HAproxy 503 Service Unavailable 没有可用的服务器来处理这个请求

Question

我是这种负载平衡方案的新手，我的任务是弄清楚如何使这种负载平衡起作用。

我的环境：

Centos 6.4 64 Bit
Webserver: Lighttpd
All running in ESXI
virtual IP: 192.168.1.6
LB1: 192.168.1.4
LB2: 192.168.1.5
Webserver 1: 192.168.1.12
Webserver 2: 192.168.1.13
Gateway: 192.168.1.1

尝试在使用 HAproxy 和 keepalived 生产之前在实验室中运行测试。这是我的 keepalived 设置：

！keepalived的配置文件

global_defs {
   notification_email {
     myemail@gmail.com
   }
   notification_email_from keepalived@domain.local
   smtp_server 192.168.1.4
   smtp_connect_timeout 30
   router_id 192.168.1.1
}

vrrp_script chk_haproxy {
script "killall -0 haproxy"
interval 1                     # check every second
weight 2                       # add 2 points of prio if OK
}

vrrp_instance VI_1 {
    state MASTER
    interface eth0
    virtual_router_id 51
    priority 101  #priority 101 for master
    advert_int 1
    authentication {
        auth_type PASS
        auth_pass 1111
    }
    virtual_ipaddress {
        192.168.1.6

    }

    track_script {
    chk_haproxy
            }

            }

这是我对 HAproxy 的设置

#---------------------------------------------------------------------
# Example configuration for a possible web application.  See the
# full configuration options online.
#
#   http://haproxy.1wt.eu/download/1.4/doc/configuration.txt
#
#---------------------------------------------------------------------

#---------------------------------------------------------------------
# Global settings
#---------------------------------------------------------------------
global
    # to have these messages end up in /var/log/haproxy.log you will
    # need to:
    #
    # 1) configure syslog to accept network log events.  This is done
    #    by adding the '-r' option to the SYSLOGD_OPTIONS in
    #    /etc/sysconfig/syslog
    #
    # 2) configure local2 events to go to the /var/log/haproxy.log
    #   file. A line like the following can be added to
    #   /etc/sysconfig/syslog
    #
    #    local2.*                       /var/log/haproxy.log
    #
    log         127.0.0.1 local2

    chroot      /var/lib/haproxy
    pidfile     /var/run/haproxy.pid
    maxconn     4000
    user        haproxy
    group       haproxy
    daemon

    # turn on stats unix socket
    stats socket /var/lib/haproxy/stats

#---------------------------------------------------------------------
# common defaults that all the 'listen' and 'backend' sections will
# use if not designated in their block
#---------------------------------------------------------------------
defaults
    mode                    http
    log                     global
    option                  httplog
    option                  dontlognull
    option http-server-close
    option forwardfor       except 127.0.0.0/8
    option                  redispatch
    retries                 3
    timeout http-request    10s
    timeout queue           1m
    timeout connect         10s
    timeout client          1m
    timeout server          1m
    timeout http-keep-alive 10s
    timeout check           10s
    maxconn                 3000

#---------------------------------------------------------------------
# main frontend which proxys to the backends
#---------------------------------------------------------------------
frontend  main *:80
#    acl url_static       path_beg       -i /static /images /javascript /stylesheets
#    acl url_static       path_end       -i .jpg .gif .png .css .js

#    use_backend static          if url_static
#    default_backend             view

#---------------------------------------------------------------------
# static backend for serving up images, stylesheets and such
#---------------------------------------------------------------------
#backend static
#    balance     roundrobin
#    server      static 127.0.0.1:4331 check

#---------------------------------------------------------------------
# round robin balancing between the various backends
#---------------------------------------------------------------------
backend app
mode tcp
    balance     roundrobin
    server  server1 192.168.1.12:80 check inter 2000 rise 2 fall 5
    server  server2 192.168.1.13:80 check inter 2000 rise 2 fall 5

当我启动 HAproxy 时，我遇到了这个错误，我不太确定从哪里开始寻找修复它。也许做过多次这样的人可以帮我解释一下？

503 Service Unavailable No server is available to handle this request. 

但是手动连接到 webserver1 和 webserver2 工作得很好。

我想要的只是位于 HAproxy 后面的网络服务器的简单负载平衡。任何建议或建议都非常感谢。请帮忙？非常感谢。

Answer 1

我从未使用过 HAproxy，但快速搜索使我认为您需要default_backend app立即在下面添加frontend main *:80. 我在该配置中看不到将后端和前端连接在一起的任何地方。

Answer 2

问题出在您的 HAProxy 配置中。当我从你的配置中删除所有评论时，我会得到这个：

global
  log         127.0.0.1 local2

  chroot      /var/lib/haproxy
  pidfile     /var/run/haproxy.pid
  maxconn     4000
  user        haproxy
  group       haproxy
  daemon

  stats socket /var/lib/haproxy/stats

defaults
  mode                    http
  log                     global
  option                  httplog
  option                  dontlognull
  option http-server-close
  option forwardfor       except 127.0.0.0/8
  option                  redispatch
  retries                 3
  timeout http-request    10s
  timeout queue           1m
  timeout connect         10s
  timeout client          1m
  timeout server          1m
  timeout http-keep-alive 10s
  timeout check           10s
  maxconn                 3000

frontend  main *:80

backend app
  mode tcp
  balance roundrobin
  server  server1 192.168.1.12:80 check inter 2000 rise 2 fall 5
  server  server2 192.168.1.13:80 check inter 2000 rise 2 fall 5

现在你可以清楚地看到，根本没有前端的配置。请求通过frontend mainHAProxy到达 HAProxy，但 HAProxy 不知道哪些服务器可以可靠地处理它，因此将返回 503。

您必须使用default_backend或使用 acl将后端链接到前端。

您也应该使用 stats，不仅使用套接字，还使用受保护的 Web 界面。我可以向您展示有关 haproxy 背后的集群的信息，哪些服务器处于离线状态，哪些有问题，有关响应时间等等。对调试非常有用。