Does http::payload replace work on the http request?

i dont believe so, there is not actual http payload in a http request, just the request and the headers i believe. so there is no need to change something here right?

do you have a specific situation you want to tackle?

HTTP POSTs contain HTTP payloads, although in most use cases it's the HTTP headers that most customers want replaced.

You can replace ANY HTTP request payload in the same manner as response payload.

HTTP::payload replace 0 [HTTP::header Content-Length] "blah-blah-blah"

As Kevin said, this certainly is possible: Here's an example from the HTTP::collect wiki page. You can also check the HTTP::payload wiki page for more info on doing the payload replacement: https://devcentral.f5.com/wiki/iRules.http__collect.ashx https://devcentral.f5.com/wiki/iRules.http__payload.ashx

From https://devcentral.f5.com/wiki/iRules.http__collect.ashx
 Collect a request payload
when HTTP_REQUEST {

  if {[HTTP::method] eq "POST"}{
     Trigger collection for up to 1MB of data
    if {[HTTP::header "Content-Length"] ne "" && [HTTP::header "Content-Length"] <= 1048576}{
      set content_length [HTTP::header "Content-Length"]
    } else {
        set content_length 1048576
    }
     Check if $content_length is not set to 0
    if { $content_length > 0} {
      HTTP::collect $content_length
    }
  }
}
when HTTP_REQUEST_DATA {
   do stuff with the payload
  set payload [HTTP::payload]
}

This is great. Thank you.