Re: lame load balancer, mod_proxy, and sticky sessions
The idea to modify mod_proxy.c is probaly the most convenient solution. Instead of configure backend machine from the ProxyPass setting, you may specifically assign it to the one in the cookie, which takes only a few lines of code to change --- well, plus extra steps to handle the cookie. ProxyPass is processed at the URL translation phase. If the same cookie is used for other purposes such as access control then there is no cost at all. (sorry, this is in the c API, kind of OT.) Peter Bi Hello, I'd like to know if it is possible to use mod_proxy as a sticky session manager. Basically, I'd like to put mod_proxy behind the load balancer and allow the proxy servers to talk to the mod_perl servers. Unfortunately, the load balancer does not allow for sticky sessions and only bounces the user round-robin style. I am playing with the idea of sending a cookie down to the client and using it to stick a user to a particular mod_perl server, but I'd like mod_proxy to figure it out which server and send the user to the defined machine. I'd also like to enable a checking mechanism to determine if a mod_perl server is up before the user is sent to the location specified in the cookie. If the machine that the client is stuck to is down, I'd like to reroute. I know high powered load balancers do this already, but I'd like to explore dedicating a few medium sized servers to do as there is surplus of these and f5's cost $$$. I apologize in advance if this is a bit off topic! Thanks, Al ** This email and any files transmitted with it are confidential and intended solely for the use of the individual or entity to whom they are addressed. If you have received this email in error please notify the system manager. This footnote also confirms that this email message has been swept by MIMEsweeper for the presence of computer viruses. www.mimesweeper.com **
Re: lame load balancer, mod_proxy, and sticky sessions
[EMAIL PROTECTED] wrote: The idea to modify mod_proxy.c is probaly the most convenient solution. Instead of configure backend machine from the ProxyPass setting, you may specifically assign it to the one in the cookie, which takes only a few lines of code to change --- well, plus extra steps to handle the cookie. But you're not accounting for the possibility of server failure on the backend. A proper load-balancer (including the open source ones and mod_backhand) would detect dead servers and handle the failover to another server. Building this yourself is probably not worth it, with so many open source solutions already available. - Perrin
Re: lame load balancer, mod_proxy, and sticky sessions
[EMAIL PROTECTED] wrote: But you're not accounting for the possibility of server failure on the backend. A proper load-balancer (including the open source ones and mod_backhand) would detect dead servers and handle the failover to another server. This is true. Then one has to ping the network which is very expensive. --- yes, a special product would be better. Building this yourself is probably not worth it, with so many open source solutions already available. The original post consists of two parts: to proxy to the right machine and to handle the failover. If there is a quick solution to the first part, why not make it and have the second part be solved later ? Peter Bi [EMAIL PROTECTED] wrote: The idea to modify mod_proxy.c is probaly the most convenient solution. Instead of configure backend machine from the ProxyPass setting, you may specifically assign it to the one in the cookie, which takes only a few lines of code to change --- well, plus extra steps to handle the cookie. But you're not accounting for the possibility of server failure on the backend. A proper load-balancer (including the open source ones and mod_backhand) would detect dead servers and handle the failover to another server. Building this yourself is probably not worth it, with so many open source solutions already available. - Perrin
Re: lame load balancer, mod_proxy, and sticky sessions
On Fri, Sep 06, 2002 at 08:44:39AM -0400, Calbazana, Al wrote: Hello, I'd like to know if it is possible to use mod_proxy as a sticky session manager. Basically, I'd like to put mod_proxy behind the load balancer and allow the proxy servers to talk to the mod_perl servers. Unfortunately, the load balancer does not allow for sticky sessions and only bounces the user round-robin style. I am playing with the idea of sending a cookie down to the client and using it to stick a user to a particular mod_perl server, but I'd like mod_proxy to figure it out which server and send the user to the defined machine. I'd also like to enable a checking mechanism to determine if a mod_perl server is up before the user is sent to the location specified in the cookie. If the machine that the client is stuck to is down, I'd like to reroute. I know high powered load balancers do this already, but I'd like to explore dedicating a few medium sized servers to do as there is surplus of these and f5's cost $$$. I apologize in advance if this is a bit off topic! Two things come to mind. First mod_rewrite has plenty of features that will let you do primitive load balancing. See http://httpd.apache.org/docs/misc/rewriteguide.html Look at the examples that show how to combine a cookie with the URI and you can use regexes to control which host is chosen. Also check out mod_backhand (discussed on this list, check the archives) http://www.backhand.org/ -- Paul Lindner[EMAIL PROTECTED] | | | | | | | | | | mod_perl Developer's Cookbook http://www.modperlcookbook.org/ Human Rights Declaration http://www.unhchr.ch/udhr/
Re: lame load balancer, mod_proxy, and sticky sessions
Calbazana, Al wrote: I'd like to know if it is possible to use mod_proxy as a sticky session manager. It's possible in the sense that you could write a sticky session manager and glom it onto mod_proxy. It's certainly not there right now. If you just want a free load-balancer, take a look at one of the many open source projects out there like http://linux-ha.org/. - Perrin
Re: lame load balancer, mod_proxy, and sticky sessions
Ask Bjoern Hansen wrote: On Fri, 6 Sep 2002, Perrin Harkins wrote: Calbazana, Al wrote: I'd like to know if it is possible to use mod_proxy as a sticky session manager. It's possible in the sense that you could write a sticky session manager and glom it onto mod_proxy. It's certainly not there right now. Uh, couldn't a combination of mod_backhand and mod_rewrite (using cookies) do it? I believe mod_backhand could do it alone, but that's not mod_proxy. None of the approaches I've seen for using mod_rewite with mod_proxy for load-balancing handle the high-availability part, i.e. removing servers that have gone down from rotation, but mod_backahand does, and it handles sticky sessions. - Perrin
