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Mr__T's avatar
Mr__T
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Feb 23, 2023

Irule Vs rewrite - FQDN hostname

Hi All, New to IRules, and rewrites.  Clients will type appname.domain.com, I need to redirect to another URL (working via IRule) that the server understands but keep the friendly name appname.doma...
application delivery
Paulius's avatar
Paulius
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Mr__T So a few things stand out to me. First is that you don't want a redirect you would like a rewrite but in your rewrite it looks like you want to add on a port at the end of the host which shouldn't be necessary because your pool member should be listening on that port already. The last is whenever they hit just "/" as the URI do you want to redirect them to a specific path? So as an example of how I believe this works.

User requests https://appname.domain.com/
F5 responds with a redirect to https://appname.domain.com/something/something/something/etc/etc/etc.html
User now requests https://appname.domain.com/something/something/something/something/etc/etc/etc.html
F5 rewrites appname.domain.com to longappname.com
F5 sends request to server on https://longappname.com/something/something/something/etc/etc/etc.html
Response comes back from server and F5 rewrites longappname.com to appname.domain.com
F5 sends response back to client for https://appname.domain.com/something/something/something/etc/etc/etc.html

If for some reason I did not understand this correctly can you provide additional information as to how it has to function?

  • Paulius's avatar
    Paulius
    Icon for MVP rankMVP
    Mar 13, 2023

    Mr__T If your pools have multiple pool members I do not believe this will be possible because you will require mapping a single FQDN to multiple server names depending on the pool member that you are sent to. Your best bet here would be to work with the server/app admins to see if they have a way of changing what they expect for the host and path. Typically all of this can be done at the server level instead of performing a bandaid at the F5 which in some cases such as yours will not work because of the single FQDN to many names issue.

    • Mr__T's avatar
      Mr__T
      Icon for Cirrus rankCirrus
      Mar 13, 2023

      Only 1 server in the pool. We tried to get the app owners to correct this at the application but they could not.

      So the server is expecting https//:servername:8443/etc/ etc/etc/landingpage. Cosmetically, the app owner does not want to see unfriendly name. 

       

      • Paulius's avatar
        Paulius
        Icon for MVP rankMVP
        Mar 14, 2023

        Mr__T The following is the base iRule and you can continue to add on additional "elseif" to this to account for additional applications and change the port "8080" to the respective port.

        when HTTP_REQUEST priority 500 {

    if {[string tolower [HTTP::host]] == "example.com"} {
        HTTP::host [string map {"example.com" "servername.example.com:8080"}[HTTP::host]]
    }

}