feat: add postcss loader

.nvmrc

@@ -0,0 +1 @@
+14.9.0

Gemfile

@@ -10,7 +10,7 @@ gem 'pg', '>= 0.18', '< 2.0'
 # Use Puma as the app server
 gem 'puma', '~> 4.1'
 # Transpile app-like JavaScript. Read more: https://github.com/rails/webpacker
-gem 'webpacker', '~> 4.0'
+gem 'webpacker', '~> 5.2'
 # Turbolinks makes navigating your web application faster. Read more: https://github.com/turbolinks/turbolinks
 gem 'turbolinks', '~> 5'
 # Build JSON APIs with ease. Read more: https://github.com/rails/jbuilder

Gemfile.lock

@@ -128,6 +128,7 @@ GEM
     rb-fsevent (0.10.4)
     rb-inotify (0.10.1)
       ffi (~> 1.0)
+    semantic_range (2.3.0)
     spring (2.1.1)
     spring-watcher-listen (2.0.1)
       listen (>= 2.7, < 4.0)
@@ -151,10 +152,11 @@ GEM
       activemodel (>= 6.0.0)
       bindex (>= 0.4.0)
       railties (>= 6.0.0)
-    webpacker (4.3.0)
-      activesupport (>= 4.2)
+    webpacker (5.2.1)
+      activesupport (>= 5.2)
       rack-proxy (>= 0.6.1)
-      railties (>= 4.2)
+      railties (>= 5.2)
+      semantic_range (>= 2.3.0)
     websocket-driver (0.7.3)
       websocket-extensions (>= 0.1.0)
     websocket-extensions (0.1.5)
@@ -176,7 +178,7 @@ DEPENDENCIES
   turbolinks (~> 5)
   tzinfo-data
   web-console (>= 3.3.0)
-  webpacker (~> 4.0)
+  webpacker (~> 5.2)
 
 RUBY VERSION
    ruby 2.7.1p83

config/webpack/environment.js

@@ -1,3 +1,11 @@
-const { environment } = require('@rails/webpacker')
+const { environment } = require("@rails/webpacker");
 
-module.exports = environment
+["css", "moduleCss"].forEach((loaderName) => {
+  const loader = environment.loaders.get(loaderName);
+
+  loader.test = /\.(p?css)$/i;
+
+  environment.loaders.insert(loaderName, loader);
+});
+
+module.exports = environment;

package.json

@@ -5,7 +5,7 @@
     "@rails/actioncable": "^6.0.0",
     "@rails/activestorage": "^6.0.0",
     "@rails/ujs": "^6.0.0",
-    "@rails/webpacker": "4.3.0",
+    "@rails/webpacker": "^5.2.0",
     "turbolinks": "^5.2.0"
   },
   "version": "0.1.0",