Need help with iRule error log message

Hi Sahir,

you may try to add an additional debug lines to your iRule to get additional informations. It would help to see whats going on behind the scenes...

Change...

pool ets_80-pool member [session lookup uie [findstr [HTTP::uri] "jsessionid" 11 "!"] ]

... to ...

if { [catch { 

    pool ets_80-pool member [session lookup uie [findstr [HTTP::uri] "jsessionid" 11 "!"]]

}]} then {

    log -noname local0.debug "Extended Error Info: \"[subst \$::errorInfo]\""
    log -noname local0.debug "URI Info: \"[HTTP::uri]\""
    log -noname local0.debug "UIE Info: \"[session lookup uie [findstr [HTTP::uri] "jsessionid" 11 "!"]]\""
    log -noname local0.debug "Pool Info: \"[members -list ets_80-pool]\""

    drop ; We will still terminate the connection since it has thrown an error!

}

Note: The change creates an extended error handle. I didn't test the provided code yet, but it should work as before with the difference, that it will log additional information when the error happens again.

Warning: Please take a look to your LTM log while saving your iRule. If any CMP related warning will raise, then revert the change and come back again. The code is accessing/hacking $::errorInfo to get some additional information... 😉

Cheers, Kai

HI Sahir,

I believe I've catched the glitch in your iRule, it seems to be an logic error that would create some havoc when flushing the persistent table (this would happen during migration).

Please repost the entire iRule to get sure. And apply propper formating and syntax highlighting...

Cheers, Kai

Ok, I have deleted that one and adding the following, let me know if that is what you are looking for?

when HTTP_RESPONSE {
    if { [HTTP::cookie exists "JSESSIONID"] } {
      set trimID [lindex [split  [HTTP::cookie "JSESSIONID"] "!" ] 0 ]
      if { [session lookup uie $trimID] equals "" } {
        session add uie $trimID [IP::server_addr] 1800
        log local0. "added server entry [session lookup uie $trimID] for jsessionID $trimID "
      } else {
        log local0. "existing server entry [session lookup uie $trimID] for jsessionID $trimID"
      }
    }
  }
  when HTTP_REQUEST {
    if { [active_members et-pool] == 0 } {
      HTTP::redirect "http://[HTTP::header "X-Forwarded-Host"]/unavailable/etServices.html"
    } else {
    if { [HTTP::header exists "X-Forwarded-Host"] } {
      HTTP::header replace "Host" [HTTP::header "X-Forwarded-Host"]
    }
    if { [HTTP::cookie exists "em-et"] } {
        log local0. "Persisting by cookie em-et, contents are [HTTP::cookie "em-et"]"
    } else {
      if { [findstr [HTTP::uri] "jsessionid" 11 "!"] != ""} {
        pool ets_80-pool member [session lookup uie [findstr [HTTP::uri] "jsessionid" 11 "!"] ]
        log local0. "jsessionID [findstr [HTTP::uri] "jsessionid" 11 "!"] sent to [session lookup uie [findstr [HTTP::uri] "jsessionid" 11 "!"] ]"
      } else {
        pool ets_80-pool
        log local0. "No jsession ID, local balancing the connection..."
      }
    }
    }
  }

Hi Sahir,

the problem can be found in this code block...

            if { [findstr [HTTP::uri] "jsessionid" 11 "!"] != ""} {
                pool ets_80-pool member [session lookup uie [findstr [HTTP::uri] "jsessionid" 11 "!"] ]
               log local0. "jsessionID [findstr [HTTP::uri] "jsessionid" 11 "!"] sent to [session lookup uie [findstr [HTTP::uri] "jsessionid" 11 "!"] ]"
            } else {
                pool ets_80-pool
               log local0. "No jsession ID, local balancing the connection..."
            }

If the client sends an [HTTP::uri] containing the string jsessionid, you'll will use a substring of it to find an matching [session lookup uie] record. But then you don't verify if the session query has deliverd any values before proceeding with the member node selection. I highly doubt this code has ever worked stable...?

