Irule to extract the host name and it in a file

You can create log messages that are logged to /var/log/ltm

when HTTP_REQUEST {
    log local. "HTTP request received from Host: [HTTP::host]"
}

Logging to other files/locations could be a risk as it may not be included in a log rotation therefore could potential fill your disk up quite quickly.

Hi,

you can do it with

when HTTP_REQUEST {
    log local0. "Request from : [IP::remote_addr] / Host requested [HTTP::host]"
}