailwindcss:install` and is placed alongside the common `application.css` in `app/assets/stylesheets`. Because the `application.css` in a newly generated Rails app includes a `require_tree .` directive, the asset pipeline incorrectly processes `application.tailwind.css`, where it should be taken care of by `tailwindcss`. The asset pipeline ignores TailwindCSS's at-directives, and the browser can't process them.
-
-To fix the warning, you can either remove the `application.css`, if you don't plan to use the asset pipeline for stylesheets, and instead rely on TailwindCSS completely for styles. This is what this installer assumes.
-
-Or, if you do want to keep using the asset pipeline in parallel, make sure to remove the `require_tree .` line from the `application.css`.
-
-
 ## License
 
 Tailwind for Rails is released under the [MIT License](https://opensource.org/licenses/MIT).

lib/install/install_tailwindcss.rb

@@ -1,5 +1,6 @@
 APPLICATION_LAYOUT_PATH             = Rails.root.join("app/views/layouts/application.html.erb")
 CENTERING_CONTAINER_INSERTION_POINT = /^\s*<%= yield %>/.freeze
+TAILWIND_ASSET_PATH                 = Rails.root.join("app/assets/tailwind")
 
 if APPLICATION_LAYOUT_PATH.exist?
   unless File.read(APPLICATION_LAYOUT_PATH).match?(/stylesheet_link_tag :app/)
@@ -31,9 +32,9 @@
   append_to_file(".gitignore", %(\n/app/assets/builds/*\n!/app/assets/builds/.keep\n))
 end
 
-unless Rails.root.join("app/assets/stylesheets/application.tailwind.css").exist?
-  say "Add default app/assets/stylesheets/application.tailwind.css"
-  copy_file "#{__dir__}/application.tailwind.css", "app/assets/stylesheets/application.tailwind.css"
+unless TAILWIND_ASSET_PATH.join("application.tailwind.css").exist?
+  say "Add default #{TAILWIND_ASSET_PATH}/application.tailwind.css"
+  copy_file "#{__dir__}/application.tailwind.css", TAILWIND_ASSET_PATH.join("application.tailwind.css")
 end
 
 if Rails.root.join("Procfile.dev").exist?

lib/install/upgrade_tailwindcss.rb

@@ -1,6 +1,8 @@
 TAILWIND_CONFIG_PATH = Rails.root.join("config/tailwind.config.js")
 APPLICATION_LAYOUT_PATH = Rails.root.join("app/views/layouts/application.html.erb")
 POSTCSS_CONFIG_PATH = Rails.root.join("config/postcss.config.js")
+OLD_TAILWIND_ASSET_PATH = Rails.root.join("app/assets/stylesheets")
+TAILWIND_ASSET_PATH = Rails.root.join("app/assets/tailwind")
 
 unless TAILWIND_CONFIG_PATH.exist?
   say "Default tailwind.config.js is missing!", :red
@@ -14,27 +16,34 @@
 
 if POSTCSS_CONFIG_PATH.exist?
   say "Moving PostCSS configuration to application root directory"
-  FileUtils.mv(POSTCSS_CONFIG_PATH, Rails.root, verbose: true) || abort
+  copy_file POSTCSS_CONFIG_PATH, Rails.root.join("postcss.config.js")
+  remove_file POSTCSS_CONFIG_PATH
 end
 