An improved code would look like this...

when HTTP_RESPONSE {
    if { [HTTP::cookie exists "JSESSIONID"] } {
        set trimID [lindex [split  [HTTP::cookie "JSESSIONID"] "!" ] 0 ]
        if { [session lookup uie $trimID] equals "" } {
            session add uie $trimID [IP::server_addr] 1800
           log local0. "added server entry [session lookup uie $trimID] for jsessionID $trimID "
        } else {
           log local0. "existing server entry [session lookup uie $trimID] for jsessionID $trimID"
        }
    }
}

when HTTP_REQUEST {
    if { [active_members et-pool] == 0 } {
        HTTP::redirect "http://[HTTP::header "X-Forwarded-Host"]/unavailable/etServices.html"
    } else {
        if { [HTTP::header exists "X-Forwarded-Host"] } {
            HTTP::header replace "Host" [HTTP::header "X-Forwarded-Host"]
        }
        if { [HTTP::cookie exists "em-et"] } {
           log local0. "Persisting by cookie em-et, contents are [HTTP::cookie "em-et"]"
        } else {
            set pool_member [session lookup uie [findstr [HTTP::uri] "jsessionid" 11 "!"]]
            if { $pool_member ne "" } {
                pool ets_80-pool member $pool_member
               log local0. "jsessionID [findstr [HTTP::uri] "jsessionid" 11 "!"] sent to [session lookup uie [findstr [HTTP::uri] "jsessionid" 11 "!"] ]"
            } else {
                pool ets_80-pool
               log local0. "No jsession ID, local balancing the connection..."
            }
        }
    }
}

Note: You may apply the improved code before updating the device...

Cheers, Kai

Kai,

first, Thanks for your effort trying to help on this & you could be right about the rule not being stable. second, as I mentioned before I am an iRules newbie, and have no idea what is this iRule is doing, I was given this project and I am still learning, I am a Cisco guy in first place.

third, I am wondering if you missed an else statement in your suggested code in the following part:

 when HTTP_REQUEST {
    if { [active_members et-pool] == 0 } {
        HTTP::redirect "http://[HTTP::header "X-Forwarded-Host"]/unavailable/etServices.html"
    } else {
        if { [HTTP::header exists "X-Forwarded-Host"] } {
            HTTP::header replace "Host" [HTTP::header "X-Forwarded-Host"]
        }
        if { [HTTP::cookie exists "em-et"] } {
           log local0. "Persisting by cookie em-et, contents are [HTTP::cookie "em-et"]"
        } else {
            set pool_member [session lookup uie [findstr [HTTP::uri] "jsessionid" 11 "!"]]
            if { $pool_member ne "" } {
                pool ets_80-pool member $pool_member
               log local0. "jsessionID [findstr [HTTP::uri] "jsessionid" 11 "!"] sent to [session lookup uie [findstr [HTTP::uri] "jsessionid" 11 "!"] ]"
            } else {
                pool ets_80-pool
               log local0. "No jsession ID, local balancing the connection..."
            }
        }
    }
}

and is it should be?

when HTTP_REQUEST {
    if { [active_members et-pool] == 0 } {
        HTTP::redirect "http://[HTTP::header "X-Forwarded-Host"]/unavailable/etServices.html"
    } else {
        if { [HTTP::header exists "X-Forwarded-Host"] } {
            HTTP::header replace "Host" [HTTP::header "X-Forwarded-Host"]
        } else{
        if { [HTTP::cookie exists "em-et"] } {
           log local0. "Persisting by cookie em-et, contents are [HTTP::cookie "em-et"]"
        } else {
            set pool_member [session lookup uie [findstr [HTTP::uri] "jsessionid" 11 "!"]]
            if { $pool_member ne "" } {
                pool ets_80-pool member $pool_member
               log local0. "jsessionID [findstr [HTTP::uri] "jsessionid" 11 "!"] sent to [session lookup uie [findstr [HTTP::uri] "jsessionid" 11 "!"] ]"
            } else {
                pool ets_80-pool
               log local0. "No jsession ID, local balancing the connection..."
            }
        }
    }
}

Thanks.