Elliot,
Well, I think I'm onto something. I've been hacking on Service.pm and the code that spawns new servers. Around line 1162 I've added a subroutine which verifies that the server is available on the specified ip and port it receives from $self->{pool}->get_backend_endpoint. If the server isn't there, then I execute a lot of code and return a new $ip and $port, and then let the subroutine continue.
I'm a little concerned that this gets executed only when new backends are created, and that if an existing backend with a persistent connection goes down this code won't be executed. I'd like to find a better place for it and write a 'hook' for it. Essentially a 'verify' server hook. Any ideas or suggestions would be appreciated.
-=Raistlin
On 8-Oct-06, at 12:11 PM, Elliot F wrote: I would suggest taking a look at the code around the backend_client_assigned hook. If you haven't already, take a look at the doc/hacking/hooks.txt file.
I'm not sure, but your problem may quickly get much more complex. I would not be surprised if you have to make your own hook somewhere, or modify perlbal.
If the 'backend_client_assigned' hook isn't enough, I'm assuming you would want to look at './lib/Perlbal/BackendHTTP.pm', and specifically the 'assign_client' sub around line 159. I'm not saying this is the answer, but it would be where I would start looking.
Hope that helps,
Elliot
Raistlin Majere wrote: Alright, I have the plugin/callback being called. Looks like I just needed to add "plugins = MyPlugin" (where MyPlugin is the package in the Perlbal/Plugin directory). The callback functionality looks useful for polling things and reacting accordingly, I've implemented this, however I am curious how to rewrite a request to a different backend server. Ideally I'd like to be able to be able to: Accept a request to a virtualhost Verify that the backend server is up and running if it's not then hold the request while I either: a) bring the backend server up b) rewrite the request to a different server Any ideas how to redirect the request, POST data, etc to a different machine? Raistlin,
Take a look at registering a callback that perlbal will trigger every N seconds. AtomStream.pm has it being used. It's called 'Perlbal::Socket::register_callback'. You would be able to do whatever check(s) you want, and react accordingly (mark it as down somehow, reconfigure perlbal, etc.) And it wouldn't be doing it for every request.
Just make sure you don't block. :)
Elliot
Raistlin Majere wrote: I've installed and configured perlbal and have run into some difficulties. I've setup perlbal to be a reverse proxy so that it correctly proxies virtualhosts to the appropriate servers. (i.e. vhost1.example.com, vhost2.example.com correctly reverse proxies for vhost1.com and vhost2.com respectively) This is working perfectly, and wasn't too difficult to configure. However now I want to write some code that will: First verify that the backend server is alive Second that the backend server can answer requests on the port I'm trying to talk to And if it's NOT alive and able to respond to requests that I can redirect requests to a different server, or execute some code to bring the downed server up, before retrying. I've tried to use the Perlbal::ClientProxy "start_proxy_request" hook, however that seems to affect each and every request (i.e. each html page, graphic, etc.) I need to be able to check to see if the backend server is alive, and if it's not, tell Perlbal: "Whoa hold your horeses" long enough for me to bring a server up (I can do this with some scripts I have), and then redirect the request to the new server. Any help or advice would be greatly appreciated.
|
