Forum Discussion
dan_6764
Nimbostratus
NimbostratusCaching with an Irule issue
Hi,
I have a need to cache items that contain a certain uri and nothing else.
E.g I want to cache anything that has "f5" in it and let the rest pass through.
www.mydomain.com/f5/help - cache
www.mydomain.com/surround - don;t cache.
I an using a http-wan-optimized-compression-caching profile with the " http" as its parent. Ramcache is enabled.
My irule is as follows (applied to the relevant VIP, all that happens is that i cache everything. Can anyone help?
thanks
dan
when RULE_INIT {
set ::one_day 86400
}
when HTTP_REQUEST {
if { [HTTP::uri] contains "f5"} {
set cachetime $::one_day
} elseif { [HTTP::host] starts_with "http://" } {
CACHE::disable
}
}
2 Replies
AndrewO_4840The first problem is the line:
} elseif { [HTTP::host] starts_with "http://" } {
HTTP::host will never, ever 'start_with "http://" since HTTP::host is the hostname of the URL - i.e. www.domain.com. It does not include the protocol specifier.
The second problem is that you can't set cache headers on HTTP_REQUEST since that rule is run when the connection comes _in_. Instead you need to apply your rule to the when HTTP_RESPONSE block.
Then comes the issue that you're not actually setting the cache at all. All you're doing is setting a $cachetiem variable in your script, but you're not using it.
What isn't clear is whether you're trying to control the LTM's caching of the object (how long LTM keeps the object in its cache) or whether you're trying to manipulate the client's browser cache. There are different solutions to the two approaches.
The first one requires that you use CACHE:age to find out the age of the object in the LTM's cache, then use CACHE::expire to force the LTM to expire its current cached copy and fetch a fresh object from the server.
The second option requires that you replace the Cache header in the HTTP response, using something like:
HTTP::header replace Expires [clock format [expr ([clock seconds]+$cachetime)] -gmt true -format "%a, %d %b %Y %T %Z"]
dan_6764Hi Thanks for this... think i know what i now need to do.
thanks for your time.
