A10 AX device url hash Aflex脚本（tcl basic）

第一次用TCL，也是第一次测试A10的LB设备。
根据公司原来架构要求，改写了原来的images LB系统的url hash，提高了容错能力。
主要构想是要实现url hash的一致性，连续性的负载均衡要求；

算法很简单，url md5 hash后根据nodes数量为取模值然后转到后端的node id；
如果该后端出现故障，将nodes数量减去当前的故障设备，重新取模后转到后端。

A10脚本不是完整的TCL语法，除了增加了自己的设备command外也相应了删减了很多TCL的command。
比如proc就不能用了，导致我的语法显的啰嗦了。
设备上的脚本为AfleX，转帖如下：

#后端设备列表 when RULE_INIT {   set ::ips [list "xx.xx.xx.1" "xx.xx.xx.2" "xx.xx.xx.3" "xx.xx.xx.4" "xx.xx.xx.5" ] }  when HTTP_REQUEST {   #取url做md5并转成整数型   set url_hash [HTTP::host][HTTP::uri]   set md5_hash [md5 $url_hash]   set int_md5 [scan $md5_hash %c]   set nodes [llength $::ips]   #debug 信息排错用   log local0.NOTICE "Each variable:All node: $nodes; URI hash: $int_md5"   #在循环判断service-groups和nood状态并指向后端   while 1 {     if { [LB::status pool imgcache_pool] == "down" } {       break       log local0.ERR "Imgcache group is down or disables."     }     #取模     set hashs [expr $int_md5 % $nodes]     #模数指向后端     switch $hashs {       0 {         set IP [lindex $::ips 0]         if { [LB::status node $IP port 80 tcp] == "up" } {           node $IP 80           break         } else {           set nodes [expr $nodes - 1 ]           log local0.ERR "IP addr:$IP is down. no hash its service."         }       }       1 {         set IP [lindex $::ips 1]         if { [LB::status node $IP port 80 tcp] == "up" } {           node $IP 80           break         } else {           set nodes [expr $nodes - 1 ]           log local0.ERR "IP addr:$IP is down. no hash its service."         }       }       2 {         set IP [lindex $::ips 2]         if { [LB::status node $IP port 80 tcp] == "up" } {           node $IP 80           break         } else {           set nodes [expr $nodes - 1 ]           log local0.ERR "IP addr:$IP is down. no hash its service."         }       }       3 {         set IP [lindex $::ips 3]         if { [LB::status node $IP port 80 tcp] == "up" } {           node $IP 80           break         } else {           set nodes [expr $nodes - 1 ]           log local0.ERR "IP addr:$IP is down. no hash its service."         }       }       4 {         set IP [lindex $::ips 4]         if { [LB::status node $IP port 80 tcp] == "up" } {           node $IP 80           break         } else {           set nodes [expr $nodes - 1 ]           log local0.ERR "IP addr:$IP is down. no hash its service."         }       }     }   }     #http_header中插入真实client ip     if { not [HTTP::header exists "CLIENT_IP"] } {     HTTP::header "CLIENT_IP" [IP::client_addr]   } }