Fix rails restart issue with Puma

- We need to pass the restart command to Puma so that it will use it
  while restarting the server.
- Also made sure that all the options passed by user while starting
  the server are used in the generated restart command so that they will
  be used while restarting the server.
- Besides that we need to remove the server.pid file for the previous running
  server because otherwise Rack complains about it's presence.
- We don't care if the server.pid file does not exist. We only want to delete
  it if it exists.
- This also requires some changes on Puma side which are being tracked
  here - https://github.com/puma/puma/pull/936.
- Fixes #23910.

railties/CHANGELOG.md

@@ -1,3 +1,8 @@
+*   Make `rails restart` command work with Puma by passing the restart command
+    which Puma can use to restart rails server.
+
+    *Prathamesh Sonpatki*
+
 *   The application generator writes a new file `config/spring.rb`, which tells
     Spring to watch additional common files.
 

railties/lib/rails/commands/server.rb

@@ -94,7 +94,8 @@ module Rails
         environment:        (ENV['RAILS_ENV'] || ENV['RACK_ENV'] || "development").dup,
         daemonize:          false,
         caching:            nil,
-        pid:                Options::DEFAULT_PID_PATH
+        pid:                Options::DEFAULT_PID_PATH,
+        restart_cmd:        restart_command
       })
     end
 
@@ -130,5 +131,9 @@ module Rails
           Rails.logger.extend(ActiveSupport::Logger.broadcast(console))
         end
       end
+
+      def restart_command
+        "bin/rails server #{ARGV.join(' ')}"
+      end
   end
 end

railties/lib/rails/dev_caching.rb

@@ -15,6 +15,7 @@ module Rails
         end
 
         FileUtils.touch 'tmp/restart.txt'
+        FileUtils.rm_f('tmp/pids/server.pid')
       end
 
       def enable_by_argument(caching)

railties/lib/rails/tasks/restart.rake

@@ -2,4 +2,5 @@ desc "Restart app by touching tmp/restart.txt"
 task :restart do
   FileUtils.mkdir_p('tmp')
   FileUtils.touch('tmp/restart.txt')
+  FileUtils.rm_f('tmp/pids/server.pid')
 end

railties/test/application/rake/dev_test.rb

@@ -29,6 +29,15 @@ module ApplicationTests
           assert_match(/Development mode is no longer being cached/, output)
         end
       end
+
+      test 'dev:cache removes server.pid also' do
+        Dir.chdir(app_path) do
+          FileUtils.mkdir_p("tmp/pids")
+          FileUtils.touch("tmp/pids/server.pid")
+          `rake dev:cache`
+          assert_not File.exist?("tmp/pids/server.pid")
+        end
+      end
     end
   end
 end

railties/test/application/rake/restart_test.rb

@@ -34,6 +34,15 @@ module ApplicationTests
           assert File.exist?('tmp/restart.txt')
         end
       end
+
+      test 'rake restart removes server.pid also' do
+        Dir.chdir(app_path) do
+          FileUtils.mkdir_p("tmp/pids")
+          FileUtils.touch("tmp/pids/server.pid")
+          `rake restart`
+          assert_not File.exist?("tmp/pids/server.pid")
+        end
+      end
     end
   end
 end

railties/test/commands/server_test.rb

@@ -118,4 +118,18 @@ class Rails::ServerTest < ActiveSupport::TestCase
       assert_equal old_default_options, server.default_options
     end
   end
+
+  def test_restart_command_contains_customized_options
+    original_args = ARGV.dup
+    args = ["-p", "4567"]
+    ARGV.replace args
+
+    options = Rails::Server::Options.new.parse! args
+    server = Rails::Server.new options
+    expected = "bin/rails server -p 4567"
+
+    assert_equal expected, server.default_options[:restart_cmd]
+  ensure
+    ARGV.replace original_args
+  end
 end