Nimbostratus
We are trying to loadbalance thru our LTM's using names instead of IP's. We contacted F5 support and they said there might be way using an iRule. Essentially, we are trying to loadbalance to an external site which changes IP's often and everytime they make a change it breaks our product. I should also mention we are using the proxypass irule to do header rewriting, not sure if it matters. Please help! Thx...
There was a thread about this awhile back - take a look at the discussion here for some ideas:
http://devcentral.f5.com/default.aspx?tabid=53&view=topic&forumid=5&postid=6546
(corrected the link)
JQ
Nimbostratus
Mon Dec 1 11:22:16 PST 2008 tmm tmm[10220] 01220001 TCL error: ExampleDNS CLIENT_ACCEPTED - cant read ::server_ip: no such variable while executing node $::server_ip [TCP::local_port]
iRule:
when RULE_INIT {
set ::hostname "example.com"
set ::max 10
set ::count 0
}
when CLIENT_ACCEPTED {
node $::server_ip 80
incr ::count
if { $::count == $::max } {
set ::count 0
NAME::lookup $::hostname
}
}
when NAME_RESOLVED {
log local0. "NAME_RESOLVED: [NAME::response]"
set ::server_ip [NAME::response]
}
Cirrostratus
when RULE_INIT {
Hostname to resolve address for
set ::hostname "example.com"
Resolve the hostname every X connections
set ::max 10
Force a lookup on the first connection
set ::count 10
}
when CLIENT_ACCEPTED {
Increment the global count of TCP connections
incr ::count
If we're over the limit, try to resolve the hostname
if { $::count > $::max } {
NAME::lookup $::hostname
} else {
Under the max, so use the saved IP address for this connection
node $::server_ip 80
}
}
when NAME_RESOLVED {
set answer [NAME::response]
log local0. "Received answer for $::hostname: $answer"
Check if response is an IP address
if {[IP::addr $answer mask 255.255.255.255]}{
Save the most recent answer for the hostname
set ::server_ip $answer
Reset the count as we've successfully resolved the name
set ::count 0
Specify the updated IP address for this connection
node $::server_ip 80
Current answer wasn't an IP address, so check if there is a previous valid IP
} elseif {[info exists ::server_ip] and [IP::addr $::server_ip mask 255.255.255.255]}{
Specify the updated IP address for this connection
node $::server_ip 80
No valid IP address to use, so take some default action?
} else {
log local0. "[IP::client_addr]:[TCP::client_port]: Error: No valid IP address for $::hostname"
}
}
Aaron