Forum Discussion

craddockchris's avatar
craddockchris
Icon for Altostratus rankAltostratus
Apr 22, 2024

iRule assistance

Dear community,

Could someone provide me with an example of an iRule that does the following:

 

I would like to have a single inbound VIP for API calls. These calls could go to one of 2 Pools depending on what is in the URI. How can I write an iRule that looks for a certain string in the URI and send the request to one pool or the other depending on what is in the URI?

 

Thank you. 

devops
  • candc's avatar
    candc
    Icon for Cirrus rankCirrus
    Apr 22, 2024

    At its simplest...

    when HTTP_REQUEST {
    switch -glob -- [string tolower [HTTP::uri]] {
        "/thing-a/*" { pool "apiPoolA" }
        "/thing-b/*" { pool "apiPoolB" }
        default { HTTP::respond 400 content "Unsupported URI" noserver }
    }
}

    i.e., in the HTTP_REQUEST event, read the URI, convert it to lower-case (for easier comparing) and compare it to one or more simple patterns. 

    If the URI starts with /thing-a/, forward to one specific backend pool; if it starts with /thing-b/, forward to another.

    If the URI does not match either of those patterns, respond with a basic HTTP error message.

    Note that, to the BIGIP, the term "URI" means "the path and querystring".  If you actually want just the path, try [HTTP::path]; if you want the hostname, try [HTTP::host]; or if you want both, consider "[HTTP::host][HTTP::uri]".

    If you need the scheme (i.e. if it is HTTP or HTTPS), it can be a little trickier.  Possibly [expr { [PROFILE::exists clientssl] ? "https" : "http" }].