FQDN Node with Route Domains

Emad · ‎18-May-2016

How can we add route domain in FQDN based nodes. In Address based node it can be added with %1 but how this will be done in FQDN based nodes.

awilhelm · ‎18-May-2016

Currently this is not supported with FQDN nodes, though it might happen if FQDN nodes are created in an administrative partition with a nonzero route domain (I have not tested this).

There is an RFE open for this, tracked as

ID522465

. This will be implemented in a future release. If you'd like to indicate interest, which helps us prioritize RFEs, please open an SR with F5 Support referencing this ID and asking to be linked to it.

Con_Spathas_246 · ‎02-Jul-2016

Here's my attempt at it...


 Rule Name:        MY_RD_FQDN_IRULE
 Rule Date:        01/07/2016
 Rule Version:     1.0

 Rule Description: This iRule is designed to lookup an IP for an FQDN and then use the IP for the serverside connection.
                   Simply edit the RULE_INIT variables to modify for your needs.  
                   Test before using in any environment. This rule is provided *as-is* without warranty or liability. 
   
 Rule History:     1.0 - 01/07/2016 - C.Spathas (Ardenta) - Initial Version inspired by DevCentral
                   https://devcentral.f5.com/questions/dynamic-pool-members-with-dns-resolution

when RULE_INIT {

     Set some static variables and lists
    set static::MY_RD_FQDN_GBLVAR "www.google.com"
    set static::MY_RD_FQDN_ROUTE_DOMAIN_GBLVAR "%1"
    set static::MY_RD_FQDN_DNS_SRV_GBLST {8.8.8.8 8.8.4.4}

     Set debug logging on/off (0 for none, 1 for drop/deny/error and 2 for all logging)
    set static::MY_RD_FQDN_DEBUG_GBLVAR 2

}

when CLIENT_ACCEPTED {

     Select a DNS server from the list and sppend the Route Domain
    set DNS_SERVER_LCLVAR "[lindex $static::MY_RD_FQDN_DNS_SRV_GBLST [expr {int(rand()*[llength $static::MY_RD_FQDN_DNS_SRV_GBLST])}]]$static::MY_RD_FQDN_ROUTE_DOMAIN_GBLVAR"

     Debug Logging
    if {$static::MY_RD_FQDN_DEBUG_GBLVAR==2}{log local0. "DNS Server selected was $DNS_SERVER_LCLVAR"}

     Perform the Lookup and append the Route Domain
    set FQDN_IP_LCLVAR "[lindex [RESOLV::lookup @$DNS_SERVER_LCLVAR -a $static::MY_RD_FQDN_GBLVAR] 0]$static::MY_RD_FQDN_ROUTE_DOMAIN_GBLVAR"

     Debug Logging
    if {$static::MY_RD_FQDN_DEBUG_GBLVAR==2}{log local0. "The resolved IP for FQDN $static::MY_RD_FQDN_GBLVAR is $FQDN_IP_LCLVAR"}

     Perform some rudimentary error checking
    if { $FQDN_IP_LCLVAR ne "" } {

         Use the FQDN IP as the node if there is one
        node $FQDN_IP_LCLVAR

         Debug Logging 
        if {$static::MY_RD_FQDN_DEBUG_GBLVAR==2}{log local0. "The connection for [IP::client_addr]:[TCP::client_port] was sent to $FQDN_IP_LCLVAR"}

    } else {

         If there is no FQDN IP then drop the connection
        drop

         Debug Logging         
        if {$static::MY_RD_FQDN_DEBUG_GBLVAR>0}{log local0. "No IP was resolved."}
    }

}

Lee_Sutcliffe · ‎07-Feb-2018

Having had to deal with this recently, I've added a Code Snippet that addresses this issue but also adds redundancy to the DNS queries, validation of answers and caching.

https://community.f5.com/t5/codeshare/dynamic-fqdn-node-dns-resolution-based-on-uri-with-route-domai...