HTTP::fallback not working

Hi Gary --

 

 

The command "HTTP::fallback" doesn't actually send traffic anywhere, it just sets the fallback target for this connection. The fallback target is only used if there are no responsive, available servers in the target pool. If even 1 server in the target pool looks available (UP [green] or UNCHECKED [blue]) and responds, no fallback is invoked.

 

 

Your iRule, however, is intended to respond with a redirect after several 503 responses. Since the servers have to be UP to respond with a 503 response, calling HTTP::fallback will not have the intended effect.

 

 

A minor change to your code will accomplish the expected redirect after the defined of 503 responses:

when CLIENT_ACCEPTED {
  set retries 0
}
when HTTP_REQUEST {
  set request [HTTP::request]
} 
when HTTP_RESPONSE {
  if {[HTTP::status] eq "503"} {
    if {$retries < [active_members Pool2]} {
      log "503 retrying $retries"
      incr retries
      HTTP::retry $request
    } else {
      log "Max retries exceeded -- redirecting"
      HTTP::redirect "http://livevm1/garys_warning.htm"
    }
  }
}

 

 

You can also apply health monitors to manage pool member availability, or toggle their status manually:

 

 

To make servers "unavailable" when not responding as expected, you will need to apply an HTTP monitor requesting a specific page and expecting a specific response. (Click here for manual page.)

 

 

To manually manage the pool members' status, browse in the GUI to the pool (Local Traffic/Pools), clicking "Members" and use the checkbox & Enable /Disable buttons to change status as required.

 

 

HTH

 

/deb