 if APPLICATION_LAYOUT_PATH.exist?
-  if File.read(APPLICATION_LAYOUT_PATH).match?(/stylesheet_link_tag :app/) &&
-     File.read(APPLICATION_LAYOUT_PATH).match?(/stylesheet_link_tag "tailwind"/)
-    say "Remove unnecessary stylesheet_link_tag from application layout"
-    gsub_file APPLICATION_LAYOUT_PATH.to_s, %r{^\s*<%= stylesheet_link_tag "tailwind".*%>$}, ""
-  end
-
   if File.read(APPLICATION_LAYOUT_PATH).match?(/"inter-font"/)
     say "Strip Inter font CSS from application layout"
     gsub_file APPLICATION_LAYOUT_PATH.to_s, %r{, "inter-font"}, ""
   else
     say "Inter font CSS not detected.", :green
   end
+
+  if File.read(APPLICATION_LAYOUT_PATH).match?(/stylesheet_link_tag :app/) &&
+     File.read(APPLICATION_LAYOUT_PATH).match?(/stylesheet_link_tag "tailwind"/)
+    say "Remove unnecessary stylesheet_link_tag from application layout"
+    gsub_file APPLICATION_LAYOUT_PATH.to_s, %r{^\s*<%= stylesheet_link_tag "tailwind".*%>$}, ""
+  end
 else
   say "Default application.html.erb is missing!", :red
   say %(        Please check your layouts and remove any "inter-font" stylesheet links.)
 end
 
+if OLD_TAILWIND_ASSET_PATH.join("application.tailwind.css").exist?
+  say "Moving application.tailwind.css to #{TAILWIND_ASSET_PATH}"
+  copy_file OLD_TAILWIND_ASSET_PATH.join("application.tailwind.css"), TAILWIND_ASSET_PATH.join("application.tailwind.css")
+  remove_file OLD_TAILWIND_ASSET_PATH.join("application.tailwind.css")
+end
+
 if system("npx --version")
   say "Running the upstream Tailwind CSS upgrader"
   command = Shellwords.join(["npx", "@tailwindcss/upgrade@next", "--force", "--config", TAILWIND_CONFIG_PATH.to_s])

lib/tailwindcss/commands.rb

@@ -8,7 +8,7 @@ def compile_command(debug: false, **kwargs)
 
         command = [
           Tailwindcss::Ruby.executable(**kwargs),
-          "-i", rails_root.join("app/assets/stylesheets/application.tailwind.css").to_s,
+          "-i", rails_root.join("app/assets/tailwind/application.tailwind.css").to_s,
           "-o", rails_root.join("app/assets/builds/tailwind.css").to_s,
         ]
 

lib/tailwindcss/engine.rb

@@ -6,6 +6,12 @@ class Engine < ::Rails::Engine
       Rails.application.config.generators.stylesheets = false
     end
 
+    initializer "tailwindcss.exclude_asset_path", after: "propshaft.append_assets_path" do
+      if Rails.application.config.assets.excluded_paths # the app may not be using Propshaft
+        Rails.application.config.assets.excluded_paths << Rails.root.join("app/assets/tailwind")
+      end
+    end
+
     config.app_generators do |g|
       g.template_engine :tailwindcss
     end

test/integration/user_install_test.sh

@@ -37,7 +37,7 @@ bin/rails tailwindcss:install
 
 # TEST: tailwind was installed correctly
 grep -q "<main class=\"container" app/views/layouts/application.html.erb
-test -a app/assets/stylesheets/application.tailwind.css
+test -a app/assets/tailwind/application.tailwind.css
 
 # TEST: rake tasks don't exec (#188)
 cat <<EOF >> Rakefile
@@ -46,7 +46,7 @@ task :still_here do
 end
 EOF
 
-cat >> app/assets/stylesheets/application.tailwind.css <<EOF
+cat >> app/assets/tailwind/application.tailwind.css <<EOF
 @theme { --color-special: #abc12399; }
 EOF
 

test/integration/user_upgrade_test.sh

@@ -75,10 +75,12 @@ if grep -q inter-font app/views/layouts/application.html.erb ; then
 fi
 
 # TEST: moving the postcss file
-if [ ! -f postcss.config.js ] ; then
-  echo "FAIL: postcss.config.js not moved"
-  exit 1
-fi
+test ! -a config/postcss.config.js
+test   -a postcss.config.js
+
+# TEST: moving application.tailwind.css
+test ! -a app/assets/stylesheets/application.tailwind.css
+test   -a app/assets/tailwind/application.tailwind.css
 
 # generate CSS
 bin/rails tailwindcss:build[verbose]