如何使用Rails/Puma为404未找到的页面设置HTTP标头

gem 'puma'

# 设置Puma的工作线程数和进程数
threads_count = ENV.fetch("RAILS_MAX_THREADS") { 5 }.to_i
workers_count = ENV.fetch("WEB_CONCURRENCY") { 2 }.to_i

# 允许Puma预加载应用程序，加快启动速度
preload_app!

# 定义Puma工作进程的数量
workers workers_count

# 定义Puma工作线程的数量
threads threads_count, threads_count

# 在Puma启动时执行代码块
on_worker_boot do
  ActiveRecord::Base.establish_connection if defined?(ActiveRecord)
end

# 在Puma关闭时执行代码块
on_restart do
  ActiveRecord::Base.connection_pool.disconnect! if defined?(ActiveRecord)
end

# 监听指定的地址和端口
bind 'tcp://0.0.0.0:3000'

# 如果需要启用SSL，请在这里配置SSL证书和私钥

# 设置404未找到页面的HTTP标头
if defined?(ActiveRecord)
  ActiveRecord::Base.connection_pool.with_connection do
    not_found_app = -> (env) {
      [404, { 'Content-Type' => 'text/html' }, ['Not Found']]
    }

    Rails.application.config.middleware.insert_after ActionDispatch::DebugExceptions, ActionDispatch::ShowExceptions, not_found_app
  end
end