Execute iCall from iRule

I have an iRule that executes a sideband connection in order to execute a bash script that runs a bunch of openssl commands. I would like to implement this using iCall so that I can eliminate the sideband connection and make the script part of the big-ip configuration.

The script and handler are pretty straight forward (thanks to the DevCentral community):

 

sys icall script helloworld_script {
    app-service none
    definition {
        set ifilename [exec bash -c "ls /config/filestore/files_d/Common_d/ifile_d/*testscript.sh*"]
        exec /bin/bash $ifilename
    }
    description none
    events none
}

sys icall handler triggered helloworld_trigger {
    script helloworld_script
    subscriptions {
        helloworld_subscription {
            event-name helloworld_event
        }
    }
}

 

I can test this with:

 

generate sys icall event helloworld_event context none

 

The part I am not sure about is executing this from an iRule. The only thing I have come across is to Jason’s article which talks about using an ISTATS::set trigger from the iRule. Is this really the only way to execute an iCall from an iRule?

Thanks,

David