HTTP Payload logging breaks HTTP Keep-Alive

Afternoon all,

I've written an iRule to record the request/response payload on a REST HTTP API.

    when CLIENT_ACCEPTED {

            if { $static::PayloadLoggerDebug or $f5_connection_debug } { log local0.debug "Processing CLIENT_ACCEPTED." }

             Set the payload logging flag
            set log_payload 1
    }

    when HTTP_REQUEST priority 800 { 
            if { $static::PayloadLoggerDebug or $f5_connection_debug } { log local0.debug "$log_prefix: Processing HTTP_REQUEST at priority 800..." }

             Skip logging if no members available
            if {$splunk_bypass}{
                    if { $static::PayloadLoggerDebug or $f5_connection_debug } { log local0.debug "$log_prefix: Splunk HSL pool is down. Bypassing logging..." }
                    return
            }

             Don't allow data to be chunked
            if { [HTTP::version] eq "1.1" } {
                    if { [HTTP::header is_keepalive] } {
                            HTTP::header replace "Connection" "Keep-Alive"
                    }
                    if { $static::PayloadLoggerDebug or $f5_connection_debug } { log local0.debug "$log_prefix: Switching to HTTP Version 1.0." }
                    HTTP::version "1.0"
            }

             Split out request headers and munge into string
            set headers [HTTP::header names]
            if { $static::PayloadLoggerDebug or $f5_connection_debug } { log local0.debug "$log_prefix: Request HTTP Headers = $headers" }
            set request_headers "'"
            foreach header $headers {
                    set value [HTTP::header value $header]
                    if { $static::PayloadLoggerDebug or $f5_connection_debug } { log local0.debug "$log_prefix: Request HTTP Header $header value = $value" }
                    append request_headers "$header=$value "
            }
            set request_headers [string trimright $request_headers " "]
            append request_headers "'"
    }

    when HTTP_REQUEST_DATA {
            if { $static::PayloadLoggerDebug or $f5_connection_debug }{ log local0.debug "$log_prefix: Collected [HTTP::payload length] bytes."}
            set request_payload [HTTP::payload]
    }

    when HTTP_RESPONSE priority 50 {
            if { $static::PayloadLoggerDebug or $f5_connection_debug } { log local0.debug "$log_prefix: Processing HTTP_RESPONSE at priority 50..." }

             Skip logging if no members available
            if {$splunk_bypass}{
                    if { $static::PayloadLoggerDebug or $f5_connection_debug } { log local0.debug "$log_prefix: Splunk HSL pool is down. Bypassing logging..." }
                    return
            }

             Split out the response headers and munge into string
            set headers [HTTP::header names]
            if { $static::PayloadLoggerDebug or $f5_connection_debug } { log local0.debug "$log_prefix: Response HTTP Headers = $headers" }
            set response_headers "'"
            foreach header $headers {
                    set value [HTTP::header value $header]
                    if { $static::PayloadLoggerDebug or $f5_connection_debug } { log local0.debug "$log_prefix: Response HTTP Header $header value = $value" }
                    append response_headers "$header=$value "
            }
            set response_headers [string trimright $response_headers " "]
            append response_headers "'"

             Collect the response
            if { $response_length > 0 } {
                    if { $static::PayloadLoggerDebug or $f5_connection_debug } { log local0.debug "$log_prefix: Collecting $response_length bytes from response." }
                    HTTP::collect $response_length
            }

             Calculate actual content-length
            set response_length_real [HTTP::payload length]
            if { $static::PayloadLoggerDebug or $f5_connection_debug } { log local0.debug "$log_prefix: Real response content-length = $response_length_real." }

             Correct the response_length to correct value if required. 
            if { $response_length != $response_length_real } {
                    if { $static::PayloadLoggerDebug or $f5_connection_debug } { log local0.debug "$log_prefix: Updated \$response_length value." }
                    set response_length $response_length_real
                    if { $static::PayloadLoggerDebug or $f5_connection_debug } { log local0.debug "$log_prefix: New \$response_length value is $response_length." }
            }
    }

    when HTTP_RESPONSE_DATA {
            if { $static::PayloadLoggerDebug or $f5_connection_debug } { log local0.debug "$log_prefix: Processing HTTP_RESPONSE_DATA." }

             Gather response data
            set response_payload "[HTTP::payload]"
    }

A lot of the above feeds into a larger iRule framework. E.g. we use a SplunkHTTPS iRule to actually do the HSL logging out to a syslog server. The 'HTTP::collect' is also called from that iRule aswell.

However when testing this iRule, I've identified an issue whereby it appears to be breaking HTTP Keep-alive connections to some of our GF3 application servers.

Removing this rule restores the keep-alive functionality.

Any pointers on how I can maintain the keep-alive functionality and also be able to log the request/response data?

Cheers Gavin