Instructing BigIP to expire RAM Cache when it receives a URL Query

Caleb

I've done some testing here, and think I've got a working iRule...

Apologies, i've striped out some of your logic, however it should be easy enough to put back in...

Anyways, here's a copy of my iRule...

 when RULE_INIT {

 Debug variable
set static::ExpireRAMCacheDebug 1

}

when HTTP_REQUEST {

if { $static::ExpireRAMCacheDebug } { log local0. "Processing HTTP_REQUEST at Priority 500." }

 Set default cache trigger value. 
set expire_cache_trigger 0

 Check if from authorized IP address. 
if { [class match [IP::client_addr] equals Authorized_IPs] } {

 Check HTTP::query for the expire param.
if { [string tolower [HTTP::query]] contains "expire" } {
 Param present in HTTP::query
if { $static::ExpireRAMCacheDebug } { log "Request to expire [HTTP::uri] received." }

 Set the expire trigger.
set expire_cache_trigger 1

 Save a copy of the URI with the param and value removed
set uri [string map [list "expire" ""] [HTTP::uri]]

 Replace && with & in the updated query string if && is present and set the URI to this
set uri [string map "&& &" $uri]

 Check if there are no other query items
if { $uri contains "&" } {
 Another query param exists
set uri [string map [list "?&" "?"] $uri]
 Log the cached and updated values for the URI
log local0. "Other Query params present. Original URI: [HTTP::uri], updated URI: $uri"
HTTP::uri $uri

} else {
set uri [string map [list "?" ""] $uri]
 Log the cached and updated values for the URI
log local0. "No Query params present. Original URI: [HTTP::uri], updated URI: $uri"
HTTP::uri $uri
}
}
}
}

when CACHE_REQUEST {

if { $static::ExpireRAMCacheDebug } { log local0. "Processing CACHE_REQUEST at Priority 500." }

 Check for expire_cache_trigger
if { $expire_cache_trigger } {

 Expire the CACHE entry.
if { $static::ExpireRAMCacheDebug } { log local0. "Expiring CACHE item $uri." }
CACHE::expire

 Record the item expiry. 
log "Cache Item $host$uri Expired"

 Tidy up
unset expire_cache_trigger
}
} 

It seems to work for me on some quick testing... Will give it a better run-down tomorrow...

Comments/Improvements welcome...

Cheers

Gavin