haproxy使用总结

DESCRIPTION
       HAProxy is a TCP/HTTP reverse proxy which is particularly suited for high availability environments.  Indeed,  it
       can:
        - route HTTP requests depending on statically assigned cookies ;
        - spread the load among several servers while assuring server
          persistence through the use of HTTP cookies ;
        - switch to backup servers in the event a main one fails ;
        - accept connections to special ports dedicated to service
          monitoring ;
        - stop accepting connections without breaking existing ones ;
        - add/modify/delete HTTP headers both ways ;
        - block requests matching a particular pattern ;
        - hold clients to the right application server depending on
          application cookies
        - report detailed status as HTML pages to authenticated users from an
          URI intercepted from the application.

       It needs very little resource. Its event-driven architecture allows it to easily handle thousands of simultaneous
       connections on hundreds of instances without risking the system's stability.

• 负载均衡

   global
          daemon
          maxconn 256
  
      defaults
          mode tcp
          timeout connect 5000ms
          timeout client 50000ms
          timeout server 50000ms
  
      frontend testhost
          bind *:1998
          default_backend servers
  
      backend servers
          server server52 127.0.0.1:52 check
          server server872 127.0.0.1:872 check
          server server42 127.0.0.1:42 check
          retries 3
          redispatch
  

   
• 灾难备份

  global
          daemon
          maxconn 256
          log 127.0.0.1   local3
          pidfile /tmp/haproxy.pid
          #stats socket /tmp/haproxy_1.5_dev_11.stats.socket
  
  
      defaults
          mode tcp
          timeout connect 5000ms
          timeout client 50000ms
          timeout server 50000ms
          log     127.0.0.1       local3
          option log-health-checks
  
  
      frontend testhost
          bind *:1998
          default_backend servers
  
      backend servers
          server server52 127.0.0.1:52 check
          server server872 127.0.0.1:872 check backup
  

   
• 热启动(修改config让程序立即生效）
  

  #!/bin/bash
  #haproxy_hot_reload_config.sh
  #the program will restart the haproxy by using  its hot reconfiguration
  
  config=" /home/prj/haproxy_conf/haproxy.cfg.mysql212"
  pidfile=`grep pidfile $config | awk  '{print   $2}'`
  pid=`cat $pidfile`
  status=-2
  
  if [ -e /proc/$pid/exe ]; then
     /usr/local/sbin/haproxy -D -f  $config -sf $pid
     status=0
  else
     /usr/local/sbin/haproxy -D -f  $config
     status=1
  fi
  
  echo $status
  exit $status