Re: Writing hooks for Perlbal

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.