BlurredVision_1
Nimbostratus
NimbostratusHTTP Double Dipping...
All,
I know this is a crazy corner case, and that there are probably 100 ways to do this with the app, the application guys are looking for some f5 lovin to get this working as a short term workaround (I have been talking up iRules for so long, I think they decided to make me put my money where my mouth is!!)
I have an application owner who needs to run extended QA n the new version of a server while maintaining the old version as the production system for a while. Long story short, it is a web services environment that they need to run 2 versions of the application side by side on the same data stream. The aim is to have the same WS transactions run against V1 and V2 one after the other, but for V1 to be the one that is actually carried back to the requesting server. (ie: to start with V1 is authorative, V2 is run, but the responses are ignored)
So far the config has a VS with a 2 pools of 1 server (v1 and v2).
Using an iRule, we have managed to get the following workflow:
iRule INIT
set loop 0
set lb_run 0
when HTTP_REQUEST
UNCHUNK
stuff HTTP::request into a var
if loop == 0
select pool V2
if loop == 1
select pool V1
when HTTP_RESPONSE
if loop == 0
incr loop
HTTP::retry $var
when LB_SELECTED
if loop == 0
if lb_run == 0
LB::reselect pool v2
set lb_run 1
else
LB::reselect pool v1
I know there is some weirdness in the logic of the flow, but I am still not 100% sure how the rule events hang topgether.
output of this rule runs correctly the first time, but as the key vars are established in irule init, it gets stuck in the second iteration as the deafult state.
I tried to reset the loop and lb_run counters in various places, but it ends up looping.
Where should I be looking to reset the state of the loops to get it to run properly again.
Full iRule as follows:
when RULE_INIT {
outputs useful information to logs when debug is set to 1
set ::debug 1
set ::first_lb_selected 0
set ::iteration 0
}
when HTTP_REQUEST {
unchunk
HTTP::version "1.0"
if { $::iteration == 0} {
set creq [HTTP::request]
if { $::debug } { log local0. "HTTP_REQ at ::iteration 0" }
pool Pool-V2
}
if { $::iteration == 1} {
if { $::debug } { log local0. "HTTP_REQ at ::iteration 1" }
pool Pool-V1
}
}
when HTTP_RESPONSE {
if { $::debug } { log local0. "HTTP_RES triggered" }
if { $::iteration == 0 } {
if { $::debug } { log local0. "HTTP_RES at ::iteration 0" }
if { $::debug } { log local0. "HTTP_RES lb detach:" }
LB::detach
if { $::debug } { log local0. "HTTP_RES set ::iteration to 1" }
set ::iteration 1
if { $::debug } { log local0. "HTTP_RES retrying" }
HTTP::retry $creq
}
if { $::debug } { log local0. "This is the last line!" }
if { $::first_lb_selected == 1 && $::iteration == 1 }{
set ::first_lb_selected 0
set ::iteration 0
}
}
when LB_SELECTED {
if { $::debug } { log local0. "LB::server is [LB::server addr]" }
if { $::iteration == 0 } {
if { $::first_lb_selected == 0} {
if { $::debug } { log local0. "LB_Selected at ::iteration 0 setting GP10" }
LB::reselect pool V2
set ::first_lb_selected 1
}
} else {
if { $::debug } { log local0. "LB_Selected at ::iteration 0 setting GP7" }
LB::reselect pool V1
}
}
