| Russ Allbery > Software > lbcd | lbcd Manual Page > |
(responder for load balancing)
Maintained by Russ Allbery <rra@stanford.edu>
Copyright 1993, 1994, 1996, 1997, 1998, 2000, 2003, 2004 Board of Trustees, Leland Stanford Jr. University. This software is distributed under an MIT-style license. Please see the section LICENSE below for terms of use and redistribution.
The lbcd daemon runs on a Unix system and answers UDP queries (by default on port 4330) with information about system load, number of logged on users, uptime, and free /tmp space. The intention is for this information to be used by a load balancer service to choose the best system to direct incoming connections to. It was designed for use with the lbnamed DNS load balancer, available at:
It was originally written by Roland Schemers, was rewritten by Larry Schwimmer to add protocol version 3 with some additional features and service probing, and is currently maintained by Russ Allbery.
The information provided isn't particularly sophisticated, and a good hardware load balancer will be able to consider such things as connection latency and responsiveness to make better decisions, but lbcd with lbnamed works quite well for smaller scale problems, scales well to multiple load balance pools for different services, and is much simpler and cheaper to understand and deploy.
Included in this package is a small client program, lbcdclient, which can query an lbcd server and display a formatted version of the returned information.
Compilation and installation are very simple. Just run:
./configure
make
and then as root, run:
make install
This will install lbcd in /usr/local/sbin, lbcdclient in /usr/local/bin, and the man pages in /usr/local/man. To specify a different location for installation, pass the --prefix option to configure. For more information, run:
./configure --help
lbcdclient is written in Perl, so you may have to edit the first line of the script to point to the correct Perl location on your system. It does not use any sophisticated Perl features or add-on modules.
You will generally want to start lbcd at system boot. There is an init script in debian/init for Debian systems; for other systems, all that is needed is a simple init script to start lbcd with the appropriate options or kill it again. It writes its PID into /var/run/lbcd.pid by default (and this can be changed with the -P option). On many systems, lbcd will need to run as root or as a member of particular groups to obtain system load average and uptime information.
Copyright 1993, 1994, 1996, 1997, 1998, 2000, 2003, 2004 Board of Trustees, Leland Stanford Jr. University.
Permission is hereby granted, free of charge, to any person obtaining a copy of this software and associated documentation files (the "Software"), to deal in the Software without restriction, including without limitation the rights to use, copy, modify, merge, publish, distribute, sublicense, and/or sell copies of the Software, and to permit persons to whom the Software is furnished to do so, subject to the following conditions:
The above copyright notice and this permission notice shall be included in all copies or substantial portions of the Software.
THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
| Russ Allbery > Software > lbcd | lbcd Manual Page > |