findstr

Hi Eric,

Here is the wiki page on findstr:

Click here

findstr [ []

* Finds the string within and returns a sub-string based on the and from the matched location. Note the following:

* * The argument may be either a character or length.

* * If the argument is not specified, it defaults to zero.

* * If the argument is not specified, it defaults to the end of the string.

To test this, you can create a test rule that logs the results of the findstr command when the rule is initialized. As the HTTP::uri value won't exist at that point, you can save the URI value you want to test as a string in a variable.

when RULE_INIT {
   set uri "/readingplus/loginSchool.do;jsessionid=F8E2C6F9B4CB4FA10EB277639AD77E96"
   set jsess [findstr $uri "jsessionid" 11 "?"]
   log local0. "\$jsess: $jsess"
}

Here is the output from /var/log/ltm:

Jan 8 17:38:21 tmm tmm[1233]: Rule : $jsess: F8E2C6F9B4CB4FA10EB277639AD77E96

So findstr is searching the URI for "jsessionid", skipping 11 characters (the length of jsessionid plus the '=', and returning everything up to the '?' if there is one. If the terminator of '?' isn't found, the entire string after the skip count is returned.

Using a '?' as the terminator here accounts for the possibility of a query string in the URI.

Holler if you have any questions.

Aaron

Thanks for you help, my problem stems from the following iRule that I am using for persistence. On some of my requests the persistence is not holding and its going to another server in the pool. I am at a loss.

 

 

I am correct to assume that the response is not what is not controlling what server the request gets sent to?

 

 

Any help would be appreciated.

 

- Eri

 

 

 

when HTTP_RESPONSE {

 

if { [HTTP::cookie exists "JID"] } {

 

set resPers [HTTP::cookie "JID"]

 

log "lookup for $resPers in table = >[persist lookup uie $resPers]<"

 

if { [persist lookup uie $resPers] equals "" } {

 

persist add uie $resPers 3700

 

log "NEW PERSIST - added response entry *$resPers* for server [LB::server addr]"

 

} else {

 

log "FOUND PERSIST - continued sessionId *$resPers* for server [LB::server addr]"

 

}

 

}

 

}

 

 

when HTTP_REQUEST {

 

set jsess [findstr [HTTP::uri] "jsessionid" 11 "?"]

 

if { $jsess != "" } {

 

persist uie $jsess 3700

 

 

log "USING PERSIST - used URI value is *$jsess*, server [LB::server addr]"

 

}

 

}

I could never get a 100% solution with only the persist command. Probably my flawed coding, but rather than spin my wheels I switched to the session flavor of persistence so I could store the serverIP. If I get a match, I send the connection directly to the pool member serverIP stored in the session table:

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
    }
  }
}
when HTTP_REQUEST {
  if { [findstr [HTTP::uri] "jsessionid" 11 "!"] != ""} {
    pool MyPool member [session lookup uie [findstr [HTTP::uri] "jsessionid" 11 "!"] ]
  } else {
      pool MyPool
  }
}

I am now using the following and the persistenc edoes not allways hold, its almost as if the table is removing the entry on BIG_IP.

 

 

BTW could the "?" be throwing it off, I want to parse up until there is a ? in the URL. To handle passed in request vars.

 

Why do you use "!" in your parsing of jsessionid?

 

 

 

- Eric

 

 

 

when HTTP_RESPONSE {

 

if { [HTTP::cookie exists "JID"] } {

 

set resPers [HTTP::cookie "JID"]

 

if { [persist lookup uie $resPers] equals "" } {

 

session add uie $resPers [IP::server_addr] 3700

 

}

 

}

 

}

 

 

 

when HTTP_REQUEST {

 

set jsess [findstr [HTTP::uri] "jsessionid" 11 "?"]

 

if { $jsess != "" } {

 

pool test_pool member [session lookup uie [findstr [HTTP::uri] "jsessionid" 11 "?"] ]

 

} else {

 

pool test_pool

 

}

 

}

I trim at the ! so I only get the session ID. If you trim at the ? you also get the unique weblogic server identifiers, which I have noticed occasionally change.

If you want to discover these unique identifiers real time, you can insert the header X-Weblogic-Request-ClusterInfo towards the application:

when CLIENT_ACCEPTED {
  set get_server_mappings 1
}
when HTTP_REQUEST {
  if { $get_server_mappings } {
    HTTP::header insert "X-Weblogic-Request-ClusterInfo" "true"
    set get_server_mappings 0
  }
}

Then on the next response, extract the information from the header X-WebLogic-Cluster-List

when HTTP_RESPONSE {
  if { [HTTP::header exists "X-WebLogic-Cluster-List"] }{
    set server_mappings [split [HTTP::header "X-WebLogic-Cluster-List"] "|" ]
     Remove header before returning to client
    HTTP::header remove "X-WebLogic-Cluster-List"
  }
}

I'll leave it to you to discover what to do with this information, weblogic returns a lot of useful information!

Thanks for the reply.

 

I am not using any Enterprise Application Server .... yet.

 

Just multiple Tomcats.

 

 

Thanks.

 

 

 

Eric