Rewrite URL based on selected node for load-balancing

when HTTP_REQUEST_SEND {
set nodenum [class match -value [LB::server addr] equals lb_server_datagroup]
log local0. $nodenum
}

when HTTP_REQUEST_SEND {

 Need to force the host header replacement and HTTP:: commands into the clientside context
 as the HTTP_REQUEST_SEND event is in the serverside context
clientside {

switch -glob [LB::server addr] {

"1.1.1.1" {
HTTP::header replace Host "newHostHeader01"
}

"1.1.1.2" {
HTTP::header replace Host "newHostHeader02"
}

etc...

}

}

}
 

Thanks Kevin ;) I'll let you the result once implemented (I'm not in the lab now) if you're interested.

Hi,

when RULE_INIT 
 Log debug messages to /var/log/ltm? 1=yes, 0=no 
set static::rewrite_debug 1 
 External hostname for the web application 
set static::external "newHost.com" 
} 

when HTTP_REQUEST_SEND { 
 Need to force the host header replacement and HTTP:: commands into the clientside context 
 as the HTTP_REQUEST_SEND event is in the serverside context 
clientside { 
 Different action depending on the node selected for load-balancing 
switch [LB::server addr] { 
"1.1.1.1" { 
HTTP::header replace Host "MyHost01" 
if {$static::rewrite_debug}{log local0. "[IP::client_addr]:[TCP::client_port]: HTTP Host header rewritten with MyHost01"} } 
"1.1.1.2" { 
HTTP::header replace Host "MyHost02" 
if {$static::rewrite_debug}{log local0. "[IP::client_addr]:[TCP::client_port]: HTTP Host header rewritten with MyHost02"} } 
} 
} 
} 

when HTTP_RESPONSE { 
 Replace all internal Host headers with $static::external value defined in RULE_INIT section 
HTTP::header replace Host $static::external 
if {$static::rewrite_debug}{log local0. "[IP::client_addr]:[TCP::client_port]: HTTP Host header rewritten with -> $static::external"} 
if { [HTTP::is_redirect] } { 
HTTP::header replace Location [string map -nocase "MyHost01.domainname.com newHost.com" [HTTP::header value Location]] 
HTTP::header replace Location [string map -nocase "MyHost02.domainname.com newHost.com" [HTTP::header value Location]] 
etc... --> Here I'm looking for a regex to replace the Location header in a single line while concatening the rest of Location value (i.e. with the part after https://domain_name/)
} 
}

In a nutshell, now it only remains after [HTTP::is_redirect] to replace the domain name into the Location header in a single line thanks to a regex. For me more easy to say than to do 🙂 That's why I'm still here, asking for your valuable help guys (and girls).

Like this, I won't need to have as much lines as there are backend servers. Once done, we'll can consider this iRule as complete.

I hope I've been clear enough 🙂

when HTTP_RESPONSE {
if { [HTTP::is_redirect] } {
set host_new "newHost.com"
set uri_old [string tolower [HTTP::header Location]]
if { [scan $uri_old {%*[http://|https://]%[^/]} host_old] } {
set map_exp "set uri_new \[string map {$host_old $host_new} $uri_old\]"
eval $map_exp
HTTP::header replace Location $uri_new
}
}
}

just another example.

original response

[root@ve11a:Active:Changes Pending] config curl -I http://200.200.200.101/something

[root@ve11a:Active:Changes Pending] config curl -I http://200.200.200.111/something

response after passing bigip

[root@ve11a:Active:Changes Pending] config curl -I http://172.28.20.111/something