README

lbwwd is designed for use with HAProxy

It polls backend server load to dynamically change their weight on haproxy through haproxy socket.


How to start lbwwd:
* all parameters are mandatory
* required system user lbwwd with write privilege on log dir and haproxy socket

/srv/libexec/watchdog/lbwwd -i 60 -b dynamic -s w215:192.168.213.215:80,w216:192.168.213.216:80, -l /srv/log/lbwwd/www_1.log -p /srv/log/lbwwd/www_1.pid -k /srv/sock/haproxy/www_1.sock -u www.mysite.net:/load_check/index.jsp

Parameters:
-i : poll interval
-b : backend name
-s : serverlist; name1:ip1:port1,name2:ip2:port2,name3:ip3:port3,...
-l : log file location
-p : pid file location
-k : haproxy socket location
-u : check url; http_1.1_host_header:/url or /url; must return a string like LOAD=xxx where 0 < xxx < 100

haproxy is configured like this:
global
  daemon
  maxconn 4096
  user haproxy
  group haproxy
  stats socket /srv/sock/haproxy/www_1.sock user lbwwd group haproxy level admin
[...cut...]
backend dynamic
  cookie LBID insert indirect nocache maxidle 30m maxlife 8h
  balance roundrobin
  server w215 192.168.213.215:80 cookie w215 weight 50
  server w216 192.168.213.216:80 cookie w216 weight 50


load check page is like this (jsp)
<%@page import="java.io.*,java.util.*,javax.management.*,org.apache.commons.modeler.Registry"%><%!
public int getLoadValue(String workerName){
  MBeanServer mBeanServer = null;
  mBeanServer = Registry.getRegistry().getServer();
  String qry = "Catalina:type=ThreadPool,name="+workerName;
  Set names = null;
  try {
    names=mBeanServer.queryNames(new ObjectName(qry), null);
    Iterator it=names.iterator();
    if (it.hasNext()) {
      ObjectName oname = (ObjectName)it.next();
      MBeanInfo minfo=mBeanServer.getMBeanInfo(oname);
      MBeanAttributeInfo attrs[]=minfo.getAttributes();
      Object value = null;
      
      String threadsBusyString = mBeanServer.getAttribute(oname, "currentThreadsBusy").toString();
      String threadCountString = mBeanServer.getAttribute(oname, "currentThreadCount").toString();
      
      int threadsBusy = Integer.parseInt(threadsBusyString.trim());
      int threadCount = Integer.parseInt(threadCountString.trim());
	        
      int rap =(int) ((double)threadsBusy * 100 / (double)threadCount) ;
      if (rap > 100) rap=100;
      if (rap < 0) rap = 0;
	  
      return rap;
    }else{
      return 50;
    }
  } catch (Exception e) {
    return 50;
  }
}
%><%
int k = getLoadValue("http-80");
out.println("LOAD="+k);
%>