Selecting the pool member to which I want to persist

We have a need to be able to quickly confirm that a pool member has become partially disabled. Ideally, a monitor would serve this purpose, but it would be required to navigate through a number of layers including authentication in order to reach the

 

necessary level of testing within the web application. Does anyone have an example of a more sophisticated monitor used for this type of health check?

 

 

That question aside, it would still be useful for us to be able to persist to a particular pool member for testing purposes. One solution I've explored is to set up a virtual with no default pool but with a one connect profile. I created a number of single-server pools, one for each node used in our production pools. I then append ?testpool=server1-pool to any working URL, and employ a "pool cue" iRule which looks like:

 

 

when HTTP_REQUEST {

 

if { [string match "*testpool=*" [ HTTP::uri] ] } {

 

Split the URI on its question mark (?) into

 

mainparts list.

 

set mainparts [split [ HTTP::uri ] ?]

 

Set the newurl to the first of the mainparts of the

 

URI (everything before the question mark).

 

set newurl [lindex $mainparts {0}]

 

set new_qs ""

 

Initialize the delimiter to a question mark (?).

 

set delimiter "?"

 

Split the second element of mainparts list on

 

ampersand (&) into a list of parameters, then split

 

each parameter on the equals (=) sign.

 

foreach thisparam [split [ lindex $mainparts {1} ] & ] {

 

foreach {name value} [ split $thisparam = ] {

 

If the parameter name is "testpool",

 

then set the requested_pool var.

 

if { [string match "testpool" $name] } {

 

set requested_pool $value

 

Otherwise, append the parameter to the newurl.

 

} else {

 

set newurl "$newurl$delimiter$name=$value"

 

set new_qs "$new_qs$delimiter$name=$value"

 

Now that delimiter has been used once,

 

set it to an ampersand (&) for subsequent vars.

 

if { [string match "?" $delimiter]} {

 

set delimiter "&"

 

}

 

}

 

}

 

}

 

HTTP::uri $newurl

 

log local0. "pool requested: $requested_pool"

 

pool $requested_pool

 

}

 

}

 

 

The rule is not yet trapping for nonexistent pools, and errors in those instances, but seems to work for single-page tests of existing pools. Setting a one connect profile for this virtual allows me to revisit the URL without the testpool=server1-pool parameter, and it will still persist without using the irule. However, I've noticed that if I reload the page too fast, the LTM seems to lose the connection or open a new one, such that the browser's connection is reset. Am I on the right track here, or is this a dead-end? Have I made this overly-complicated?

 

 

I've seen a number of posting here wherein folks are trying to maintain a member persistence on subsequent requests, but can anyone advise me on how to initially persist to a particular member?

 

 

Thanks,

 

 

dave