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junland_314810's avatar
junland_314810
Icon for Nimbostratus rankNimbostratus
Nov 16, 2017

Port Redirection Failure

I'm using a Non-Prod F5 running 12.1.2 Build 1.292.271.

We have a cluster of nodes that serve up various Apps on different ports.

/App1 - 80

/App2 - 81

/App3 - 82

I have configured a pool with members that have all service ports enabled. Also a single VS with a VIP and a service port of 0.

Here is my iRule:

when HTTP_REQUEST {
    switch -glob [HTTP::uri] {
        "/App1*" {
            set port 80
        }
        "/App2*" {
            set port 81
        }
        "/App3* {
            set port 82
        }
    }
}

when LB_SELECTED {
      pool [LB::server pool] member [LB::server addr] $port
}

When running statistics on the iRule I get failures in the "LB_SELECTED" part however from my prospective this should be the correct syntax to change the service port on a pool. I would like some feedback on this configuration and if someone can comment on this configuration. Thanks.

apps
big ip
devops
docker
irule
iRules
lb_selected
LTM

1 Reply

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  • Lee_Sutcliffe's avatar
    Lee_Sutcliffe
    Icon for Nacreous rankNacreous
    Nov 16, 2017

    You can't use the 

    pool
    command in LB_SELECTED as the load balancing decision has already been made. Try placing your pool command in HTTP_REQUEST

    (you also had a missing end quote in the switch)

    https://devcentral.f5.com/wiki/iRules.pool.ashx

    when HTTP_REQUEST {
    switch -glob [HTTP::uri] {
        "/App1*" {
            set port 80
        }
        "/App2*" {
            set port 81
        }
        "/App3*" {
            set port 82
        }
    }

    if {([info exists port]) && ($port ne "")}  {
        pool [LB::server pool] member [LB::server addr] $port
    }
}

    PS - Pool command added inside an 

    if
    , this is because the $port variable may not exist if a connection arrives with a different URI to the one in the switch statement. If this happens you'll get a TCL error.