在Ruby中读写Unix Socket

Question

我试图在Ruby中连接、读取和写入一个UNIX套接字，这是haproxy使用的统计套接字。

我的代码如下：

require 'socket'
socket = UNIXSocket.new("/tmp/haproxy.stats.socket")

# First attempt: works

socket.puts("show stat")

while(line = socket.gets) do
  puts line
end

# Second attemp: fails

socket.puts("show stat")

while(line = socket.gets) do
  puts line
end

第一次尝试成功，但第二次尝试失败。 我不确定原因。

# pxname,svname,qcur,qmax,scur,smax,slim,stot,bin,bout,dreq,dresp,ereq,econ,eresp,wretr,wredis,status,weight,act,bck,chkfail,chkdown,lastchg,downtime,qlimit,pid,iid,sid,throttle,lbtot,tracked,type,rate,rate_lim,rate_max,check_status,check_code,check_duration,hrsp_1xx,hrsp_2xx,hrsp_3xx,hrsp_4xx,hrsp_5xx,hrsp_other,hanafail,req_rate,req_rate_max,req_tot,cli_abrt,srv_abrt,
stats,FRONTEND,,,0,0,2000,0,0,0,0,0,0,,,,,OPEN,,,,,,,,,1,1,0,,,,0,0,0,0,,,,0,0,0,0,0,0,,0,0,0,,,
stats,BACKEND,0,0,0,0,2000,0,0,0,0,0,,0,0,0,0,UP,0,0,0,,0,22,0,,1,1,0,,0,,1,0,,0,,,,0,0,0,0,0,0,,,,,0,0,
legacy_socket,FRONTEND,,,0,0,1000,0,0,0,0,0,0,,,,,OPEN,,,,,,,,,1,2,0,,,,0,0,0,0,,,,0,0,0,0,0,0,,0,0,0,,,
all,FRONTEND,,,0,0,10000,0,0,0,0,0,0,,,,,OPEN,,,,,,,,,1,3,0,,,,0,0,0,0,,,,0,0,0,0,0,0,,0,0,0,,,
socket_backend,socket,0,0,0,0,200,0,0,0,,0,,0,0,0,0,DOWN,1,1,0,0,1,22,22,,1,4,1,,0,,2,0,,0,L4CON,,0,0,0,0,0,0,0,0,,,,0,0,
socket_backend,socket,0,0,0,0,200,0,0,0,,0,,0,0,0,0,DOWN,1,1,0,0,1,22,22,,1,4,2,,0,,2,0,,0,L4CON,,0,0,0,0,0,0,0,0,,,,0,0,
socket_backend,socket,0,0,0,0,200,0,0,0,,0,,0,0,0,0,DOWN,1,1,0,0,1,22,22,,1,4,3,,0,,2,0,,0,L4CON,,0,0,0,0,0,0,0,0,,,,0,0,
socket_backend,socket,0,0,0,0,200,0,0,0,,0,,0,0,0,0,DOWN,1,1,0,0,1,22,22,,1,4,4,,0,,2,0,,0,L4CON,,0,0,0,0,0,0,0,0,,,,0,0,
socket_backend,socket,0,0,0,0,200,0,0,0,,0,,0,0,0,0,DOWN,1,1,0,0,1,22,22,,1,4,5,,0,,2,0,,0,L4CON,,0,0,0,0,0,0,0,0,,,,0,0,
socket_backend,socket,0,0,0,0,200,0,0,0,,0,,0,0,0,0,DOWN,1,1,0,0,1,22,22,,1,4,6,,0,,2,0,,0,L4CON,,0,0,0,0,0,0,0,0,,,,0,0,
socket_backend,socket,0,0,0,0,200,0,0,0,,0,,0,0,0,0,DOWN,1,1,0,0,1,22,22,,1,4,7,,0,,2,0,,0,L4CON,,0,0,0,0,0,0,0,0,,,,0,0,
socket_backend,socket,0,0,0,0,200,0,0,0,,0,,0,0,0,0,DOWN,1,1,0,0,1,21,21,,1,4,8,,0,,2,0,,0,L4CON,,0,0,0,0,0,0,0,0,,,,0,0,
socket_backend,socket,0,0,0,0,200,0,0,0,,0,,0,0,0,0,DOWN,1,1,0,0,1,21,21,,1,4,9,,0,,2,0,,0,L4CON,,0,0,0,0,0,0,0,0,,,,0,0,
socket_backend,socket,0,0,0,0,200,0,0,0,,0,,0,0,0,0,DOWN,1,1,0,0,1,21,21,,1,4,10,,0,,2,0,,0,L4CON,,0,0,0,0,0,0,0,0,,,,0,0,
socket_backend,BACKEND,0,0,0,0,0,0,0,0,0,0,,0,0,0,0,DOWN,0,0,0,,1,21,21,,1,4,0,,0,,1,0,,0,,,,0,0,0,0,0,0,,,,,0,0,
api_backend,api,0,0,0,0,200,0,0,0,,0,,0,0,0,0,UP,1,1,0,0,0,22,0,,1,5,1,,0,,2,0,,0,L4OK,,0,0,0,0,0,0,0,0,,,,0,0,
api_backend,api,0,0,0,0,1,0,0,0,,0,,0,0,0,0,UP,1,1,0,0,0,22,0,,1,5,2,,0,,2,0,,0,L4OK,,0,0,0,0,0,0,0,0,,,,0,0,
api_backend,api,0,0,0,0,1,0,0,0,,0,,0,0,0,0,DOWN,1,1,0,0,1,21,21,,1,5,3,,0,,2,0,,0,L4CON,,0,0,0,0,0,0,0,0,,,,0,0,
api_backend,BACKEND,0,0,0,0,0,0,0,0,0,0,,0,0,0,0,UP,2,2,0,,0,22,0,,1,5,0,,0,,1,0,,0,,,,0,0,0,0,0,0,,,,,0,0,
www_backend,ruby-www,0,0,0,0,10000,0,0,0,,0,,0,0,0,0,UP,1,1,0,0,0,22,0,,1,6,1,,0,,2,0,,0,L4OK,,0,0,0,0,0,0,0,0,,,,0,0,
www_backend,BACKEND,0,0,0,0,0,0,0,0,0,0,,0,0,0,0,UP,1,1,0,,0,22,0,,1,6,0,,0,,1,0,,0,,,,0,0,0,0,0,0,,,,,0,0,

