当运行 Sinatra 在已占用的端口上时避免显示回溯

Question

当 Sinatra 无法正确运行服务器（例如，由于端口已被使用）时，阻止 Sinatra 显示完整回溯的正确方法是什么？

这是一个示例 sinatra 应用程序：

# test.rb
require 'sinatra'
require 'bundler/inline'

gemfile do
  gem 'sinatra'
  gem 'puma'
end

set :bind, "0.0.0.0"
set :port, 3000

get '/' do
  "hello"
end

然后运行与ruby test.rb连接一次，占用端口

然后，运行在另一个终端中再次使用它 window，并显示完整的错误回溯：

$ ruby test.rb
== Sinatra (v2.0.4) has taken the stage on 3000 for development with backup from Puma
Puma starting in single mode...
* Version 3.12.0 (ruby 2.5.0-p0), codename: Llamas in Pajamas
* Min threads: 0, max threads: 16
* Environment: development
* Listening on tcp://0.0.0.0:3000
== Someone is already performing on port 3000!
Traceback (most recent call last):
        5: from /store/gems/ruby-2.5.0/gems/sinatra-2.0.4/lib/sinatra/main.rb:26:in `block in <module:Sinatra>'
        4: from /store/gems/ruby-2.5.0/gems/sinatra-2.0.4/lib/sinatra/base.rb:1464:in `run!'
        3: from /store/gems/ruby-2.5.0/gems/sinatra-2.0.4/lib/sinatra/base.rb:1464:in `ensure in run!'
        2: from /store/gems/ruby-2.5.0/gems/sinatra-2.0.4/lib/sinatra/base.rb:1439:in `quit!'
        1: from /store/gems/ruby-2.5.0/gems/puma-3.12.0/lib/puma/launcher.rb:147:in `stop'
/store/gems/ruby-2.5.0/gems/puma-3.12.0/lib/puma/single.rb:27:in `stop': undefined method `stop' for nil:NilClass (NoMethodError)
Traceback (most recent call last):
        3: from /store/gems/ruby-2.5.0/gems/sinatra-2.0.4/lib/sinatra/base.rb:1545:in `block in setup_traps'
        2: from /store/gems/ruby-2.5.0/gems/sinatra-2.0.4/lib/sinatra/base.rb:1439:in `quit!'
        1: from /store/gems/ruby-2.5.0/gems/puma-3.12.0/lib/puma/launcher.rb:147:in `stop'
/store/gems/ruby-2.5.0/gems/puma-3.12.0/lib/puma/single.rb:27:in `stop': undefined method `stop' for nil:NilClass (NoMethodError)

因为我将它用作嵌入式服务器，所以我希望输出简单并且带有 Sinatra 已经显示的友好错误：

== Someone is already performing on port 3000!

并避免显示回溯。

Answer 1

Ruby 默认输出错误信息到 STDOUT。但是如果你在 *nix 系统上，你可以这样做：

ruby test.rb > /dev/null 2>&1

对于windows你大概可以做到

ruby test.rb > NULL

windows powershell

ruby test.rb > $null

但对于 windows 另见 Is there a /dev/null on Windows?

但是如果你想在服务器为运行时以编程方式抑制输出，这应该适用于 *nix 但不确定 windows

# test.rb
require 'sinatra'
require 'bundler/inline'

gemfile do
  gem 'sinatra'
  gem 'puma'
end

set :bind, "0.0.0.0"
set :port, 3000

get '/' do
  "hello"
end

unless `ps aux | grep sinatra`.match('tcp://0.0.0.0:3000')
  STDOUT.reopen('/dev/null', 'w')
  STDERR.reopen('/dev/null', 'w')
end

见suppresing output to console with ruby

Answer 2

您可以通过在允许 Sinatra 和 Puma 接管之前尝试侦听端口来测试端口是否正在使用。这不是 100% 有效，因为存在竞争条件，您可以打开和关闭端口，但在 Sinatra/Puma 完成初始化之前，一些其他进程出现并侦听同一端口，但它应该适合您使用 -案例（这似乎只是一个装饰黑客）。

在 test.rb 中的任意位置插入此代码：

require 'socket'
include Socket::Constants

begin
  # Open and close the port
  socket = Socket.new(AF_INET, SOCK_STREAM, 0)
  sockaddr = Socket.pack_sockaddr_in(3000, '0.0.0.0')
  socket.bind(sockaddr)
  socket.listen(1)
  socket.close
rescue Errno::EADDRINUSE => error
  # Traps the same error that is trapped by Sinatra and exits if raised
  puts error.message
  exit
end

第一个开始 ruby test.rb:

== Sinatra (v2.0.4) has taken the stage on 3000 for development with backup from Puma
Puma starting in single mode...
* Version 3.12.0 (ruby 2.6.0-p-1), codename: Llamas in Pajamas
* Min threads: 0, max threads: 16
* Environment: development
* Listening on tcp://0.0.0.0:3000
Use Ctrl-C to stop

第二个开始 ruby test.rb:

Address already in use - bind(2) for 0.0.0.0:3000

您可以在 rescue 块内充实您想要打印到控制台的内容。

Answer 3

这似乎是由 issue with Puma, that is fixed by this PR 引起的。

当 运行 Sinatra 在已占用的端口上时避免显示回溯

Avoid display of backtrace when running Sinatra on an already taken port

ruby

sinatra

当运行 Sinatra 在已占用的端口上时避免显示回溯