Support webpacker live-reloading on Docker (#26419)

.devcontainer/docker-compose.yml

@@ -25,6 +25,7 @@ services:
     command: sleep infinity
     ports:
       - '127.0.0.1:3000:3000'
+      - '127.0.0.1:3035:3035'
       - '127.0.0.1:4000:4000'
     networks:
       - external_network

Procfile.dev

@@ -1,4 +1,4 @@
 web: env PORT=3000 RAILS_ENV=development bundle exec puma -C config/puma.rb
 sidekiq: env PORT=3000 RAILS_ENV=development bundle exec sidekiq
 stream: env PORT=4000 yarn run start
-webpack: ./bin/webpack-dev-server --listen-host 0.0.0.0
+webpack: bin/webpack-dev-server

config/initializers/content_security_policy.rb

@@ -34,7 +34,8 @@ Rails.application.config.content_security_policy do |p|
   p.worker_src      :self, :blob, assets_host
 
   if Rails.env.development?
-    webpacker_urls = %w(ws http).map { |protocol| "#{protocol}#{Webpacker.dev_server.https? ? 's' : ''}://#{Webpacker.dev_server.host_with_port}" }
+    webpacker_public_host = ENV.fetch('WEBPACKER_DEV_SERVER_PUBLIC', Webpacker.config.dev_server[:public])
+    webpacker_urls = %w(ws http).map { |protocol| "#{protocol}#{Webpacker.dev_server.https? ? 's' : ''}://#{webpacker_public_host}" }
 
     p.connect_src :self, :data, :blob, assets_host, media_host, Rails.configuration.x.streaming_api_base_url, *webpacker_urls
     p.script_src  :self, :unsafe_inline, :unsafe_eval, assets_host

config/webpacker.yml

@@ -58,7 +58,7 @@ development:
   # Reference: https://webpack.js.org/configuration/dev-server/
   dev_server:
     https: false
-    host: localhost
+    host: 0.0.0.0
     port: 3035
     public: localhost:3035
     hmr: false