add support to configure the number of web workers for puma

lib/kuby/docker/webserver_phase.rb

@@ -28,7 +28,7 @@ class Puma < Webserver
         def apply_to(dockerfile)
           dockerfile.cmd(
             'puma',
-            '--workers', '4',
+            '--workers', phase.workers.to_s,
             '--bind', 'tcp://0.0.0.0',
             '--port', phase.port.to_s,
             '--pidfile', './server.pid',
@@ -40,11 +40,15 @@ def apply_to(dockerfile)
       end
 
       DEFAULT_PORT = T.let(8080, Integer)
+      DEFAULT_WORKERS = T.let(4, Integer)
       WEBSERVER_MAP = T.let({ puma: Puma }.freeze, T::Hash[Symbol, T.class_of(Webserver)])
 
       T::Sig::WithoutRuntime.sig { params(port: Integer).returns(Integer) }
       attr_writer :port
 
+      T::Sig::WithoutRuntime.sig { params(port: Integer).returns(Integer) }
+      attr_writer :workers
+
       T::Sig::WithoutRuntime.sig { returns(T.nilable(Symbol)) }
       attr_reader :webserver
 
@@ -56,6 +60,7 @@ def initialize(environment)
         super
 
         @port = T.let(@port, T.nilable(Integer))
+        @workers = T.let(@workers, T.nilable(Integer))
         @webserver = T.let(@webserver, T.nilable(Symbol))
       end
 
@@ -73,6 +78,10 @@ def port
         @port || DEFAULT_PORT
       end
 
+      def workers
+        @workers || DEFAULT_WORKERS
+      end
+
       private
 
       T::Sig::WithoutRuntime.sig { returns(T.nilable(Symbol)) }