/Users/Olly/Desktop/haproxy_stats.rb:14:in `write': Broken pipe (Errno::EPIPE)
    from /Users/Olly/Desktop/haproxy_stats.rb:14:in `puts'
    from /Users/Olly/Desktop/haproxy_stats.rb:14

问题是什么？有没有一个很好的参考可以教我如何使用UNIX sockets和Ruby？

- Olly

Answer 1

Olly，

HAproxy在没有使用"prompt"命令的情况下会在第一个请求后关闭连接（请参见http://haproxy.1wt.eu/download/1.4/doc/configuration.txt的9.2部分）：

#!/usr/bin/env ruby                                                                                                                         

require 'socket'                                                                                                                            

socket = UNIXSocket.new("/tmp/haproxy.stats.socket")                                                                                            

# Goes interactive mode
socket.puts("prompt")                                                                                                                       

# Ask statistics every second                                                                                                                             
while true                                                                                                                                  
  socket.puts("show stat")                                                                                                                  
  socket.each_char do |c|
    # We had the prompt, break out                                                                                                   
    break if c == '>'                                                                                                                       
    print c                                                                                                                                 
  end                                                                                                                                       

  sleep 1                                                                                                                                   
end            

- leucos

Answer 2

看起来第一个请求之后连接已经关闭了。我认为你没有做错任何事情。HAProxy状态套接字可能是设计成响应单个命令，然后关闭连接的。

我认为你需要为每个请求重新连接。

如果你看一下这篇博客文章，它是关于使用socat与HAProxy状态套接字，那么这就有意义了，因为你将show stat命令管道传输到socat中，socat从套接字读取直到套接字关闭。

- mikej

---

谢谢。看起来我需要了解一下UNIX套接字的工作原理。我本来以为它会像一个保持打开状态的TCPSocket那样工作。 - Olly

我不太明白的一件事是，当我使用socat时，我总是会从套接字中得到返回结果，但是当我通过上面的Ruby代码运行时，有时我却没有得到任何来自HAproxy的数据返回...所以我不得不运行几次...大概是因为Ruby套接字实现中的一些不靠谱的东西吧。 - milosgajdos

Answer 3

当我使用 socket.puts 时，也遇到了同样的问题，你可以使用 socket.write 来代替 socket.puts 来解决它。

#!/usr/bin/evn ruby
# -*- coding: UTF-8 -*-

require 'rubygems'
require 'uri'
require 'socket'
require 'yaml'

SOCKET = URI.parse("/var/run/haproxy/haproxy.sock")

def get_info
  UNIXSocket.open(SOCKET.path) do |socket|
    socket.write("show info;")
    info = YAML::load socket
    #info.each {|key, value| puts "#{key} ➤ #{value}"}
  end
end

puts get_info["Uptime_sec"]

查看此gem获取更多信息，源代码在这里。

- Terry

Answer 4

你可以使用 man socket。你可以像使用 C 函数一样使用 socket 类。

我发现 man-pages 非常有用。

- Dave