Hi,
On 6/27/06, Ruediger Pluem <[EMAIL PROTECTED]> wrote:
Brian Rectanus wrote:
> On 6/26/06, Mladen Turk <[EMAIL PROTECTED]> wrote:
>>
>> Thinking of it more deeply, the only valuable env var would
>> be BALANCER_SESSION_ROUTE.
>> All other parms are meaningless for the client unless
>> you wish to create a loadbalancer as a cgi script.
>>
>> Regards,
>> Mladen.
>>
>>
>
> I had two intentions with BALANCER_SESSION_ROUTE:
>
> 1) Provide a way for client to detect a server switch and possibly
> cleanup (maybe remove the session cookie so next attempt would not
> fail if server was gone and nofailover=On). Cleanup will be important
> since these are session cookies and the server app has no way to
> cleanup (it is down) and the user must restart his/her browser (remove
> session cookie) to rebalance.
>
> RewriteRule "%{ENV:BALANCER_SESSION_ROUTE}
> !="%{BALANCER_WORKER_ROUTE}" [E=REBALANCED:1]
> Header add Set-Cookie "MYCOOKIE=;
> path=/; expires=Monday, 01-Jan-1990 08:00:00 GMT
>
> " env=REBALANCED
Doh, yes. That is what I get for posting examples I have not tested ;)
As far as I can see this also does not work, because these environment
variables are set during the handler phase and thus are not available
for rewrite rules.
But I guess the patch can be used to setup the appropriate session
routing inside of httpd if your backend does not support adding a route
to the session cookie (this has been requested frequently):
SetEnvIf ^Cookie$ MYCOOKIE HAVE_ROUTE
Header add Set-Cookie "MYCOOKIE=SOMEVALUE.%{BALANCER_WORKER_ROUTE}e;
path=/;" env=!HAVE_ROUTE
ProxyPass /test balancer://mycluster/test stickysession=MYCOOKIE
nofailover=On
Of course this approach does not notice the client once you have
switched your backend worker. Using
Header add Set-Cookie "MYCOOKIE=SOMEVALUE.%{BALANCER_WORKER_ROUTE}e;
path=/;"
ProxyPass /test balancer://mycluster/test stickysession=MYCOOKIE
nofailover=On
fixes this, but sets the cookie on every response which may not be what
you want.
Yeah, I end up setting on every request. Some further patching I
would like to do is add the ability for mod_proxy_balancer to actually
add/remove the cookie if you use something like
store-route=cookie:MYCOOKIE or similar.
I'll take a closer look and see if I can get the other env vars to be
a bit more useful. I ended up adding them in more for completion than
for my needs and as you have seen they are not that useful/practical.
Thanks,
-B
