LB_FAILED not always triggered when all members disabled

Hi there

I'm on a mission to create a generic iRule in order to serve sorry-pages from fallback hosts.

A few criterias that was needed:

1. Strip the subdomain.

2. Preserve the customer URI while rewriting it in the internal request (so that the real page will be served when the user keeps hitting F5).

Potential imporovement:

3. Cache the response

So, I got a good thing going and it looked like it was working as expected. If I go to a random link while there's no available members it serves the page, BUT if I alter the link in the location field of the browser and hit enter it does not serve the fallback page but a 404 instead.

To summarize:

1. Going to http://fallbacktest.test.com/ajsdjasjdjasdjasjd

2. Fallback page is served.

3. Change http://fallbacktest.test.com/ajsdjasjdjasdjasjd to http://fallbacktest.test.com/jkjkjkjkjkjkjkjkjkjkjk

4. A 404 is served.

After some troubleshooting I realized that the reason for this was that the LB_FAILED event was not triggered.

Any ideas of why?

Here's the rule:

when LB_FAILED {

A generic iRule for redirecting users to sorry pages

Create an array separating the host header by .

set hostlist [split [string tolower [HTTP::host]] "."]

Capture the last to items of the array turning ie. subdomain.domain.com to domain.com

set domain "[lindex $hostlist end-1].[lindex $hostlist end]"

Save the length of the host header

set length [llength $hostlist]

set uri [HTTP::uri]

If the length of the hostlist is greater than 1 the value has the correct format.

if { $length > 1 } {

Replace the host header with the string stored in $domain

HTTP::header replace host $domain

Replacing the URI if needed

if { !($uri eq "/default.htm" || $uri starts_with "/img/") } {

HTTP::uri "/index.html"

} else {

log local0. "Correct uri"

}

Reselect pool to the Sorry pool

LB::reselect pool /Site/SorryPages_Pool-80

} else {

HTTP::respond 200 content "Invalid host header format."

}

}

Kind regards,